THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE …EFFECT OF POLYMER COATED UREA ON GROWTH AND YIELD...

EFFECT OF POLYMER COATED UREA ON

GROWTH AND YIELD OF RICE (Oryza sativa L.)

THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS

FOR THE DEGREE OF

Master of Science (Agriculture)

in

Agronomy

DEPARTMENT OF AGRONOMY

INSTITUTE OF AGRICULTURAL SCIENCES BANARAS HINDU UNIVERSITY

VARANASI - 221 005

I D. No. : A-13006 2015 Enrolment No. : 359617

Supervisor

Prof. Avijit Sen Submitted by

Rajani Sirvi

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M.Sc.

Pravin K

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2012

Dr. Avijit Sen Professor & Head Phone: 05426702415

Email: [email protected]

Department of Agronomy

Institute of Agricultural Sciences

Banaras Hindu University

Varanasi-221005

U.P. (INDIA)

Ref. No. ……………… Date: ..............

CERTIFICATE

To,

The Registrar (Academic)

Banaras Hindu University,

Varanasi- 221005 (India).

Through: The Head

Department of Agronomy

Institute of Agricultural Sciences

Banaras Hindu University,

Varanasi- 221005.

Dear Sir,

I have great pleasure in forwarding the thesis entitled “Effect of polymer coated

urea on growth and yield of rice (Oryza sativa L.).”submitted by Ms. Rajani Sirvi

(I.D. No. A-13006) in partial fulfilment of the requirements for the degree of MASTER

OF SCIENCE (Agriculture) in AGRONOMY, Institute of Agricultural Sciences,

Banaras Hindu University, Varanasi (U.P.) and placing on record that he has completed

the requisite residential requirements as contained in the statutes of the University.

I certify that the work has been carried out under my guidance and the data

forming the basis of this thesis, to the best of my knowledge are original and genuine and

no part of the work has been submitted for any other degree or dissertation.

Thanking you,

FORWARDED BY, Yours faithfully,

(Avijit Sen) Supervisor

EFFECT OF POLYMER COATED UREA ON GROWTH

AND YIELD OF RICE [Oryza sativa (L.)]

by

Rajani Sirvi

Thesis Submitted in Partial Fulfilment of the Requirements for the Degree of

Master Of Science (Agriculture)

In

Agronomy

DEPARTMENT OF AGRONOMY

INSTITUTE OF AGRICULTURAL SCIENCES

BANARAS HINDU UNIVERSITY

VARANASI – 221005

2015

I.D. No.A-13006 Enrolment No.359617

APPROVED BY ADVISORY COMMITTEE

CHAIRMAN Dr. Avijit Sen Professor

Department of Agronomy, I.Ag.Sc., BHU.

MEMBERS Dr. Yashwant Singh Professor

Department of Agronomy, I.Ag.Sc., BHU.

Dr. Praveen Prakash

Associate Professor

Department of Plant Physiology,I.Ag.Sc., BHU.

EXTERNAL EXAMINER

Acknowledgement

I bow my head and offer flowers of reverence to Mahamana Pt. Madan Mohan Malviya, the Founder of Banaras Hindu University, for his life time sacrifice and efforts in establishing such a great temple of learning for the cause of millions of students like me.

It is exquisitely a jubilating occasion and unique opportunity to express my hearty indebtedness to my esteemed guide Prof. Avijit Sen, Head of Department, Department of Agronomy, Institute of Agricultural Sciences, Banaras Hindu University, Varanasi. I feel extreme pleasure to owe my profound sense of gratitude and indebtedness for his scholastic guidance, perceptive criticism, affection and constant source of inspiration which enabled me to complete the task with great ease and will thus continue to occupy a prominent place in my memory.

I owe my sincere thanks to the members of my advisory committee, Prof. Yashwant Singh, Department of Agronomy and Dr. Praveen Prakash, Department of Plant Physiology, Institute of Agricultural Sciences, Banaras Hindu University, Varanasi (U.P.) for their critical suggestion, impeccable and benevolent guidance.

I am grateful to Dr. Praveen Prakash Department of Plant Physiology, Institute of Agricultural Sciences, Banaras Hindu University, Varanasi (U.P.) for extending all possible help in his laboratory during the course of this study.

I am highly obliged to Prof. Rajendra Prasad Singh, Former Head, Department of Agronomy for providing the necessary research and academic facilities during the course of investigation.

My special thanks to Mr. Nandu Ram Yadav, Mr. Vijay Pratap Singh, Mr. J.C.N.Tripathi and Mr. Shayam Sundar for whole hearted co-operation and continues inspiration.

With profound regards in a more personal sense, I owe deepest debts to my parents Shri Narayan Lal and Smt. Hastu Devi who taught me the value of wisdom based on erudition but without enslaved by it and their persistent inspiration, selfless sacrifice, continuous encouragement and blessing gave untiring help and have enabled me to be so today.

I am quite unable to find appropriate words as to express my deepest sense of gratitude to my beloved, my best friend Dharm Singh Meena, my beloved sister Rekha Sirvi, my brothers Mr. Ranveer Sirvi, Mr. Dinesh Sirvi and Mr. Shankar Lal Sirvi. It was their zeal and enthusiasm which made it possible for me to complete my logical end of this study. My words are too feeble to give my inner feelings. Their constant encouragement, moral and emotional support rendered throughout my education for which I will remain indebted to them throughout my life.

Without the help of seniors no one can learn the lesson of life and cannot teach the same to loving juniors so, heartfelt and special thanks to my seniors. Mr. Praveen Upadhyay , Mr. Anandi Lal Jat, Mr. Shyoji Lal Bairwa, Mr. Pradeep Singh, Mr. Santosh Kumar, Mr. Kanhaiya Lal Regar, Mr. Santosh Meena, Mr. Surya Pratap Singh, Miss Ekta Kumari, Miss Mona Nagargade, Mr. Visal Tyagi, Mr. Gorav and Rupesh Kumar Meena for their co-operation during the study and investigation.

The words are inadequate to express my feelings to my friends Kiran Hingonia, Mishan Das, Surajyoti Pradhan, Aurdit Sankar, Geetangali Singh, Ram Singh, Sandeep Sihag, Shivam Shukla, Shiv Bahadur, Lala Ram, Rajendra Prashad Meena, Gangadhar Nanda, Dharmendra Kumar and Chandra Shekar for their moral support, co-operation, priceless suggestions and their immense love and affection which always animated me to face the challenges and material support during the thesis work.

It is pleasure for me to give thanks to my lovely juniors Deshraj, Pooja Kumari, Twinkle, Swati and Dinesh Sirvi.

Before pen down, I once again confess that I do not know how to acknowledge the help and co-operation of my supervisor, members of advisory committee, family members and relatives, seniors, juniors, colleagues but above feeling are followed from the core of my heart in the shape of words and as gospel truth.

The graces of the God are always blessed to me and give me patience and power to overcome the difficulties which came my way in accomplishment of this endeavour. I cannot dare to say thanks but only pray to bless me always.

Above all, my humble and whole hearted prostration to Lord Baba Vishwanath, Sankat Mochan & Goddess Saraswati for their blessings.

Lastly, I bow at the feet of “Goddes Sarswati” with whose omnipresent blessing today on the eve of completion of my thesis. This is a long adventurous journey to the unknown destination with a hope for future. I was not alone in this journey to accomplish this Herculean task, and I am in a position to acknowledge all those, who helped me a lot to cross the way in finishing the marathon work.

Date: (Rajani Sirvi) Place: Varanasi Department of Agronomy

Institute of Agricultural Sciences, Banaras Hindu University, Varanasi-221005

CONTENTS

S. No. Chapters Page No.

1. Introduction 1-4

2. Review of Literature 5-21

3. Materials and Methods 22-37

4. Experimental Findings 38-46

5. Discussion 47-53

6. Summary and Conclusion 54-55

Bibliography i-vii

../../../../Users/ACER/AppData/Roaming/Microsoft/Word/Front.doc

LIST OF TABLES

Table No. Particular Page No.

Table 3.1 Weekly meteorological data of Varanasi during experiment

period (June, 2014 to October, 2014) .................................................. 23

Table 3.2 Physico-chemical and mechanical analysis of experimental soil ........ 26

Table 3.3a Treatment details ................................................................................. 27

Table 3.3a Detail of layout .................................................................................... 27

Table 3.4 Schedule of field operations carried out during experiment ............... 31

Table 3.5 Method of chemical analysis of plant samples………………....…….36

After

Page No.

Table 4.1 Effect of different treatments on nitrogen content in soil at 3 days

intervals ………......................................................................……. 38

Table 4.2 Effect of different treatments on plant height...................................... 39

Table 4.3 Effect of different treatments on number of tillers .............................. 39

Table 4.4 Effect of coated urea on number of leaves ……………………......…40

Table 4.5 Effect of different treatments on chlorophyll content (SPAD) ...… 40

Table 4.6 Effect of different treatments on fresh and dry weight per hill at

harvest.……….......................................................................… 41

Table 4.7 Effect of different treatments on length and weight of panicle,

number of grain per panicle and test weight ................................... 43

Table 4.8 Effect of different treatment on grain, straw, total biological yield

and harvest index..............................................................................44

Table 4.9 Effect of coated urea on nitrogen, phosphorus and potassium

content in grain..................................................................................45

Table 4.10 Effect of coated urea on nitrogen, phosphorus and potassium

content in straw ................................................................................45

Table 4.11 Effect of different treatment on nutrient uptake by hill ....................... 46

Table 4.12 Effect of coated urea on protein content in grain ................................ 46

LIST OF FIGURES

Figure No. Particular After

Page No.

Fig. 3.1 Meteorological observations (Standard week wise) obtained

from the Meteorological observatory of the Banaras Hindu

University, during experimental period (2014) .................................. 24

Fig. 3.2 Layout of experimental field ............................................................... 27

Fig. 4.1 Effect of different treatments on nitrogen content in soil at 3

days intervals ....................................................................................... 38

Fig. 4.2 Effect of different treatments on plant height .................................... 39

Fig. 4.3 Effect of different treatments on number of tillers ............................ 39

Fig. 4.4 Effect of different treatments on chlorophyll content (SPAD) .......... 40

Fig. 4.5 Effect of different treatment on grain, straw, total biological

yield ..................................................................................................... 44

LIST OF PLATES

Plate No. Particular After

Page No.

Plate no. 1 Xanthium strumarium .......................................................................... 28

Plate no. 2 Soxhlet extraction unit ......................................................................... 32

Plate no. 3 Rotary evaporator ................................................................................ 32

Plate no. 4 Xanthium strumarium extract ready for use as herbicide .................... 45

Plate no. 5 Xanthium strumarium extract applied in field ..................................... 45

Abbreviations and Symbols Used

% Per cent

/ Per

@ At the rate

C.D. Critical difference

cm Centimeter

SEm± Standard error of mean

d.f. Degree of freedom

DAT Days after transplanting

dSm-1 Decisiemen per meter

e.g. For example

EC Electrical conductivity

et al. And others

Fig. Figure

ac acre

g Gram

ha Hectare oC Degree centigrade

hrs Hours

i.e. Id est (that is)

K Potassium

N Nitrogen

P2O5 Phosphorus

kg Kilogram

lb pound

m Meter

Max. Maximum

Min. Minimum

mm Millimeter

mt Million tones

N Nitrogen

No. Number

NS Non significant

pH Puissance de hydrogen

q Quintal

t Tonnes

viz. Namely

Chapter I

INTRODUCTION

Rice (Oryza sativa L.) is one of the major staple food crops for more than half

of the world population and is grown worldwide. It is a nutritious cereal crop which

provides 20 % of the calories and 15 % of protein consumed by world’s population,

besides minerals and fiber. The slogan ‘Rice is Life’ is most appropriate for India as

this crop plays a vital role in our national food security and a means of livelihood for

millions of rural household. In India, this crop is grown in 43.9 million hectare of land

with total annual production of 106.5 million tonnes with an average productivity of

24.24 q ha-1 (Anonymous, 2014).

Rice is most widely consumed in one or other form by poorest to richest

person in this world. However, rice is a poor source of essential micronutrients such

as Iron (Fe) and Zinc (Zn). The average content of protein in rice grains is 8 per cent,

iron 1.2 mg/100 g and zinc 0.5 mg/100 g.

To keep pace with demands of increasing populations, global rice production

needs to be increased significantly in the next 10 years. Rice production has to be

raised up to 160 million tonnes by 2030 with a minimum annual growth rate of 2.35

per cent to meet the increasing food demand. The possibility of expanding the area

under rice is limited. Therefore, this extra rice production needed has to come from a

productivity gain. The major challenge to achieve this gain lies with weed, labour and

chemical management of which will ensure long-term sustainability. Rice is mostly

grown in lowland area under wet condition usually associated with leaching, run-off,

volatilization and denitrification losses of most of applied nitrogen as fertilizer.

Nitrogen (N) plays a central role in modern agriculture. It is an essential

nutrient and also the major limiting factor in most agricultural soils under all agro-

ecological condition. Poor nutrient utilization and nitrogen losses from urea

applications have been reported for many years (Khalil et al., 2009). The N losses

from applied urea have been estimated to be 30 to 60 per cent in tropical soil (Freney

et al., 1981). Low recovery of N in annual crop is associated with its loss by

Introduction

~2~

volatilization, leaching, surface runoff, and denitrification. However, worldwide

recovery of N in cereal crops is usually 30-50 per cent (Ladha et al., 2005).

Rice utilizes conventionally broadcast nitrogenous fertilizers very

inefficiently. Mitsui (1954) estimated that rice commonly recovered only 30-40 per

cent of applied N, whereas upland crops recover 50-60 per cent. The other 60-70 per

cent of the N applied to rice is subject to gaseous losses through nitrification-

denitrification and ammonia volatilization, or to losses in water through leaching and

runoff (Broadbent 1978, 1979; Craswell and Vlek 1979). Bilal et al. (1979) and Lin

et al. (1975) reported field leaching losses of 4-30 per cent from ammonium sulfate;

whereas Rao (1977) reported 17 per cent loss from urea and up to 63 per cent losses

from added ammonium nitrogen (through denitrification) as measured from soils

undergoing short but frequent cycles of wetting and drying (Reddy and Patrick, 1975).

Nitrogen use efficiency of rice can be increased by reducing the solubility of

nitrogenous compound through physical or chemical methods. Physical methods

depend on coating or encapsulation of water soluble materials with outer layers of

organic or inorganic materials. Encapsulated materials are characterized by diffusion

controlled release of nutrients through the surface layer. Physical methods of control

include sulphur, polymer and mixed. sulphur- polymer encapsulated materials

(Oertli,1980; Booze-Daniels and Schmidt, 1997) and resin coatings (thermoset and

thermoplastic resins) such as osmocote (Hulme and Buchheit, 2007).

Chemical methods of control include conversion of nitrogen to polymeric

forms that have reduced water solubility like urea formaldehydes, isobutylidene

diurea (IBDU) and crotonylidene diurea (CDU). Other types of slow release and

controlled release formulations include gel forming materials, zeolite based materials

as also urease and nitrification inhibitors.

Controlled release fertilizer (CRF) is a purposely designed manure that

releases active fertilizing nutrients in a controlled, delayed manner in synchrony with

the sequential needs of plants for nutrients, by virtue of which it enhances nutrient use

efficiency along with more yields (Shaviv, 2005). An ideal controlled release fertilizer

is coated with a natural or semi-natural, environmental friendly macromolecule

Introduction

~3~

material that retards fertilizer releases to such a slow pace that a single application to

the soil can meet nutrient requirements for model crop growth.

Sulfur has been used to produce controlled release coated urea (CRCU) for

decades. Sulfur-coated urea, or SCU, fertilizers release nitrogen via water penetration

through cracks and micropores in the coating. Once water penetrates through the

coating, nitrogen release is rapid. Sulfur-coated products typically range from 32 to 41

per cent elemental nitrogen by weight. The sulfur coating process was originally

developed by the Tennessee Valley Authority.

A technique for coating urea with neem cake was developed at IARI, New

Delhi. The neem cake is coated on urea using a coal-tar kerosene mixture (Prasad

et al., 1999). Another technique of coating urea with neem oil micro-emulsion was

developed at IARI (Suri et al., 2000). Trials conducted by KRIBHCO showed that

neem emulsion coating was superior to prilled urea, extended the shelf life of urea,

helped in sustaining nitrogen in the soil for a very long time resulting in better yields

(Prasad et al., 2005, 2007).

Polymer coated urea is one such type of controlled release fertilizer, which

potentially keeps more N in the root zone, reduces N losses, improves nitrogen use

efficiency and reduces negative effect on the environment. The most promising for

widespread agricultural use are polymer coated urea which can be designed to release

nutrient in a controlled manner (Baligar, 2015).

Polyolefin-coated fertilizer (POCF) is one of the CRFs developed in Japan that

shows highly controlled nutrient-release characterized by temperature. This accurate

nutrient control enables large amount of PCU to be placed with seeds or seedlings

without salt damage (Kaneta et al., 2010).

A limited number of studies comparing polymer-coated urea with urea have

indicated crop yield can be higher, lower or unchanged depending on the crop and

environmental conditions during the growing season (Golden et al., 2009; Noelisch

et al., 2009; Blackshaw et al., 2011). Noellsch et al., (2009) studied the effects of

conventional and slow-release N fertilizer sources and landscape position on corn

(Zea mays L.) in a claypan soil. Anhydrous ammonia and PCU increased grain yield

http://en.wikipedia.org/wiki/Micropore

http://en.wikipedia.org/wiki/Tennessee_Valley_Authority

Introduction

~4~

by 1470 to 1810 kg ha-1 over urea. Based on the grain yield and different fertilizer

cost and crop prices, gross profit differences for use of PCU and preplant-applied

anhydrous ammonia compared with urea in the low-lying position could range from

$50 to $642 ha-1.

Controlled release fertilizers not only increase the nutrient use efficiency but

also reduce cost of production and pollution hazards. The accurate nutrient control

enables large amount of PCU to be placed with seeds or seedlings without salt

damage (Kaneta et al., 2010). Hence present investigation entitled “Effect of polymer

coated urea on the growth and yield of rice [Oryza sativa (L.)]” was carried out

during Kharif season of 2014 at the Agricultural Research Farm of the Institute of

Agricultural Sciences, Banaras Hindu University, Varanasi, Uttar Pradesh the with

following specific objectives.

1. To find out nitrogen content in soil with deep placement of different coated

urea fertilizers like polymer coated urea, neem coated urea, sulphur coated

urea and urea supergranule.

2. To find out their effect on growth, yield and nutrient uptake by rice.

Chapter- II

Review of Literature

Rice (Oryza sativaL.), one of the most important cereals, is the premier food

crop not only in India but in world also and is grown extensively in tropical and sub-

tropical regions of the world. Rice is mostly cultivated in lowland area under wetland

condition usually associated with leaching, run-off, volatilization and denitrification

losses of most of the applied nitrogen as fertilizer and reduces use efficiency below

30%. For rice, nitrogen accounts for approximately 19-20% of total variable

production cost (Watkins et al., 2010).

Rice being an important food crop of the world has been studied by a large

number of research workers for different inputs and agro-techniques in various parts

of India and abroad. The present field trial was designed to find out the “Effect of

polymer coated urea on the growth and yield of rice (Oryza sativa L.)”. In this

chapter an attempt has been made to critically review the research works carried out

within the country and abroad on the context stated above.

2.1 Polymer coated urea (PCU)

Nowsher et al. (1988) reported that sulphur coated urea was superior to

conventional method of urea application and point placement of urea super granules at

higher nitrogen rates. At lower nitrogen rates, there were no significant responses.

Gandeza et al. (1991) and Zvomuya et al. (2003) reported that from Agrium

PCU (polymer coated urea) N release (97%) peaked between 135 and 140 days after

planting (DAP) and reached a plateau after this point. For Kingenta PCU (polymer

coated urea), %N release was found to be a linear function of DAP, the peak per cent

N release (%NR) had not been reached by the last sampling date.

An experiment on urea release from single granule in free water at 300 C

indicated that the release rate depended on size of granule, coating thickness and

water permeability (Shaviv et al., 2003). The rate of release was inversely

proportional to r × l2 andthe lag-period is proportional to the product of granule radius


~ 6 ~

(r) and coating thickness (l) and inversely dependent on the driving force and the

water permeability.

Shaviv (2005) concluded that release rate was inversely dependant on the

product of granule radius (R0) and coating thickness (l).The release rate increased due

to a decrease in thickness (l) and radius (R0).

Kanno (2008) stated that N dissolution from polyolefin coated urea (POCU-30

and 70) was about 80% of the total N at around 40 and 90 days after sowing (DAS) in

1994, and 40 and 100 DAS in 1995, respectively . At the end of the growing season of

maize crop (112 DAS), POCU-30, POCU-70 and POCU-S60 had dissolved95, 86,

85% N in 1994 and 96, 83, 85% N in 1995, respectively. Therefore, the actual

fertilizer-N supply of the POCU-70 and POCU-30+S60 were 126-129 and 133 kg N

ha-1 respectively, and were lower than that of the urea (150 kg N ha-1).

Wilson et al. (2009) found that polymer-coated urea incubated in

polypropylene mesh pouches with 1.2 mm2 openings and 43% open area had

significantly greater N release than pouches made from weedblock material with 0.07

mm2 openings and 24% open area after 40days after planting (DAP), but initial

release rate was similar. The polypropylene mesh allowed prills to come in close to

the soil compared with weedblock bags and may explain the difference in per cent N

release (%NR).

Rosen et al. conducted an experiment in 2010 to compare differences in N

release rates and tuber yield and quality between dealer gradeEnvironmentally Smart

Nitrogen (ESN), potentially damaged ESN and stabilized N products. They observed

that N release from the airboom demaged ESN (A) was much more rapid than release

from a comparable application of dealer grade product – ESN (C). Sixty per cent of

the N had been released within 8 days after application of the air boom ESN

(ESN-A) which was 12% faster than the undamaged control ESN (ESN-C). In a

leaching year, therefore risk of losses would be minimized by using undamaged ESN.

Yi et al. (2011) found that the accumulation of NO3- -N in 0-100 cm soil layer

in all treatments ranged from 39.70-49.93 kg ha-1, and was the lowest with 39.70 kg

ha-1 in treatment PU4 (40% PCU60+60% U). The N release pattern of PCU-60 under


~ 7 ~

field condition better fitted the N absorption characteristics of winter wheat that

minimize the risk of leaching losses.

Wang et al. (2011) observed that 100% N was released in about 220 hrs from

polymer coated urea (PCU) and polymer coated-NPK (PC- NPK) at 1000C in contrast

to at 25°C where only 63.6% to 70.8% N was released over a period of 220 days. At

100°C, per cent N release from polymer coated urea (PCU) was generally greater than

that from PC-NPK at any given time throughout the incubation but at 25°C, per cent

N release was greater from PCU than that from PC-NPK during first 100 days,

subsequently, the trend was reversed till the end of 216 days incubation period.

Trinh et al. (2014) observed that the release time proportionally depends on

the particle size. Release time and rate of release increases as particle size changes

from 1 to 4 mm. Diffusive flux was 2.04×10-6 mol/(m2.s) as coating thickness was

0.050 mm after which it decreased to 0.65×10-6 mol/(m2.s) with a 0.150 mm of

coating thickness. Release time also decreases due to an increase on coating thickness.

Release time with 0.1 mm coating was 76.85 days which is comparatively lower than

0.125 mm coating thickness with release time 93.75 days. The difference between two

thicknesses was 0.025 mm but release time increased 22%.

2.2 Effect of polymer coated urea (PCU) on growth attributes

A growth-chamber study showed that barley roots proliferated around polymer

coated urea granules, resulted in greater root mass and N uptake per unit of root

compared to a conventional urea (Zhang et al., 2000a, 2000b).

Schwab and Murdock conducted an experiment in 2003-04 to study the effect

of source × rate interaction or main effect of source on dry matter, grain yield as well

as plant N uptake in corn and observed a non-significant effect at both the locations

Lexington and Princeton. However, dry matter at the V6 growth stage was recorded

higher values for the polymer coated urea as compared to the ammonium nitrate (AN)

at the Princeton location. Dry matter increased as rate of N increased at both the

locations.

http://www.tandfonline.com/doi/full/10.1080/00103621003592390#CIT0020


~ 8 ~

Singh et al. (2004) stated that maximum dry matter accumulation in paddy

(excluding 30 DAT) took place with NPK + 75% pyrite + 25% polyolefin resin

coated slow release Fe (PRCSRFe) which was statistically superior to other sources

except NPK + 50% pyrite + 50% polyolefin resin coated slow release Fe (PRCSRFe).

Pack et al. (2007) revealed that there were no significant difference in leaf,

stem, or leaf + stem dry weights for potato with any of the treatments sampled at full

flower,indicated similar potato plant sizes. Though, tuber dry weights varied at

harvesting with different treatments viz.TRT-10 (146 kg ha−1 N; 133.9 g plant−1),

TRT-6 (146 kg ha−1N; 110.4 g plant−1), and TRT-14 (146 kg ha−1 N; 108.0 g plant−1)

being significantly higher than the No-N (82.3 g plant−1) treatment.

Sahota et al. (2010) revealed that ESN resulted in significantly higher dry

matter yield of timothy than urea and the effect increased with the increasing rates of

N application, from 0 to 105 kg ha-1, more or less linearly.

A study was conducted at nine-site in Alberta,Lethbridge to compare seed-

placed environmentally smart nitrogen (ESN) with seed-placed untreated urea on

stand establishment in canola. It was found that ESN applied at 136 pounds per acre

(60 pounds of actual nitrogen) could be safely applied in the seed row without any

injury to seed, seed germination and seedling establishment.

The result of an experiment conducted in china by Jan-gang et al. (2010)

showed that in plough layer, root length density of summer maize from polymer

coated fertilizer N (PCFN) at the rate of 120 &180 kg ha-1 N with co-situs placement

was comparatively higher near stem than those from conventional fertilizer (180 kg

ha-1 N) or no fertilized treatments. Approximately 59-64% of total root was distributed

in surface layer from 0-10 cm near the stem of maize plant.

Junejo et al. (2010) recorded that the application of coated urea increased dry

matter yield by 20 to 60% pot-1as compared to urea alone. Among all the treatments,

the highest dry matter yield (29.25 g pot-1) was obtained from gelatin Cu coated urea

and (26.50 g pot-1) micronutrient coated urea treated pots in maize. The uncoated urea

produced the least dry matter yield (19 g pot-1) at the same level of N application.


~ 9 ~

Fageria (2011) revealed that root length and root dry weight were significantly

influenced by nitrogen fertilization in lowland rice. Polymer coated urea (PCU)

increased crop root growth, improved production of lateral roots and root hairs as well

as rooting depth and root density in the profile by increasing soil N availability for

longer time.

Nash et al. (2013) reported that broadcast and strip-till placement of polymer

coated urea (PCU) produced taller plants than the non-treated controls. Plant

population increased with PCU (8,400 plants ha-1) compared to no coated urea (8,100

plants ha-1) with both strip till and no-till placement.

Strey and Christians (2013) observed that Kentucky bluegrass turf gave best

response for polymer coated urea XCU (43-0-0) as compared to Polyon (44.5-0-0) on

the basis of mean visual response likes colour, quality and uniformity. But, XCU at

the 1-lb rate showed significantly better response than the XCU @ 2 lb N 1,000 ft-2.

Hatfield and Parkin (2014) revealed that use of enhanced efficiency fertilizers

(EEFs) in maize resulted in an increased greenness in canopy, delayed senescence of

the plant, increased chlorophyll index or the plant senescence index and the duration

of green leaf area during the grain-filling stage.

Field studies were conducted by Qin et al. (2014) from 2009 to 2012 near

Lethbridge, AB, Canada, to determine how upper limits of seed safety using seed-

placed environmentally smart nitrogen fertilizer (ESN) in cereals and canola change

with increased N rates and alterations to the coating integrity of ESN. The findings

from this study indicate that safe (no yield reduction) seed-placed rates could be

increased to 60 kg N ha-1 for canola and up to 90 kg N ha-1 for spring cereals if ESN is

handled properly to maintain coating integrity within N release range of 20 to 40%,

but safe limit for seed-placed urea was generally 30 kg N ha-1.

A 3-yr study was conducted on a sandy-loam soil in Quebec, Canada, to

examine the effect of PCU application rate (0, 60, 120, 200, and 280 kg N ha–1) on

petiole NO3–N concentrations, chlorophyll meter readings (SPAD readings), soil

mineral N content, and total tuber yield (Cambouris et al., 2014). The NO3AEM values

(NO3 adsorbed by anion exchange membranes), petiole NO3–N concentrations, SPAD


~ 10 ~

readings, soil mineral N content, and total tuber yield increased with PCU application

rate. The NO3AEM values fluctuated during the growing season due to plant N uptake

and variations in soil moisture content.

From the research studies carried out in a greenhouse by Pinpeangchan and

Wanapu (2015) it was found that encapsulated urea fertilizers (EUFs) increase fresh

weight, root fresh weight, stem dry weight and root dry weight of kale plant. Stem

length showed a significant difference at P value ≤ 0.05 highest in urea, EUF-2

(PVA/PVP=1:0), EUF-3 (PVA/PVP=1: 0.25) and EUF-6 (PVA/PVP=1:2). Plants

with control, osmocote, polyvinyl alcohols (PVA) and poly vinyl pyrrolidone (PVA)

resulted in lowest stem and root dry weight. Application of coated urea slightly

increased leaf area, while control, osmocote, PVA, and PVP had smaller leaf area.

2.3 Effect of polymer coated urea (PCU) on Yield attributes

Trials with maize and sugarcane (Bishop, 1993) showed that prills of urea or

LAN (limestone ammonium Nitrate) coated with 0.5% of a styrene-octyl acrylic

polymer initiated substantially more plant leaf N and more corn grain in recently tilled

soils and higher estimated recoverable sugar (ers) % cane and fibre % cane values in

ratoon crops than equivalent uncoated commercial. Coated LAN (limestone

ammonium Nitrate) gave more cane and more ers ha-1 than commercial LAN. Of the

two coatings, one of 0.5% polymer tested with ratoon cane encouraged both

vegetative growth (tons cane ha-1) and earlier maturity (higher ers % and fibre %

cane) with limestone ammonium Nitrate at both 80 and 120 kg N ha-1, while at the

0.01% polymer level only increase vegetative growth at 80 kg N ha-1.

Singh et al. (1995) reported that grain yield of lowland rice from a single

application of polymer coated urea (PCU) was equivalent to or better than 3-4 time

split application of urea. Fertilizer recovery with PCU was 70-75% compared to 50%

with prilled urea.

Bishop (1998) stated that maize grain yields had a positive correlation with

total rainfall and a negative correlation with leaf Ca (r = -0.5723 NS) and Mg values

(r = -0.5614 NS) with both commercial and coated urea. The more restrained rate of N

release from the fertilizers coated with 0.5% polymer produced hardier, less


~ 11 ~

vegetative crops, lower stover to grain in maize and sugarcane crops with lower ratios

of tons cane to estimated recoverable sugar (ers) % cane than those produced by

commercial N. The crop with polymer coated N mature earlier than commercial N.

The result of an experiment conducted at 2 sites on imperfectly drained soil in

2002 by Schwab and co-workers indicated that with only 60 lbs N/a applied in wheat,

the split product (1/3 urea+2/3 PCU) application produced significantly higher grain

yield than all the other post-plant applications except for urea applied in March. At

Princeton site, the yield of the urea/PCU mix was over 8 bu/a higher than the

traditional split application of urea.

Carreres et al. (2003) concluded that he highest grain yield (9.37 t ha-1) was

obtained with polymer coated urea (PCU 40% N), and then the ranked order was

ammonium sulphate nitrate (ASN) plus dimethyl pyrazole phosphate

(DMPP)> isobutylidenediurea (IBDU)> ASN plus dicyandiamide (DCD)> PCU (32%

N)> sulphur coated urea (MSCU). PCU (40% N) application resulted in a higher

number of spikelets per panicle than any other N source application irrespective of

delay in flooding after N application.

Zvomuya et al. (2003) stated that under leaching conditions (≥ 25 mm

drainage water in at least one 24-h period) and in excessive irrigation, PCU at 280 kg

N ha-1 in ‘Russet Burbank’ potato improved total and marketable tuber yields by 12

to 19% compared with applications of urea in 3 splits.

According to the findings of an experiment conducted at BHU farm by Singh

et al. (2004) it was concluded that co-situs application of iron 75% through pyrite plus

25% through polyolefin resin coated slow release Fe (PRCSRFe) fertilizer sustained

crop productivity in calcareous soil. The highest mean grain and straw yield of 41.46

and 93.195 g hill-1, panicle weight, grain panicle-1, test weight were obtained in paddy

with the application NPK + 75% pyrite + 25% PRCSRFe which was at par with NPK

+ 50% pyrite + 50% PRCSRFe and NPK + 100% PRCSRFe.

Bundy and Andraski (2007) revealed that a single preplant application of

environmentally smart nitrogen fertilizer (ESN) was more effective than sidedress or

split applications of ammonium sulphate (AS) or urea in terms of yield and fertilizer


~ 12 ~

N recovery in both high and normal rainfall years. 4 years of data showed that ESN

was much better as a preplant treatment in wet years than conventional fertilizers in

corn.

Pack et al. (2006) compared Controlled-release fertilizers (CRF) with

ammonium nitrate (AN) in potato (Solanum tuberosum L.) at the University of

Florida farm in Hastings, FL. Treatments were no nitrogen (No-N), AN, and nine

CRFs at 146 and 225kg N ha−1. CRF (225 and 146 kg N ha−1) resulted in highest total

and marketable yields at 33.7 MT ha−1 and 29.4 MT ha−1 respectively.

Worthigton et al. (2007) observed thatplants in controlled release fertilizer

(CRF) treatment produced 12% higher marketable tuber yield with 13% less N

application compared to ammonium nitrate (AN) treatment.

Golden et al. (2009) reported that pre-plant incorporated polymer coated urea

increased rice grain yield and N uptake in the direct seeded, delayed flood method

over urea applied at the five-leaf stage.

Noellsch et al. (2009) found that in maize, pre-plant incorporated polymer

coated urea increased N fertilizer recovery efficiency and grain yield over control in

the clay pan landscapes.

Taysom et al. (2009) reported that both environmentally smart nitrogen

fertilizer (ESN) and urea performed significantly better than the untreated check.

Polymer coated urea (PCU) [67 % of RDF] at emergence in potato produced

significantly highest total tuber yield, US No.1, marketable (including both US No.1&

2) and crop value (gross & net crop value) among all treatment with different

placement method and differs N rates (33%, 67%, 100% and 130% of RDF).

Yield results from three research sites indicated that 38% N PCU fertilizer

produced yields that were comparable, albeit slightly lower (when all three sites are

considered), to urea applied preflood and shows promise as a fertilizer that could

potentially be used in the direct-seeded, delayed-flood rice production system (Slaton

et al., 2009).


~ 13 ~

The result of a trial conducted on potato in 2010 by Rosen and co-workers

showed that the potato tuber yield from dealer grade ESN-C (Environmentally Smart

Nitrogen fertilizer) was numerically higher than that of air boom ESN sample (ESN-

A) by nearly 45 cwt/a (8.5%), but these differences were not statistically significant.

Emergence applied ESN-C also produced significantly higher marketable yields than

the emergence ESN-C/urea blend and higher % of larger tuber (≥10 oz) than control

treatment.

Jun-gang et al. (2010) conducted an experiment in China on summer maize

and observed that the maize grain yields from N fertilized treatments were

significantly increased, which were 9.61 to 10.4 t/ha higher than the controlled

treatment without fertilized (8.71 t/ha). The yield from the PCFN2 treatment (120 kg

ha-1 N) was similar to that of conventional fertilizer treatment (180 kg ha-1 N).

Patil et al. (2010) found that for both the growing seasons in 2006-07, all the

polymer coated urea (PCU) treatments showed better performance than the treatment

with uncoated fertilizer alone (N80C0). Total number of grains per panicle as well as

grain yield in paddy was significantly higher in PCU treatments (N56C39 and N40C20)

than conventional urea treatment (N80C0).

Yi et al. (2011) studied the effects of different dosages of coated controlled

release urea (PCU-60, 60 days release duration) combined with conventional urea (U)

on winter wheat growth and observed that at the same N dosage, all the test indices of

PU4 (40% PCU-60+60% U) were significantly higher. The grain yield, N recovery

rate, total N accumulation amount, total tiller number and aboveground biomass at

ripening stage, and economic benefit increased by 5.6%, 14.6%, 7.2%, 2.6%, 7.5%,

and 984.3 yuan ha-1 respectively over check.

Gagnon et al. (2012) conducted an experiment during 2008-2010 and found

that fertilizer treatments increased corn yield in all 3 yrs. of the study, but the

magnitude of the response varied with years. In the wet years (2008 & 2009) polymer

coated urea (PCU), urea ammonium nitrate 32% (UAN) and nitrification inhibitor

urea (NIU) significantly increased yields by 1.6, 1.4 and 0.6 Mg ha-1 over urea

respectively. Grain N concentration showed linear response with increasing rates of


~ 14 ~

urea and PCU in 2010 and quadratic in 2008 and 2009.In 2008, only polymer coated

urea and urea ammonium nitrate treatments (UAN) @ 150 kg N ha-1 gave higher

grain N than the control.

Ma et al. (2012) studied the effects of sulfur and polymer-coated controlled

release urea fertilizers on wheat yield and its quality. It was found that both sulfur-

and polymer-coated controlled release urea fertilizers raised the grain yield by 10.4%-

16.5%, and the grain protein and starch contents by 5.8%-18.9% and 0.3%-1.4% over

traditional urea fertilizers, respectively.

Nash et al. (2012) stated that fertilized treatments had 550 to 2080 kg ha−1

greater winter wheat grain yield than the uncoated controls regardless of the N

application date in double-cropped winter wheat with soybean. Wheat yields were

generally greater when N was applied at 112 kg N ha−1 compared to 84 kg N ha−1,

except for April applications of N fertilizer sources. The average yield with an

application of 100% NCU (non coated urea) and ammonium nitrate (AN) at 112 kg

ha−1 were similar to 75% PCU + 25% NCU at 84 kg ha−1 .

Nash et al. (2013) conducted a field trail in 2008- 2010 (high rainfall years)

near Novelty and observed that Fall and preplant strip-till placement of polymer

coated urea increased grain yield by 1.2 Mg/ha compared to no coated urea in corn.

Strip-till placement of polymer coated urea synergistically increased yield over un-

coated urea and broadcast applications of PCU or uncoated urea due to increased

stands and possibly due to better plant utilization of the banded N fertilizer.

A 4-yr (2010-13) research was conducted by Nashand his co-workers to

determine yield response of corn to polymer-coated urea (PCU) with subsurface

drainage [free drainage (FD) or managed drainage (MD)] and non-coated urea (NCU)

without drainage (ND) in a claypan soil. Averaged over 2010 to 2013, PCU increased

corn grain yield by 20% compared to NCU, which indicated that PCU mitigated the

high N loss potential in a wet soil environment.

Field experiments were conducted by Farmaha and Sims (2013) during 6 site-

years in Minnesota from 2007 to 2009 to examine effects of a polymer-coated urea

[PCU, environmentally smart nitrogen (ESN)] and non-coated urea on grain yields


~ 15 ~

and protein concentrations of two HRSW cultivars, Alsen and Knudson. The wheat

cultivar Knudson produced greater grain yield. Because of delayed N release from

PCU, greater protein concentration (at physiological maturity, Zadoks scale 92) and

whole tissue N concentration (at the soft dough growth stage, Zadoks scale 85) were

observed with PCU in environments that experienced cool and dry spell in the early

growing season. At the same rates of N, PCU increased protein concentration as

compared to urea, but required higher N rate to maximize grain yield.

Nelson et al. (2014) found that wheat yields were generally greater when

polymer coated urea (PCU) was fall-applied compared to split-applied. In poorly

drained soils wheat grain yield was highest with PCU followed by ammonium nitrate

(AN), urea plus N-(n-butyl) thiophosphoric triamide (U + NBPT) than urea. Polymer-

coated urea is a viable option for fall application to wheat in poorly drained soils.

2.4 Effect of polymer coated urea (PCU) on nutrient uptake

An experimental study was initiated by Schwab and his co-workers in 2002 on

imperfectly drained soils at Lexington and Princeton to compare application timing of

PCU (ESN) and urea for wheat production. N uptake and dry matter accumulation at

flowering stage and N removal by grain were higher in polymer coated urea(PCU)

than urea at 60 lbs N/ac applied before planting. Very low nitrogen use efficiency

(NUE) was observed for urea and ammonium nitrate treatments with (25%) use

efficiency comparative to the fall PCU (> 50%). The average NUE for the pre-plant

treatments was 37% while the post-plant treatment was 56%. The maximum NUE

was measured when a mix of 1/3 urea and 2/3 PCU was applied in February.

Zvomuya et al.(2003) conducted a trial on potato in coarse-textured soil and

fertilizer N recovery efficiency was estimated by the difference and 15N isotope

methods at the 280 kg N ha-1 rate. N recovery efficiency was higher with PCU (mean

50%) than urea (mean 43%).

A trial conducted in the rice field of Valencia (Spain) by Carreres

(2003)showed that polymer coated urea (32% and 40% N) and isobutylidenediurea

(IBDU) application shortly before flooding improved total N uptake and recovery


~ 16 ~

efficiency compared to the conventional fertilizer application, with or without

nitrification inhibitors.

Singh et al. (2004) stated that the different iron sources had a marked effect on

nitrogen, phosphorus, potassium, and iron accumulation by paddy grain, straw as well

as total accumulation by the above ground biological produce and the highest values

were obtained with the application of NPK + 75% pyrite + 25% PRCSRFe.

Tubers from plants under all fertilized treatments removed significantly more

N from the field than tubers from plants under the No-N treatment (Pack et al., 2007).

Plants under TRT-10 (146 kg ha−1 N) and TRT-16 (146 kg ha−1 N) had the highest

nitrogen-removal efficiency (NRE) which were significantly higher than potatoes

under TRT-3 (AN, 225 kg ha−1 N; 24.12%).

Kanno (2008) observed a non-significant difference between the polyolefin

coated urea (POCU-70 and POCU-30+ S60) treatment in total N uptake (TNU) in

corn at all the sampling stages, although the total N uptake by corn plant in 1994 was

significantly higher than 1995. The yearly means of fertilizer-derived N uptake

(FDNU) in the urea, POCU-70 and POCU-30 + S-60 treatments were 77.0, 77.4 and

93.0 kg N ha-1at the harvest respectively.

Junejo et al. (2010) observed that the concentration of Cu and Zn removed by

maize plant was significantly higher in coated urea than uncoated urea treatment.

Total N uptake in plants was found to be in the order of micronutrient coated urea >

gelatin + Cu coated urea > Palm stearin + Cu coated urea > Cu coated urea > Agar +

Cu coated urea > uncoated urea, which was 762, 676, 523, 491, 324 mg pot-1,

respectively.

Patil et al. (2010) reported that the small amount of uncoated urea (as low as

12 kg N ha-1) in coated fertilizer mixture was sufficient to fulfil the initial N

requirement of paddy. After the initial growth stage, plant N concentration (PNC) was

more influenced by coated urea as in 2006, N56C39 and N40C28 at 40 & 47th DAT had

significantly greater PNC than N80C0 and N40C20 treatments.


~ 17 ~

Rosen and co-workers in an experiment on potato in 2010 revealed that mean

concentrations of NO3- in the petiole samples were numerically lowest for the control

on all dates except Aug 12 and significantly lower than those of all treatments on June

7 and June 22.

Sahota et al. (2010) revealed that in winter wheataverage N removal by grain

was 120 kg N/ha which was 7 kg/ha higher with environmentally smart nitrogen

(ESN) than urea. Total N removal by grains + straw was ~180 kg/ha (14 kg/ha higher

with ESN than urea). But in spring wheat there was no significant effect of

environmentally smart nitrogen (ESN) on grain yield, straw yield, plant N content and

grain protein content.

Fageria (2011) reported that NUE was significantly higher at the polymer

coated urea (PCU) as compared to conventional urea. The increase in nitrogen use

efficiency (NUE) by polymer coated urea was about 25% in relation to conventional

urea. The higher nitrogen use efficiency of PCU may be related to the slow release of

N in the soil-plant system according to plant demand and consequently higher

utilization.

Gagnon et al. (2011) reported that in corn, increasing urea rate linearly

decreased apparent N recovery from 50 to 39%. However, this relationship was not

statistically significant with polymer coated urea (PCU) rate. The PCU treatment at

150 kg N ha-1 had higher apparent N recovery than urea.

Ma et al. (2012) reported that controlled release urea fertilizers could sustain

the top soil inorganic N supply to meet the N requirement of the wheat, especially

during its late growth stage. The N use efficiency was enhanced by 58.2% to 101.2%.

Polymer-coated urea produced better wheat yield and higher fertilizer N use

efficiency, compared with sulfur-coated controlled release urea.

Zebarth et al. (2012) stated that plant N uptake was greater under polymer

coated urea (PCU) than under the conventional and split N application in potato,

althoughthese differences were not statistically significant. Petiole NO3-

concentrations and the NNI (Nitrogen nutrition index) were greater for the PCU than

the other two fertilize treatments.


~ 18 ~

2.5 Residual effect of polymer coated urea (PCU)

Junejo et al. (2010) conducted an experiment to determine the residual effect

of coated and uncoated urea on corn biomass. The highest dry matter yield was

obtained from Agar + Cu coated urea (26.5 g pot-1) and this was followed by

micronutrient coated urea, Cu coated urea, gelatin + Cu coated urea, Palm stearin +

Cu coated urea in descending order, while the lowest from uncoated urea (12.5 g

pot-1).

Sahota et al. (2010) studied the residual effectof coated urea on the timothy

crop at Thunder Bay and found that environmentally smart nitrogen (ESN) @ 70 kg

N/ha produced the highest dry matter yield, which was 650 kg/ha higher than urea at

the same rate of N.

The experiment conducted at glass house on corn by Junejo et al. (2010)

revealed higher beneficial residual effects of coated urea on nutrient uptake by plant

as compared to urea alone. Nutrients (Cu & Zn) uptakes were found to be less in

coated urea than urea alone, due to the dilution effect as a result of increase in dry

matter yield. The N uptake of plant was found to be in the order of Cu coated urea >

micronutrient coated urea > gelatin + Cu coated urea > Agar + Cu coated urea > Palm

stearin + Cu coated urea > uncoated urea respectively.

Jun-gang et al. (2010) found that the residual nitrogen was minimum in the

60-90 and 90 -120 cm layer under the conventional fertilizer (180 kg ha-1 N), while it

was significantly higher in polymer coated N fertilizer (PCFN1) with co-situs

placement than that check (no fertilizer) after harvesting of summer maize.

The result of a trial conducted on potato in 2010 by Rosen and co-workers

showed non-significant differences among individual treatments with respect to post-

harvest residual soil N. Mean soil N levels were equivalent to 0.8 to 4.8 lb/acre N for

ammonium and 22.2 and 27.9 lb/acre N for nitrate.

Gagnon et al. (2011) found significant interaction between treatments × year

for the residual soil NO3- after corn harvest in 0 to 15 cm upper layer. Concentration


~ 19 ~

of soil NO3- was increased by the PCU in all the years, (2 kg ha-1 in 2008 to 9 kg ha-1

in 2009 at 150 kg N ha-1 rate).

Fageria (2011) found that Ca saturation, Mg saturation, exchangeable soil Ca

& Mg, base saturation and effective cation exchange capacity were significantly

higher in the treatment which received polymer coated urea as compared to

conventional urea. This may be related to controlled and slowly available Ca & Mg

due to the application of PCU for N.

2.6 Effect of polymer coated urea (PCU) on environment

Zvomuya et al. (2003) found that a single application of PCU improved

recovery of N and reduced NO3 leaching compared to three application of urea. NO3-

leaching during the growing season was lower with polymer coated urea (34 to 49%)

than three split applications of urea in potato field. Under standard irrigation in the

third year, leaching from five split applications of urea (280 kg N ha-1) was 38%

higher than PCU. Similar results were reported by Waddell et al. (2000), comparing

sulphur coated urea SCU with urea.

A trial at the University of Florida research farm in 2004 revealed that

controlled release fertilizer (CRF) rates can be reduced up to 50% compared to

soluble nitrogen sources (a reduction of 100 lb N/acre) without reducing potato tuber

yield and quality (Pack et al., 2006). Nitrate movement data indicated that nitrogen

leaching below the root zone can be reduced by 60-80% compared to conventional

fertilizers

Pack et al. (2007) observed significantly higher concentrations of NO3--N in

the soil solution from suction lysimeters with ammonium nitrate (AN) @ 146 kg

ha−1 N and 225 kg ha-1was 127 mg L−1 NO3--N and 172 mg L−1 NO3

- -N respectively

than with any controlled release fertilizer (CRF) at 39 DAP. Thus it clearly indicated

that any CRF is better than ammonium nitrate in reducing NO3--N in the soil solution.

Nelson et al. (2009) was conducted a trial to evaluate NO3-–N concentrations

in soil water samples and to determine differences in corn yields and N utilization in

non-coated urea (NCU) and polymer coated urea (PCU) treated plots under different


~ 20 ~

water management systems. Water samples from suction lysimeters at a 45 cm depth

in soil treated with PCU had 51 to 63% lower NO3-–N concentration than NCU at 59

days after application (DAA), while NCU had 85 to 92% lower N concentration than

PCU 153 DAA.

Wilson and co-workers (2010) made a comparative study on N leaching with

polymer coated urea (PCU) and urea found that PCU significantly reduced leaching

and improved N recovery over soluble N applied in two splits and resulted in similar

N recovery and nitrate leaching as soluble N applied in six splits. Nitrate leaching

with (Environmentally Smart Nitrogen) ESN (21.3 kg NO3--N ha-1 averaged over N

rates) was significantly lower than with split-applied soluble N (26.9 kg NO3--N ha-1,

but significantly in Apparent N recovery i.e. 65% (averaged over four rates) with

PCU than 55% with split-applied soluble N at equivalent rates (p = 0.059).

The findings of a field trail on turf grass by LeMonte et al. (2011) reported

that with providing an adequate N supply to Kentucky bluegrass/perennial ryegrass,

polymer coated urea(PCU) application resulted in decreased NH3 volatilization by

41–49% compared to urea application. Using uncoated urea as an N fertilizer resulted

in 127 – 476% more measured N2O impact on the environment, whereas PCU was

only 25 – 52% higher (not significant) than background emission levels.

A field study in Utah on polymer coated urea in Kentucky bluegrass and

perennial ryegrass showed reduction in NH3 volatilization by 41-50% compared to

untreated urea (Story et al., 2011). Similar results were observed in a study in Georgia

(Connell et al., 2011).

Of the total global anthropogenic NH3 emission of 43 Tg N yr−1, 12.6 Tg

N yr−1 is from cropland (not including animals on cropland). It was observed that

Polyon, which is a slow release fertilizer, decreased N2O emission by 96% besides

4% CH4 emissions (Linquist et al., 2012).

A 2-year field study was carried out by Yang and co-workers (2013) to

investigate the effect of controlled release nitrogen fertilizer management on nitrogen

loss from paddy field under water saving irrigation and found nitrogen export from

paddy fields to be reduced by 36.3 kg N ha-1 in comparison to farmer practice.


~ 21 ~

Halvorson et al. (2014) observed that environmentally smart nitrogen (ESN)

reduced N2O emissions by 42% compared with urea and 14% compared with urea

ammonium nitrate (UAN) in no-till (NT) and strip-till (ST) with no effect in a

conventional till (CT).

Gao et al. (2014) examined the effect of placement and enhanced efficiency

fertilizers on N2O emissions from spring wheat (Triticum aestivum L.) at two

locations in Manitoba. Total N2O emission from midrow-banded environmentally

smart nitrogen (ESNM) and midrow-banded SuperU (SuperUM) was similar, being 19

and 51% smaller than for midrow-banded urea placement between every other set of

rows (UreaM) at Carman and Oak Bluff, respectively (P< 0.001). The average daily

N2O emission rate for both sites was 30.2 a, 24.7 ab, 21.0 bc, 15.8 cd, 14.6 d and 8.0 e

g N ha–1 day–1 from broadcast-incorporated urea (UreaI), subsurface side-banded urea

(UreaS; each row side-banded), UreaM, SuperUM, ESNM, and Control respectively

with significant (P< 0.10) differences.

Materials and Methods

~ 22 ~

Chapter- III


The present investigation entitled “Effect of polymer coated urea on the

growth and yield of rice[Oryza sativa (L.)]” was conducted during the kharif

seasons of 2014 at the Agriculture Research Farm, Institute of Agriculture Sciences,

Banaras Hindu University, Varanasi. The details of the methods employed and

materials used in the present experiment have been described here. The climate, soil

and crop conditions, cropping history of the experimental area have also been

presented in this chapter.

3.1 Experimental site

The Agricultural Research Farm is situated in the south-eastern part of

Varanasi city at a distance of about 10 km from Varanasi cant railway station.

Geographically, the experimental site falls under sub-tropical zone of Indo-Gangatic

plains and lies on the left bank of river Ganga. It is located on 2518 N latitude,

8303 E longitude and at an altitude of 77 meters above mean sea level. The

experimental plot was homogenous in fertility with assured irrigation and other

required facilities.

3.2 Climatic condition of Varanasi

The weather of Varanasi is categorized under moisture deficit index of 20-40

percent and falls in the belt of semi-arid to sub humid climate having hot summer and

cold winter. The normal period for the onset of monsoon in this region is the third

week of June and it lasts upto the end of September and sometimes up to the first

week of October. A light shower is often experienced in January and February. Month

of March to May are generally dry. The distribution of rainfall is 88% from June to

September, 5.7% from October to December, 3.3% from January to February and 3%

from March to May. The average annual precipitation (P) of Varanasi is 1100 mm and

annual potential evapo-transpiration (PET) is about 1525 mm. The annual moisture

deficit in this region is about 425 mm. The differences between total rain fall received

(about 875 mm) and evaporation losses (about 665 mm) is always positive (about 210

mm) during rainy season (from July-October). However, in the subsequent months


~ 23 ~

from November to June, the differences are always negative. Generally maximum and

minimum temperature ranges between 17.90C to 36.30C and from 9.80 to 28.30C,

respectively. The temperature begins to rise from the middle of February and reaches

its maximum in middle of June. The coldest period of the year is between last week of

December to first week of January. The mean relative humidity is 70 per cent, which

rises up to 94.0 per cent during January and fall down to 42 percent during the end of

April to early June. The detail of meteorological data for the experimental period

(2013-2014) is presented in Table 3.1.

Table 3.1: Weekly meteorological data of Varanasi during experiment period

(June, 2014 to October, 2014)

Week

No.

Month &

Date

Rainfall

(mm)

Temperature

(0C)

R.H.(%) Wind

Speed

km/hr

Sunshine

(hrs.)

Evaporation

(mm)

Max. Min. Morn Even.

23 June 04-10 0.0 43.4 28.3 62 27 3.9 9.5 7.0

24 11-17 5.4 37.6 28.5 64 39 6.6 6.6 7.7

25 18-24 42.9 37.7 27.7 74 44 6.1 3.8 5.1

26 25-01 12.8 38.8 28.5 71 42 3.9 5.2 6.9

27 July 02-08 65.9 33.9 26.6 83 71 4.0 2.2 4.2

28 09-15 0.0 36.7 28.7 79 63 4.8 7.9 5.4

29 16-22 261.5 32.8 26.8 92 84 6.1 1.4 2.8

30 23-29 4.6 33.3 26.6 82 65 2.4 4.8 3.3

31 30-05 46.0 32.8 27.7 87 74 5.4 5.7 4.4

32 Aug 06-12 142.7 32.9 26.4 87 74 5.1 4.1 3.3

33 13-19 42.4 23.6 27.6 86 79 5.4 2.4 2.8

34 20-26 14.0 35.1 27.5 77 60 4.0 6.7 4.4

35 27-02 6.5 33.0 27.1 84 71 7.2 5.3 4.6

36 Sep 03-09 34.9 32.7 26.4 85 69 5.0 6.0 3.0

37 10-16 11.0 31.9 25.8 91 80 1.8 4.0 3.1

38 17-23 13.7 33.3 26.0 87 72 1.6 5.2 3.4

39 24-30 2.1 33.4 24.3 85 56 3.6 9.3 4.1

40 Oct 01-07 0.0 32.2 24.2 79 64 1.2 7.2 3.1


~ 24 ~

Fig. 3.1: Standard weekwise Meteorological Observations recorded at the Meteorological Observatory of the Department of Agronomy,

I.Ag. Sc., BHU during the period of experimentation (June, 2014- October, 2014)

0

1

2

3

4

5

6

7

8

9

10

0

50

100

150

200

250

300

23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40

Standard week

win

d s

pe

ed

, s

un

sh

ine

, e

va

po

rati

on

Rain

fall

, T

em

pe

ratu

re, R

H

Rainfall (mm) Max Temp. (0C) Min Temp. (0C) Morn. RH (%)

Even. RH(%) wind speed (km hr-1) sunshine (hrs) evaporation (mm)


~ 25 ~

The details of different weather parameters during the period of experiment are given

below:

3.2.1 Temperature (0C)

The weekly mean minimum and maximum temperature during the

experimentation ranged from 24.20C to 28.70C and 23.60C to 43.40C, respectively.

The maximum temperature 43.40C was recorded in 23rd standard week in the month

of June 2014 whereas; the lowest minimum temperature remained 24.2C in the 40th

standard week of October.

3.2.2 Rainfall (mm)

The cumulative rainfall during the period of investigation in the cropping year

2014 (20th June-1st October) was 706.4 mm.The pattern of rainfall distribution was

erratic during the experimental period with the highest rainfall (261.5 mm) being

observed during 29th week of the year in July.

3.2.3 Sun-shine duration (hrs)

The average duration of bright sunshine was 5.41 hours. The maximum and

minimum weekly bright sunshine duration ranged between 9.5 to 1.4 hours,

respectively during the period of investigation.

3.2.4 Relative Humidity (%)

The weekly morning relative humidity ranged between 62% (04-10 June) to

92 % (16-22 July) and evening relative humidity varied from 27% (04-10 June) to

84% (16-22 July) during the period of investigation.

3.2.5 Evaporation (mm)

The evaporation data obtained from weather bureau class A Pan Evaporimeter

revealed that the average evaporation during the crop period varied from 2.8 to 7.0

mm day-1.


~ 26 ~

3.3 Soil

Varanasi lies almost in the middle of the Indo-Gangetic alluvial plainsand the

soil is typically Gangetic alluvium (order-inceptisol). These soils are deep, low in

available nitrogen and medium in available phosphorus and potassium. The soil of the

experimental field was sandy clay loam in texture with its natural drainage facilities.

Before the start of experiment, composite soil samples were collected with the help of

auger and core sampler and the soil samples thus obtained were subjected to various

electro-chemical and biological analyses which is as follows.

Table 3.2: Mechanical and chemical soil analysis of the experimental plot

Particulars Before

sowing

After

harvesting

Method employed

(A) Mechanical analysis

Hydrometer method

(Bouyoucos,1962)

Soil separates

1. Coarse sand (%) 8.28 8.27

2. Fine sand (%) 52.4 52.4

3. Silt (%) 19.5 19.4

4. Clay (%) 18.5 18.5

5. Texture class (%) Sandy clay

loam

Sandy clay

loam

(B) Physical analysis

Bulk density (gcc-1) 1.35 1.35

(C) Chemical analysis

Electrical conductivity

(dsm-1 ) at 250C

0.29 0.29 Conductivity bridge

(Jackson,1973)

Soil pH (1:2:5 soil and water

suspension)

7.4 7.5 Glass electrode digital pH

meter (Jackson,1973)

Organic carbon (%) 0.38 0.38 Walkley and Black’s Method

(Jackson,1973)

Available Nitrogen (kg ha-1) 179 188 Alkaline permanganate

(Subbiah and Asija,1956)

Available P2O5 (kg ha-1) 18.0 18.4 0.5N NaHCO3 extractable

(Olsen et al.,1995)

Available K2O (kg ha-1) 199.6 199.0 Ammonium acetate

extractable flame photometer

(Jackson,1973)

3.4 Experimental design and layout

The experiment consisting of 5 treatments was laid out in a Randomized

Complete Block Design with four replications and conducted in open bottom circular


~ 27 ~

cemented pots having diameter of 60 cm. The height of each pot was 25-30 cm and these

were buried half in field at a depth of 12-15 cm.

3.3 (a) Treatment details:

U0 - Urea super granules

U1 - Polymer coated urea (single coating)

U2 - Polymer coated urea (double coating)

U3 - Neem coated urea

U4 - Sulphur coated urea

Table 3.3 (b): Details of layout.

Site : B.H.U., Varanasi, UP

Design : Randomized Complete Block Design

Treatment : 5

Replication : 4

Pot size : 1926 cm2

..……………………….FARM SUB ROAD ……………………….

R-I R-II R-III R-IV

U2 U4 U2 U1

U0 U1 U0 U3

U4 U3 U4 U0

U1 U0 U1 U2

U3 U2 U3 U4

Fig. 3.2: Layout plan of pot experiment

N

S

W E


~ 28 ~

3.5 Selection of experimental materials

3.5.1 Selection of crop variety

NDR-97 selected for the study is an early maturing varietyof rice which matures in

about 90-100 days. Plants are of medium statured with dark green foliage and high

yield potential (3.0-4.0 t ha-1).

Important attributes:

Parentage : Nagina-22 ×Ratna

Released in : 1992

Breeding : Hybridization & Pedigree method selection

Height : 80-85 cm

Maturity : 90-100 Days

Tillering : 8-15 tillers

Lodging : Lodging resistant

Flowering : Flowering in 70 days

Panicle : Medium (18-25 cm, drupes) due to erect study plant

stature

Grain type : Long -slender

Yield : 30-40 q/ha

Resistant /Tolerant : Brown spot, blast and seed rot

3.5.2 Source of nutrients

In rice crop, a uniform recommended dose of 102 kg N, 60 kg P2O5 and 60 kg

K2O ha-1 was applied to all the plots. Phosphorous and potassium were applied

through Diammonium Phosphate (2.5g) and Muriate of Potash (2g) as basal

application at transplanting respectively. The coated urea fertilizers like polymer

coated urea (PCU), neem coated urea (NCU), sulphur coated urea (SCU) and urea

super granules (USG) were applied a week after transplanting to supply nitrogen


~ 29 ~

needed by plant during its entire growth period. 2g of these coated urea fertilizers

were deep-placed at 7.5 cm at the center of four hills.

3.5.2.1.1 Urea super granules (USG)

Urea super granules are large urea granules of about ≥1 gram developed for the

purpose of enhancing NUE. They are primarily intended for wetland transplanted rice

grown on puddled soil. Deep placement of USGs resulted in higher grain and straw

yield as well as better nutrient uptake in lowland paddy.

3.5.2.2 Sulphur coated urea (SCU)

Sulphur-coated urea (SCU) was developed at the TVA in 1961. It is prepared

by spraying molten sulphur over granular urea to yield a product containing

between31 to 38% N. A wax sealant is then sprayed to seal cracks in the coating

andto reduce leakage and microbial degradation of the S coating (Shaviv, 2000).

Release of nutrients is controlled by physical breakdown of coatings, microbial

decomposition of the sulphur and hydrolytic cleavage of S-S linkages. Jarrell and

Boersma (1980) suggested an Arrhenius-type expression for the model pertaining to

the effect of temperature on nitrogen release from sulphur-coated urea (SCU).

3.5.2.3 Neem coated urea (NCU)

Techniques for preparing neem coated urea were developed at IARI, New

Delhi. One technique is coating urea with neem cake byusing a coal-tar kerosene

mixture and by neem oil micro-emulsion (Suri et al., 2000). The oil obtained from its

fruits and the press cake from the production of neem oil was used for the production

of neem coated urea (NCU). This has been adapted by several companies in India and

is sold as neem coated urea. Prasad et al. (2002) reported the superiority of NCU over

conventional urea for rice. Field trials by National Fertilizers Limited showed a yield

increase of 10.4 % in Haryana, 9.6 % in UP and 14 % in Punjab over prilled urea.


~ 30 ~

3.5.2.3 Polymer coated urea (PCU)

Polymer coated urea is one of the controlled release fertilizers which is a new

approach in agriculture for enhancing nitrogen use efficiency and sustaining yield.

Polymer coated urea are prepared by coating urea granules with polyethylene,

polyester and other biodegradable polymers likes polylactic acid (PLA),

polyhydroxyalkanoate (PHA), poly vinyl alchohol and polycaprolactone. Polylactic

acid (PLA) is at present one of the most promising biodegradable polymers

(biopolymers) and can be processed with a large number of techniques and is

commercially available (large-scale production) in a wide range of grades (Avérous,

2008).

Polylactic acid (PLA) is a polymer of lactic acid with higher molecular

weight. PLA belongs to the family of aliphatic polyesters commonly made from

hydroxy acids that includes, for example, polyglycolic acid (PGA). It is one of the

polymer in which the stereo-chemical structure can easily be modified by

polymerizing a controlled mixture ofl and d isomers to yield high molecular weight

and amorphous or semi-crystalline polymers. Properties can be both modified through

the variation of isomers (l/d ratio) and the homo and (d, l) copolymers relative

contents. Moreover, PLA can be tailored by formulation involving addition of

plasticizers, other biopolymers, fillers, etc. (Avérous, 2008).

3.5.2.3.1 Preparation of Polylactic acid polymer coated urea fertilizers

Urea granules are coated by solution method, reactive layer coating technique

and thermoplastic resin coating. PLA coated urea are prepared by solution method.

For preparing PLA coated urea, a solution of poly lactic acid was prepared and urea

granules were dipped in solution as it completely adheres round the granules/particles

and then it is dried.

3.6 Cultivation practices

Detail of the operations carried out to get the field prepared for rice during the

entire period of investigation are described below and calendar of field operations are

given in Table 3.4.


~ 31 ~

Table 3.4: Schedule of field operations carried out during experiment

S. No. Operations Date

1. Nursery raising

a) Pre sowing irrigation 20-06-2014

b) Ploughing 22-06-2014

c) Puddling 24-06-2014

d) Manuring 25-06-2014

e) Sowing 25-06-2014

f) Irrigation

1st 25-06-2014

2nd 2-07-2014

3rd 10-07-2014

2. Layout of experiment

Pot establishment 11-07-2014

Pot filling 11-07-2014

3. Puddling 15-07-2014

4. Transplanting 15-07-2014

5. Fertilizer application

a) Basal application of NPK 15-07-2014

b) Deep placement of coated urea 22-07-2014

8.

a)

b)

Weed management (hand weeding)

1st hoeing

2nd hoeing

30-07-2014

30-07-2014

20-08-2014

9. Irrigation

Every day the pots were irrigated to maintain

suitable moisture content in soil for plant growth

10. Harvesting 01-10-2014

3.6.1 Nursery raising

A small plot of 25 m2 was selected for growing rice seedlings. The nursery

area was ploughed thrice, levelled and desired seedbed was prepared. Soil moisture

condition favourable to seedling growth was provided and bed was uniformly

fertilized. Certified seeds of rice genotype ‘NDR-97” were soaked in water for 12

hours and subsequently sown in the nursery on puddled bed by broadcast method


~ 32 ~

adopting the recommended seed rate of 30 kg ha-1. Small amount of water was

sprinkled over the nursery area for two days and thereafter it was drained off.

Optimum soil moisture was maintained in the nursery for good growth of seedlings.

3.6.2 Pot preparation

Good soil preparation provides chance for good growth of rice plant. The soil

of the pots was puddled manually by using kudal, levelled with a thin film of water at

its surface.

3.6.3 Transplanting

One day before transplanting, nursery bed was irrigated to maintain soft soil to

prevent tearing of seedling roots. Seedlings were uprooted carefully from the nursery

bed and 25 days old seedlings were transplanted in the puddled pots at the rate of two

to three seedlings hill-1and four hills pot-1. Row spacing of 15 cm and hill-to-hill

distance 15 cm were maintained. Gap filling was done, if required.

3.6.4 Irrigation

Irrigation water was supplied to the experimental crop as per needs at different

stages of crop growth.

3.6.5 Weed management

Management of weeds was done only by hand weeding at 15 DAT and 35

DAT.

3.6.6 Harvesting

The crop was harvested at maturity stage, when most of the panicles turned

golden yellow. All four hills of each treatment were harvested separately. The

harvested hills were carefully bundled, tagged and fresh weight was taken.


~ 33 ~

3.6.7 Threshing

Threshing was done pot wise. The bundles of each plot were threshed

separately with the help of thresher and grains thus collected were cleaned and

weighed with the help of spring balance separately for each pot and computed to g

hill-1 at 12% moisture level. The straw yield was also recorded pot wise and

calculated in terms of g hill-1.

3.7 Observations on coated urea fertilizers

3.7.1 Soil nitrogen analysis

Soil nitrogen content was recorded at 3 days intervals after application of

coated urea fertilizers upto 41 days after placement of fertilizers. Soil samples were

collected from soil between four hills where coated urea fertilizers were deep placed

to assess the nitrogen releasing from these products in unit time interval.

3.8 Biometric observations

For recording biometric observations at a regular interval of 30 days i.e. 30th,

60th day after transplanting and at harvest. Yield attributes and yield were studied

before and after harvesting.

3.9.1 Growth attributes

3.9.1.1 Plant height

Height of individual hill from each pot was measured with the help of meter

scale from the base of the plant to the tip of upper most leaf of the plant before panicle

emergence and upto the tip of panicle after heading, averaged and expressed as

average plant height in cm.

3.9.1.2 Number of tillers per hill

Total tillers per hill were countedfrom each pot separately and expressed as

average number of tillers per plant.


~ 34 ~

3.9.1.3 Number of functional leaves per hill

The number of green leaves (3/4 of leaf length) were counted from all four

hills of each pot separately, averaged and expressed as average number of leaves per

hill.

3.9.1.4 Chlorophyll content

Chlorophyll content of 10 randomly selected fully grown leaves per pot was

recorded by using SPAD meter (soil-plant analysis development).

3.9.2Yield attributes

3.9.2.1 Number of panicles per hill

Numbers of panicle per hill were counted from all four hills of each pot

separately and was expressed in average number of panicles per hill.

3.9.2.2 Panicle length (cm)

From each pot 10 panicles were selected randomlyand the panicle length was

measured from base to the tip of the panicle and the average length of panicle was

calculated.

3.9.2.3 Grains per panicle

The panicles used for computing length were threshed separately for each plot

and the number of grains per panicle was worked out.

3.9.2.4 Test weight (g)

Grain samples were obtained from cleaned produce of each pot and 1000

grains were counted and weighed.

3.9.2.5 Grain and straw yield (g/hill)

Grain and straw yield were recorded from the hills harvested from each pot.

The threshing of individual hill was done separately and the weight of grain and straw


~ 35 ~

were recorded for each hill after drying to bring the moisture content at a standard

level of 12% and then converted into g hill-1.

For recording straw yield, grain yield was deducted from dry weight of each

hill. The weight thus obtained, converted into g hill-1.

3.9.2.6 Harvest Index (HI)

The harvest index was computed in terms of grain yield expressed as

percentage of biological yield (grain + straw) based on the per hectare yields as

described by Donald, (1968).

Harvest Index (HI) =

Economic yield (grain) [kg ha-1]

× 100

Biological yield (grain+straw) [kg ha-1]

3.9.2.7 Biological yield:

Biological yield = Grain yield + straw yield

3.9.3 Plant and grain analyses

For chemical analysis plant samples, as per treatment, were taken at harvest of

crop. Samples were cleaned properly by repeated washing followed by 0.1N HCl,

solutions. Finally all the samples were subjected to washing by doubled distilled

water. Samples were then dried under shade followed by hot air oven at 60± 10 C for

48 hrs. After drying samples were weighted and grounded in Willey’s Mill as par

treatment separately and stored in butters paper cover. Sample was than subjected to

chemical analysis for Nitrogen, Phosphorus and Potassium content.

The nitrogen content in grain and straw was estimated by modified Kjeldhal

method, while phosphorus was estimated by Vandomolybdate method and potassium

by flame photometer method.


~ 36 ~

Table 3.5 Method of chemical analysis

Analysis Method Reference

Nitrogen Kjeldahl method Jackson, 1973

Phosphorus Vanadomolybdo-phosphoric acid yellow

colour method

Jackson, 1973

Potassium Flame photometer method Jackson, 1973

3.9.3.1 Nutrient (N, P, K) removal by grain and straw (g hill-1)

Nutrient (N, P and K) removal by grain and straw of rice crop was calculated

in g hill-1 in relation to dry matter production ha-1 by using the following formula.

3.9.3.2 Protein content in grain

The percentage of protein content in grain was estimated by multiplying

nitrogen content by a factor of 6.25 (A.O.A.C., 1960).

Protein content in grain (%) = N content in grain (%) × 6.25

3.10 Statistical analysis

All the data obtained from the experiment were put to statistical analysis by

method of ‘Analysis of Variance’ as suggested by (Gomez and Gomez, 1984).

The significant differences were checked with the help of F-test (Variance

ratio) of Fisher (1958). In order to compare the mean value of treatment, standard

error and critical values were calculated. The following formula was used for standard

error, critical difference and coefficient of variance estimations.

Removal (g hill-1) = Nutrient (%) in grain/straw × grain/straw yield (g hill-1)

100


~ 37 ~

a) SEm± = √Ems/r

b) CD = 2Ems × t5% or SEd × t5%

r

b) C.V. (%) = √EmsGM

× 100

Where,

DF = Degree of freedom,

C.D. = Critical difference,

S.S. = Sum of square,

Ems = Error mean square,

r = Number of replication

C.V. = Coefficient of variance,

S.Em± = Standard error of mean

t5%= t value at 5% level of significance from T table at corresponding error df.

Chapter IV

EXPERIMENTAL FINDINGS

In this chapter an attempt has been made to present the experimental findings

of different characters related to the crop and soil nitrogen status at specific interval

after application of urea during the course of investigation. The experiment entitled

“Effect of polymer coated urea on the growth and yield of rice (Oryza sativa L.)”

was conducted in pot during the kharif season of 2014 at the Agricultural Research

Farm, Institute of Agricultural Sciences, Banaras Hindu University, Varanasi, Uttar

Pradesh (India).

During the course of investigation, observations on nitrogen analysis of soil with

different coated urea fertilizers such as polymer coated urea (single coated & double

coated), neem coated urea, sulphur coated urea and urea supergranules were recorded

at 3 days interval after deep placement. Different characters of rice were also recorded

at 30, 60 days after transplanting and at harvest. Observations pertaining to yield and

yield attributes were recorded at harvest. Statistically analyzed data have been

organized in relevant tables with graphical illustrations provided wherever necessary.

4.1 Studies on nitrogen

The nitrogen status of soil with different coated urea and urea supergranules

were recorded at 3 days interval after application. Uptake of nitrogen, phosphorus and

potassium by crop were recorded at harvest.

The study on nitrogen analysis of soil after application of coated urea

presented in Table 4.1 revealed that there was significant difference among treatments

on N content in soil at all the dates of observation that was taken at every 3 days

interval after the deep placement of urea particles. There was no significant difference

between polymer coated urea having both single layer and double layer in N content

just after the application up to 23 days and then significant difference in terms of

release rate was observed. Double layer polymer coated urea released N with slower

rate than single layer coated PCU, but availability of nitrogen was there, for quite

longer period.

Experimental Findings

~39~

The data clearly revealed that N status of soil analyzed at 3 days interval

significantly increased till maturity of crop with application of polymer coated urea,

while plant showed deficiency in later stage of growth with simple urea. Initially

polymer coated urea (PCU) released N slowly upto 3 week thereafter rapid release

was noticed, whereas in case of urea supergranules most of N was released within 20

days after application.

4.2 Observation on crop

4.2.1 Plant height (cm)

The data related to the plant height as influenced by various treatments

presented in the Table 4.2 revealed that the plant height increased consistently with

the advancement of crop age. The treatments significantly influenced the plant height

at all the stages of crop growth.

The data clearly showed that maximum plant height was recorded with the

application of double layer polymer coated urea [PCU (double layer)]. Plant height

was found minimum with uncoated urea i.e. urea supergranules, whereas neem coated

urea remained at par with sulphur coated and polymer coated urea (single layer) at

harvest.

4.2.2 Number of tillers per hill

The data pertaining to the effect of coated urea on number of tillers hill-1 have

been presented in Table 4.3.

In general, the tiller production per hill increased up to 60 days after

transplanting and there after it declined due to mortality of younger tillers irrespective

of the treatment.

It is apparent from data that the nitrogen source significantly differed among

themselves with respect to tiller production at different stages of observation. The

number of tillers increased significantly with availability of nitrogen to plant from

tiller formation to reproductive stage and was found maximum with polymer coated


~40~

urea (double layer) followed by single layer polymer coated urea (PCU, single layer),

neem coated urea (NCU) and sulphur coated urea (SCU) respectively, while minimum

was found with deep placed urea supergranules. Neem coated urea was superior to

urea supergranules, but remained at par with sulphur coated urea and PCU (single

layer) during entire growth period.

There were 24.33, 16.47, 16.02 and 9.09 per cent increase in tiller number with

deep placement of PCU (double coated) over uncoated control (urea supergranules),

sulphur coated urea, neem coated urea and PCU (single coated) respectively at

harvest.

4.2.3 Number of leaves per hill

It is evident from data (Table 4.4) that number of leaves increased as the

growth progressed up to 60 days. However, the rate of increase in number of leaves

remained slower from 30-60 DAT after which it decreased markedly at harvest.

The no. of leaves hill-1 was found to be significantly different among the

sources at different stages of observation. A review of data clearly indicated that deep

placement of PCU (double coated) @ 2g at the center of four hills produced

significantly more number of leaves per hill over all the treatments during the whole

crop period. Number of leaves per hill with neem coated urea (NCU) was at par with

sulphur coated urea (SCU) at 30 & 60 DAT and with polymer coated urea (single

layer) at 30 DAT and harvest. More number of green leaves was observed with coated

urea till maturity of crop, whereas plant with uncoated urea showed yellowish leaves

at later stage of growth.

4.2.4 Chlorophyll content (SPAD)

The data related to the content of chlorophyll in leaves as influenced by

various treatments are presented in Table 4.5.

A cursory glance of data revealed that maximum content of chlorophyll was at

30 DAT as compared to other crop growth stages i.e. at 60 DAT and harvest.

However, there was no significant difference among treatments in chlorophyll content


~41~

of leaves at 30 DAT, but chlorophyll content in leaf was significantly higher with

PCU (double layer) than other treatments at harvesting.

4.2.5 Fresh weight (g hill-1)

The data related to the fresh weight of hill at harvest as influenced by various

treatments are presented in Table 4.6.

Perusal of data revealed marked increase in fresh weight of crop per hill at

harvest. The fresh weight of crop was found to be maximum with polymer coated

urea (double layer) over all other treatments.

The fresh weight of crop was 143.96, 157.5, 138.36 and 133.32 and 121.21

g hill-1 with application of PCU (single coated), PCU (double coated), neem coated

urea and sulphur coated urea and untreated control respectively.

4.2.6 Dry weight (g hill-1)

The data related to the dry weight per hill as influenced by various treatments

are presented in Table 4.6

It is apparent from the data that the dry matter production differed

significantly due to different source of N fertilizers. PCU was significantly superior to

all other treatments in respect to dry matter accumulation.

The perusal of data indicated that deep placed polymer coated urea (PCU)

showed higher dry matter accumulation compared to other treatments. Neem coated

urea remained at par with sulphur coated urea with 105.21 & 102.71 g hill-1 dry

weight respectively, at harvesting. Minimum dry matter accumulation was recorded

with urea super granules (93.89 g hill-1).

There were 32.41, 20.24, 12.06 and 9.39 per cent increase in dry weight with

coated urea viz. double layer polymer coated urea (PCU), single layer polymer coated

urea, NCU (neem coated urea) and SCU (sulphur coated urea) respectively over

uncoated urea super granules.


~42~

4.2.7 Yield attributes

4.2.7.1 Number of effective tillers per hill

Data pertaining to the effect of source of nitrogen on number of effective

tillers per hill have been presented in Table 4.3.

Perusal of data shows that number of effective tillers significantly increased

with coated nitrogenous fertilizer as compared to uncoated urea. Deep placement of

double coated PCU fertilizer recorded highest number of effective tillers per hill,

while neem coated urea remained at par with sulphur coated urea and PCU (single

layer).

4.2.7.2 Panicle length (cm)

The data on panicle length (cm) are presented in Table 4.7. Data shows that

sources of N have significant effect on length of panicle.

Data shows that application of polymer coated urea (double layered) recorded

maximum panicle length (20.14 cm) but at par with PCU (single layered) and neem

coated urea. The length of panicle was found to be minimum in uncoated urea

supergranules (18.26 cm) which was at par with the sulphur coated urea fertilizer

(18.52 cm).

4.2.7.3 Panicle weight (g panicle-1)

The data on panicle weight shows that sources of N have significant effect on

weight of panicle (Table 4.7).

An examination of data revealed that highest value of panicle weight was

observed with deep placed double layer polymer coated urea followed by single layer

polymer coated urea, neem coated urea, sulphur coated urea and urea supergranules

respectively.


~43~

4.2.7.4 Number of grains per panicle

A critical study of the data on number of grains per panicle has been presented

in Table 4.7.

Perusal of data reveals that the maximum number grains panicle-1 was

recorded with the treatment in which polymer coated urea was deep placed at the

center of four hills. All the coated urea treatment recorded significantly higher

number of grains per panicle than uncoated urea (urea supergranule). No significant

difference was observed between neem coated and sulphur coated urea in producing

grains per panicle.

Deep placed PCU both double layer and single layer increased 16.07 and 9.38

per cent grains per panicle respectively over uncoated urea.

4.2.7.5 Test weight (g)

A critical study of the data presented in Table 4.7 revealed that the treatments

did not have any significant effect on test weight of grain. There was no significant

difference of coated urea on 1000 grain weight than the uncoated urea.

4.2.8 Effect of treatments on yield

The data pertaining to effect of different sources of N on grain and straw yield

expressed in g hill-1 (Table 4.8).

An examination of data revealed that polymer coated urea showed superiority

over uncoated urea in respect of grain, straw and total biological yield.

4.2.8.1 Grain yield (g hill-1)

The data pertaining to effect of different treatments on grain yield in g hill-1

presented in Table 4.8.

The highest grain yield per hill (54.39 g/hill) was recorded in the treatment in

which double layered polymer coated urea was deep placed at the mid of four hills,


~44~

while minimum grain yield (39.43 g/hill) was recorded in uncoated urea. Overall

23.89, 37.94, 14.53 and 10.58 per cent increase in yield was observed by PCU (single

layered), PCU (double layered), NCU and SCU respectively over control (uncoated

urea supergranules).

4.2.8.2 Straw yield (g hill-1)

A cursory glance of data on straw yield showed similar results to the grain

yield as presented in Table 4.8.

Deep placement of polymer coated urea (double layer) showed superiority

over untreated control in respect of straw yield, whereas neem coated urea treatment

remained at par with sulphur coated urea only. The increase in straw yield by the

application of PCU (single layer) and PCU (double layer) over urea supergranules

was found to be 17.59% and 28.41% respectively.

4.2.8.3 Total biological yield (g hill-1)

The data pertaining to effect of different treatments on total biological yield in

g hill-1 presented in Table 4.8.

Perusal of data reveals that maximum biological yield was found in double

layer polymer coated urea application which was at par with PCU (single layer) and

significantly superior to other treatments, while deep placement of neem coated urea

was at par with sulphur coated urea. Lowest biological yield was recorded with urea

supergranules.

There were 32.41, 20.24, 12.06 and 9.39 per cent increase in total biological

yield with double layer PCU over all other treatments urea supergranules, sulphur

coated urea, neem coated urea and polymer coated urea (single layer) respectively.

4.2.8.4 Harvest Index (%)

The data on harvest index as influenced by various sources of nitrogen have

been presented in Table 4.8.


~45~

Among all the treatments, maximum harvest index (43.75%) was recorded

with the application of polymer coated urea (double layer), but it remained

statistically at par with all other treatments.

4.2.9 NPK content and uptake by crop

Data related to NPK content (%) in grain and straw and their uptake by crop

(g hill-1) at harvest presented in Table 4.9, 4.10 and 4.11.

Improvement in nutrient content and their uptake by the application of

polymer coated urea was found to be higher than uncoated urea.

4.2.9.1 Nitrogen content and uptake by crop

The data pertaining to N content (%) in grain and straw and its uptake by crop

(g hill-1) presented in Table 4.9, 4.10 and 4.11.

An examination of data revealed that nitrogen content and uptake of nitrogen

was maximum with polymer coated urea which remained significantly superior to

uncoated urea (USG). The percent N content in grain with PCU (double layer) was

highest (1.13%). Uptake of nitrogen by plant was 1.18, 1.33, 1.05, 1.00 and 0.88

g hill-1 with the application of polymer coated urea (single layer), polymer coated urea

(double layer), neem coated urea, sulphur coated urea and urea supergranules

respectively.

4.2.9.2 Phosphorus content and uptake by crop

The data on P content (%) in grain and straw and uptake by crop (g hill-1)

presented in Table 4.9, 4.10 and 4.11 indicate that uptake of phosphorus by hills was

affected by sources of nitrogen. Maximum uptake of P was observed in polymer

coated urea (double layer).

Phosphorus uptake expressed in g hill-1 was 0.20, 0.17, 0.15 and 0.14 with

PCU (double layer), polymer coated urea (single layer), SCU and NCU respectively.


~46~

4.2.9.3 Potassium content and uptake by crop

A cursory glance of data pertaining to K content (%) in grain and straw and its

uptake by crop (g hill-1) has been presented in Table 4.9, 4.10 and 4.11.

It is revealed that potassium content of grain and straw was affected by coated

urea. The highest uptake of potassium by grain and straw was observed under the

polymer coated urea (double layer) followed by polymer coated urea (single layer),

neem coated urea (NCU) and sulphur coated urea (SCU) respectively, while minimum

was observed in uncoated urea supergranules (USG). The per cent increase in uptake

of potassium by plant was 47.78 and 31.11 with PCU (double layer) and PCU (single

layer) respectively over control.

4.2.10 Protein content in grain (%)

Summary of the data on protein content in grain of rice as influenced by

different treatments have been given in Table 4.12.

Significant variation in protein content in grain was obtained due to different

sources of N. Application of PCU (double layer) @ 2g per four hills showed

significantly higher protein content than other treatments except single layer PCU

(U1). Minimum content of protein was found with urea supergranules (6.83%).

Table 4.1: Effect of different treatments on nitrogen content in soil at 3 days intervals

Treatments

N content in soil (kg ha-1)

2

DAA

5

DAA

8

DAA

11

DAA

14

DAA

17

DAA

20

DAA

23

DAA

26

DAA

29

DAA

32

DAA

35

DAA

38

DAA

41

DAA

U0 224.47 227.60 234.50 247.35 258.33 267.73 273.38 267.73 259.26 254.25 251.11 246.41 241.40 235.75

U1 219.76 219.76 220.39 222.59 223.21 225.72 227.60 230.11 235.13 242.96 251.43 262.72 267.11 271.49

U2 219.76 219.76 219.76 221.96 222.59 223.21 226.35 228.23 231.37 235.75 241.40 249.55 255.82 262.09

U3 219.76 222.59 225.09 228.86 234.50 241.39 247.67 255.82 263.03 269.30 274.31 269.30 260.21 252.68

U4 221.33 223.84 226.97 230.74 238.57 246.41 256.13 266.79 273.37 266.79 259.58 252.99 243.91 238.89

SEM 0.30 0.24 0.56 0.65 0.44 0.68 0.71 0.62 0.53 0.60 0.61 0.49 0.40 0.44

CD 1.28 1.02 2.41 2.82 1.92 2.92 3.05 2.68 2.28 2.59 2.65 2.12 1.71 1.91

U0 = Urea supergranules Initial nitrogen content in soil = 175 kg ha-1

U1 = Polymer coated urea (single layer) N applied by fertilizer = 102 kg ha-1

U2 = Polymer coated urea (double layer) DAA = Days after application

U3 = Neem coated urea

U4= Sulphur coated urea

Fig. 4.1: Effect of different treatments on nitrogen content in soil at 3 days intervals

200

210

220

230

240

250

260

270

280

2 5 8 11 14 17 20 23 26 29 32 35 38 41

U0 (Urea supergranules) U1 PCU (single layer) U2 PCU (double layer)

U3 (Neem coated urea) U4 (Sulphur coated urea)

N c

on

ten

t in

so

il(k

g h

a-1)

Days after application

Table 4.2: Effect of different treatments on plant height

Treatments Plant height (cm)

30 DAT 60 DAT Harvesting

Urea supergranules (U0) 48.82 73.41 74.97

Polymer coated urea (single layer) U1 51.24 77.82 79.48

Polymer coated urea (double layer) U2 52.93 79.89 81.35

Neem coated urea (U3) 50.93 76.21 78.28

Sulphur coated urea (U4) 50.23 75.69 78.36

SEm± 0.34 0.34 0.26

CD (P=0.05) 1.45 1.45 1.10

Fig. 4.2: Effect of different treatments on plant height

0

10

20

30

40

50

60

70

80

90

U0 (Ureasupergranules)

U1 PCU (singlelayered)

U2 PCU (doublelayered)

U3 (Neemcoated urea)

U4 (Sulphurcoated urea)


Pla

nt

hei

ght

(cm

)

U0 (Urea U1 PCU (single U2 PCU (double U3 (Neem U4 (Sulphur supergranules) layer) layer) coated urea) coated urea)

Table 4.3: Effect of different treatments on number of tillers

Treatments Tillers hill-1







SEm± 0.23 0.22 0.32

CD (P=0.05) 0.98 0.94 1.39

Fig. 4.3: Effect of different treatments on number of tillers

0

5

10

15

20

25

U0 (Urea supergranules)






Tille

rs h

ill-1


Table 4.4: Effect of coated urea on number of leaves

Treatments Leaves hill-1







SEm± 0.72 0.95 0.60

CD (P=0.05) 3.11 4.12 2.60

Fig. 4.4: Effect of different treatments on chlorophyll content (SPAD)

0

5

10

15

20

25

30

35

40

45

50

U0 (Ureasupergranules)






Ch

loro

ph

yll c

on

ten

t (S

PA

D)


Table 4.5: Effect of different treatments on chlorophyll content (SPAD)

Treatments Chlorophyll content (SPAD)







SEm± 0.68 0.30 0.24

CD (P=0.05) NS 1.30 1.02

Fig. 4.5: Effect of different treatment on grain, straw, total biological yield

0

20

40

60

80

100

120

140

U0 (Urea supergranules)


U2 PCU(doublelayered)



grain yield straw yield Total biological yield

Yie

ld (

g h

ill-1

)


Table 4.6: Effect of different treatments on fresh and dry weight per hill at

harvest.

Treatments Fresh weight

(g hill-1)

Dry weight(g

hill-1)

Urea supergranules (U0) 121.21 93.89

Polymer coated urea (single layer) U1 143.96 112.90

Polymer coated urea (double layer) U2 157.50 124.32

Neem coated urea (U3) 138.36 105.21

Sulphur coated urea (U4) 133.32 102.71

SEm± 1.23 1.43

CD (P=0.05) 5.30 6.20

Table 4.7: Effect of different treatments on length and weight of panicle,

number of grain per panicle and test weight

Treatments

Panicle

length

(cm)

Weight

panicle-1 (g)

Grains

panicle-1

Test

weight

(g)

Urea supergranules (U0) 18.26 2.31 93.38 21.66

Polymer coated urea (single layer) U1 19.61 2.56 102.14 22.28

Polymer coated urea (double layer) U2 20.14 2.61 108.39 22.73

Neem coated urea (U3) 19.26 2.50 100.49 22.11

Sulphur coated urea (U4) 18.52 2.42 99.13 21.94

SEm± 0.22 0.02 0.75 0.20

CD (P=0.05) 0.93 0.07 3.23 NS

Table 4.8: Effect of different treatment on grain, straw, total biological yield and harvest

index

Treatments

Grain

yield

(g hill-1)

Straw

yield

(g hill-1)

Total

biological

yield (g hill-1)

Harvest

Index

(%)

Urea supergranules (U0) 39.43 54.46 93.89 42.00

Polymer coated urea (single layer) U1 48.85 64.04 112.90 43.25

Polymer coated urea (double layer) U2 54.39 69.93 124.32 43.75

Neem coated urea (U3) 45.16 60.06 105.21 42.92

Sulphur coated urea (U4) 43.60 59.11 102.71 42.41

SEm± 0.83 0.74 1.43 0.35

CD (P=0.05) 3.60 3.21 6.20 NS

Table 4.9: Effect of coated urea on nitrogen, phosphorus and potassium content in

grain

Treatments

Nutrient content in grain (%)

Nitrogen Phosphorus Potassium






SEm± 0.003 0.01 0.002

CD (P=0.05) 0.01 0.02 0.01

Table 4.10: Effect of coated urea on nitrogen, phosphorus and potassium

content in straw

Treatments

Nutrient content in straw (%)







SEm± 0.01 0.005 0.005

CD (P=0.05) 0.05 0.02 0.02

Table 4.11: Effect of different treatment on nutrient uptake by hill

Treatments Nutrient uptake (g hill-1)







SEm± 0.02 0.005 0.005

CD (P=0.05) 0.08 0.02 0.02

Table 4.12: Effect of coated urea on protein content in grain.

Treatments Protein content in grain (%)

Urea supergranules (U0) 6.70

Polymer coated urea (single layer) U1 7.00

Polymer coated urea (double layer) U2 7.03

Neem coated urea (U3) 6.84

Sulphur coated urea (U4) 6.83

SEm± 0.02

CD (P=0.05) 0.07

Chapter V

DISCUSSION

Rice (Oryza sativa L.) is the most important cereal crop of world both in

respect to area and production. India ranks first in area and second in production after

china in the world. The scope for increasing the production by cultivating more land,

particularly in developing countries like India is limited and hence, the other

alternative lies in increasing the production per unit area. To exploit the yield

potential of a variety, the inputs which can bring about a massive increase in

production are fertilizers and irrigation.

Among the various production inputs fertilizer nutrient is the most limiting

factor in agricultural land. By judicious use of these inputs, the same land can yield

many times more per hectare than is not only essential to maximize the production per

unit area and per unit time, but also to improve the productivity of every unit of other

costly inputs like water, labour, seed etc.

The present investigation entitled “Effect of polymer coated urea on plant

growth and yield of rice (Oryza sativa L.)” was conducted at the Agriculture

Research Farm, Institute of Agriculture Sciences, Banaras Hindu University, Varanasi

(U.P.) during the kharif season of 2014.

The findings of the experiment reported in the previous chapter have been

discussed and illustrated in this text with the help of suitable reasoning in the light of

literature available on the subject and principles of crop production.

5.1 Effect of weather on crop

Results of field investigations are affected by weather conditions. The effect of

weather during the crop season is one of the most important factors which determine

the extent of crop growth, development and overall performance. Every crop has its

own cardinal temperature, humidity, rainfall, sunshine duration and other weather

condition for higher yields. But, these optimal conditions seldom prevail. A slight

alteration in weather condition may adversely affect overall growth and development.

Discussion

~48~

Rice is basically a crop of warm regions of the tropics and sub tropics.

Summerfield et al. (1974) showed that temperature during cropping season have

significant influence on vegetative and reproductive phases. The mean maximum

temperature ranging from 23.60C to 43.40C and minimum temperature between

24.20C to 28.70C during the cropping period provide average condition for crop

growth.

The meteorological data (Table 3.1 and depicted in Fig. 3.1) during the course

of experimentation showed that in general weather conditions were congenial for

normal growth of rice crops.

5.2 Effect of weather on polymer coated urea (PCU)

The soil N analyses at 3 days interval after the deep placement of coated urea

envisage that N released from coated urea was influenced by weather elements

specially temperature and soil moisture content.

There was no marked difference in temperature during the experimentation

and therefore no fluctuation was noticed in release rate of nitrogen with respect to

temperature, but slight decline was noticed during 21-26 days after application (DAA)

due to decrease in temperature; after which sharp increase in N content of soil and

release rate found in the observations taken at 26, 29, 32 and 35 DAA due to higher

soil temperature in respective week. Wang et al. (2011) reported that at 250C lower

temperature small portion of N released from coated particle as compared to higher

temperature 1000 C when 100 % N release within some hours.

Moisture is another factor that affects the rate, pattern and duration of release

of nitrogen from coated urea (Fujinuma et al., 2009; Shaviv, 2005). However, since

the trail was conducted under irrigated condition, the effect of moisture remained

neutral for all the treatments.

5.3 Effect of polymer coated urea (PCU) on crop growth

Crop growth is the product of interaction of environmental factors, genetic

constituents and agronomic measures for providing suitable environmental condition

to ensure optimum plant growth.

Discussion

~49~

Nitrogen is a component of many important organic compounds ranging

from protein to nucleic acids. It is an integral part of chlorophyll, which is the primary

absorber of light energy needed for photosynthesis. Plant growth is adversely affected

due to deficiency of nitrogen as it is a constituent of proteins, chlorophyll and

vitamins. Deficiency of N causes stunted growth, chlorosis of lower leaves and less

tillering in cereals.

Results of experiment showed that polymer coated urea had significant effect

on plant growth and yield (Table 4.2-4.8). Better growth and higher grain and straw

yield were obtained in polymer coated urea compared to urea supergranules. Plant

height, tiller number, dry matter production, grains per panicle and grain yield

increased by use of polymer coated urea over uncoated urea i.e. 8.51%, 24.33%,

32.41%, 16.07% and 23-37% respectively. Nutrient uptake by plant and N recovery

was noticed higher with coated urea compared to uncoated urea. The reason behind

this was the slow release pattern of nitrogen from PCU (polymer coated urea) which

synchronized with N release to plant nutrient demand for better plant growth and crop

yield by reducing nitrogen losses and environmental pollution (Kanno, 2008).

5.3.1 Growth characters

Growth parameters which include plant height, number of tillers per plant and

dry matter accumulation were significantly influenced by different sources of N. In

the investigation, it was observed that polymer coated urea caused significant effect

on all the growth parameters viz. plant height, tiller production, leaf number and dry

matter accumulation at all the growth stages (Table 4.2-4.6).

Maximum plant height was recorded with application of double layer polymer

coated urea, which was at par with single polymer coated urea (U1) at 30 DAS &

harvest. It was significantly superior to rest of treatments. Similar results were

recorded by Nash et al. (2013); Pinpeangchan and Wanapu (2015). Nitrogen released

from polymer coated urea granules matching to plant nutrient demand improved plant

height and induce better plant growth.

The number of tillers were found maximum in deep-placed polymer coated

urea (double layer), which remained at par with PCU (single layer). The increase in

Discussion

~50~

number of tillers under PCU (double layer) was observed because of increasing

availability of nitrogen till the maturity of crop.

Polymer coated urea controls the release of N from coated particles and

delays the availability of nitrogen to the crop and continuously produces number of

green leaves upto maturity. Higher number of green leaves and maximum chlorophyll

content were observed with polymer coated urea (double layer) at the later stages of

crop growth. Hatfield and Parkin (2014) observed increased greenness as well as

duration of green leaf area in the corn crop upto grain-filling stage with the use of

fertilizers like PCU, stabilized fertilizers and nitrification inhibitors.

Dry matter production differed significantly due to different sources of N at

all the growth stages. Polymer coated urea (double layer) was significantly superior to

rest of treatments, whereas neem coated urea was found statistically at par with

sulphur coated urea at harvest. Lowest dry matter production was recorded with

uncoated urea (urea supergranule). Several researchers (Singh et al., 2004; Pack et al.,

2007; Sahota et al., 2010) also reported marked increase in dry matter accumulation

with polymer coated urea in different crops.

Increase in plant height, tillers per plant, leaf greenness, leaf weight, LAI and

plant dry weight with the application of PCU was also reported by Nash et al. (2013);

Strey and Christians (2013); Hatfield and Parkin (2014).

5.3.2 Yield attributes

Yield attributes, which determine yield, is the resultant effect of the

vegetative development of the plant. All the attributes of yield including effective

tillers per hill, panicle length, panicle weight, grain panicle-1 were significantly

influenced by sources of N (Table 4.7).

All the coated urea treatments significantly influenced the yield attributes as

compared to uncoated control. Maximum number of effective tillers was counted in

deep placed polymer coated urea (double layer) due to availability of N for longer

period of time. About 14-24% increase in number of panicle was noticed with

polymer coated urea at harvest. The number of effective tillers per hill was increased

Discussion

~51~

because of increase in availability of N to the crop during tillering to reproductive

stage.

With the application of PCU (double layer) higher panicle length and weight,

grains per panicle and test weight were recorded. The result indicated that increase in

yield contributing characters of plants treated with PCU was due to availability of

adequate amount of N during reproductive and grain filling stages. Significant

increase in number of grains per panicle in PCU over conventional urea was also

reported by Patil et al. (2010). Singh et al. (2004) also found similar results with the

use of polyolefin resin coating slow release Fe fertilizers.

5.3.3 Yield

Yield is the result of coordinated interplay of various growth characters

(Ramamoorthy et al., 1998). Grain and straw yield in terms of g hill-1 were

significantly influenced by different coated urea fertilizers (Table 4.8). The treatments

with higher yield attributing characters produced higher grain and straw yields.

Polymer coated urea fertilizers (both single layer and double layer) showed

greater efficacy in increasing the grain and straw yield in comparison to other

treatments. However all coated urea had significant effect in increasing grain and

straw yields due to availability of nitrogen in adequate amount for longer duration.

Ma et al. (2012) also reported 10.4-16.5% increase in grain yield with sulphur and

polymer coated urea over traditional urea.

The grain and straw yields in term of q ha-1 were found to be the highest

(24.17 and 31.08 q ha-1 respectively) under polymer coated urea (double layer) as

compared to urea supergranules with 17.52 and 24.02 q ha-1. Carreres et al. (2003),

Slaton et al. (2009) and Golden et al. (2009) observed significant increase in grain

yield with PCU than conventional urea. The results of experiments conducted on

potato revealed an increase in tuber yield with PCU over control/conventional N

fertilizers like urea, ammonium sulfate [AS] & ammonium nitrate [AN] (Zvomuya

et al., 2003 and Pack et al., 2007).

Discussion

~52~

5.3.4 Nutrient uptake by plant

In general N content in plant tissue ranges from 1-4% with average 1.5%

total nutrient content. Nitrogen is an essential nutrient which directly affects plant

growth and plant nutrient uptake. The nitrogen uptake by plant and its accumulation

in grain and straw are therefore affected by availability of N in later growth stage

(Carreres et al., 2003).

The nutrient uptake (N, P and K) by plant (grain and straw) varied

significantly with the application of different sources of N (Table 4.9-4.11). Highest

N, P and K content in grain as well as maximum nutrient uptake by plant was

recorded in polymer coated urea (double layer), while neem coated urea remained at

par with sulphur coated urea. The maximum uptake of nitrogen by the plants is

induced by synchronized release of nitrogen from coated urea (Kaneta et al., 1994).

PCU application in saturated paddy field enhances fertilizer use efficiency,

NUE as well as nitrogen recovery percentage by ensuring better uptake and

translocation of nitrogen released from polymer coated urea (Kanno et al., 2000;

Kanno, 2008). Higher nitrogen use efficiency in PCU may be related to release of N

in the soil-plant system according to plant demand and consequently higher

utilization. Fageria (2011) reported 25% higher NUE at polymer coated urea

compared to conventional urea.

Reviews related to PCU fertilizers confirm it as best fertilizer in lowland

paddy. PCU (32% and 40% N) and isobutylidenediurea (IBDU) application shortly

before flooding improved total N uptake and recovery efficiency compared to the

conventional fertilizer application (Carreres et al., 2003).

5.3.5 Protein content

N is an important component for most of the amino acids (Swan, 1971a).

The protein content of grain is therefore affected by availability of nitrogen during

grain formation. The quality of grain like protein and starch are also affected by

polymer coated urea. Greater protein content of grain obtained from the application of

polymer coated urea (Farmaha and Sims, 2013).

Discussion

~53~

The result of the research on protein content of grain (Table 4.12) showed that

higher % of protein could be obtained by polymer coated urea (both single and double

layer). Minimum protein content noticed in urea supergranules, was perhaps due to

unavailability of N during grain formation and grain-filling period. Ma et al. (2012)

also reported 5.8-18.9% and 0.3-1.4% increase in protein and starch content of grain

in wheat with the application of polymer coated urea over traditional urea.

Chapter VI

SUMMARY AND CONCLUSION

In this chapter an attempt has been made to summarize the results and draw a

valid conclusion based on the significant findings of the present investigation entitled

“Effect of polymer coated urea on the growth and yield of rice (Oryza sativa L.)”.

The investigation was conducted during the Kharif season of 2014 at Research Farm,

Institute of Agricultural Sciences, Banaras Hindu University, Varanasi, Uttar Pradesh

(India) with the following objectives:

1. To find out N content in soil at 3 days interval upto 41 days after application

with deep placement of different coated urea like polymer coated urea, neem

coated urea, sulphur coated urea and urea supergranules.

2. To find out their effect on plant growth, yield and nutrient uptake by rice.

To fulfill the above objectives, field experiment was laid out in randomized

complete block design (RCBD) with five treatments replicated four times. Paddy

variety NDR-97 was grown as test crop by adopting a spacing of 15×15 cm2. The soil

of the experimental field was Gangetic alluvial and sandy clay loam in texture with

pH 7.4, 0.38% organic carbon, 175 kg, 18 kg and 199.6 kg ha-1 of available nitrogen,

phosphorus and potassium respectively. A uniform fertilizer dose of 102-60-60 kg N,

P2O5, K2O ha-1 was applied by basal application and deep placement of 2g coated urea

a week after transplanting.

Observations were recorded on N content of soil at 3 days interval after deep

placement and on crop attributes viz. plant height, tiller number, functional leaves,

chlorophyll content, yield attributes of rice and yield and nutrient content and uptake

by crop.

The salient results of the present study are summarized below:

The negligible or small change in soil N content just after application of

polymer coated urea was noticed. However, N content in soil (rate of release)

Summary and Conclusion

~55~

gradually increased with the passage of time and the most delayed release was

found with polymer coated urea.

The growth parameters viz. plant height, number of tillers hill-1 and dry matter

accumulation of rice were maximum with the deep placed PCU (double layer).

Higher chlorophyll content was observed with polymer coated urea than other

treatments at all the stages of growth.

Significantly improved yield attributes like number of panicles per hill, weight

of panicle, grains per panicle and test weight were found with double layer

polymer coated urea compare to uncoated urea granule.

Grain, straw and total biological yield were found maximum with polymer

coated urea (double layer).

The maximum uptake of N, P and K by crop was recorded with PCU (double

layer) followed by PCU (single layer) and minimum with urea supergranules.

CONCLUSION

On the basis of results summarized above, it can be concluded that the release

rate of nitrogen and soil nitrogen content gradually increased upto 41 days with the

application of polymer coated urea. It also has significant effect on growth,

development and production on rice crop under puddled condition.

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