1
BINA/Ag. Engg.Division-8
A Research Report
on
Evaluation of Different Water Management Practices for
Water Savings, Nitrate Leaching and Rice Yield
By
Dr. Md. Asgar Ali Sarkar (Chief Scientific Officer and Head)
Dr. M. H. Ali * (Senior Scientific Officer)
Agricultural Engineering Division
Bangladesh Institute of Nuclear Agriculture BAU Campus, Mymensingh 2202
Bangladesh
*Corresponding Author, Email: [email protected], [email protected]
March 2010
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Preface
Over the past few decades there has been increased attention to nitrate concentration
in ground water, particularly to leaching associated with agricultural activities. Concerns
grow about subsurface water quality due to advective downward transport of pollutants as
more water moves through the soil profile. Application of excess nutrient fertilizers for crop
production may directly affect subsurface water quality especially for NO3-N, which is highly
mobile.
In Bangladesh, nitrate in groundwater is associated with irrigated rice-based cropping
systems. Rice is generally grown under ponded water. The combination of high N-fertilizer
input culture along with ponded water may lead to increased risk of nitrate leaching.
Considering this point, the reported investigation was carried out. The research results will
help in adopting appropriate water management strategy for water saving, increased rice yield
and specifically for reducing risk of NO3-N leaching responsible for groundwater pollution.
The investigators
3
Summary
Contamination of groundwater with nitrate is attributed to deep percolation of water
containing the chemical. Thus, proper irrigation scheduling can reduce deep percolation and resulting
nitrate loss to a certain extent. Long-term (2000-2005) field and lysimetric study were conducted to
evaluate different water management practices for saving the costly irrigation inputs, maximizing the
rice yield and conversely minimizing the leaching of nitrate-nitrogen (NO3-N) below the root zone.
The study was carried out with recommended N-fertilizer rate for the study area and different
irrigation strategies. The irrigation strategies were: Continuous ponding of 3-5 cm [T1]; continuous
saturation [T2]; alternate flooding (5 cm) and drying to 3, 5 and 7 days after the disappearance of the
ponded water, thereby referred to as T3, T4, and T5, respectively. The water samples were collected
from the outlet pipe provided at the bottom of lysimeter and by ceramic suction cups installed in the
treatment plots in the field, which were then analyzed in the laboratory for NO3-N concentration. The
results showed that the variation in yield among the treatments were small and statistically
insignificant. But irrigation water required in alternate wetting and drying methods (T3 to T5) were 44
to 54 % less than that of continuous ponding and 23 to 36 % less than that of saturation method (T2).
The pattern of NO3-N concentration and the total NO3-N loss varied among treatments both at field
and lysimeter. Nitrate leaching during crop growing period in lysimeter ranged from 1.5 to 3.5 kg/ha.
The cumulative NO3-N concentration data showed that the total NO3-N loss were higher in continuous
ponding and continuous saturation under field condition. Considering the nitrate loss, rice yield and
water saving, the alternate flooding and drying 5 to 7 days after disappearance of ponded water
seemed to be the best strategy for rice cultivation.
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Table of Contents
Content Page
Title page ....................................... 1
Preface .......................................2
Summary .................................... 3
Table of contents .................................... 4
List of Tables .................................... 5
List of Figures .................................... 5
1 Introduction .................................... 5
2 Material and Methods .................................... 8
2.1 Experimental site, soil and climate ....................................
2.2 Irrigation treatments ....................................
2.3 Experimental plots and culture ....................................
2.3.1 Lysimeter ................................................
2.3.2 Field ................................................
2.3.3 Fertilizer and other cultural practices .........................................
2.4 Drainage collection, water sampling ................................................
2.5 Water balance ................................................
2.6 Water analysis for nitrate .................................................
2.7 Yield data recording .................................................
2.7 Statistical analysis .......................................................
3. Results and Discussion .................................... 12
3.1 Rainfall amount during crop period ....................................
3.2 yield, water use and water productivity ...................................
3.3 NO3 –N leaching ....................................
3.3.1 Drainage water ....................................
3.3.2 NO3 –N concentration in soil profile .............................
3.4 Conclusion .................................
References .............................. 17
5
List of Tables
Table No. Page No.
Table 1. Yield, irrigation requirement and total water use of rice in field under different
treatments .............
Table 2. Average yield and water productivity of rice in field under different treatments
……….
Table 3. Average yield and water productivity of rice in lysimeter under different treatments
……….18
Table 4. Average estimated amount of NO3-N leaching under different treatments in
lysimeter & field ................
List of Figures Fig. No. Page no.
Fig.1. Rainfall distribution during the crop growing period .................................... 19
Fig. 2(a). NO3-N concentration of drainage water during the crop growing season (Field
and lysimeter) during 2000 .............................................
Fig.2(b). NO3-N concentration of drainage water during the crop growing season (Field
and lysimeter) during 2001 ......................................
Fig.2(c) NO3-N concentration of drainage water during the crop growing season (Field
and lysimeter) during 2002 ......................................
Fig.2(d) NO3-N concentration of drainage water during the crop growing season (Field
and lysimeter) during 2003 .....................................
Fig.2(e) NO3-N concentration of drainage water during the crop growing season (Field
6
and lysimeter) during 2004 .....................................................
Fig.2(f) NO3-N concentration of drainage water during the crop growing season (Field
and lysimeter) during 2005 .............................................
Fig. 3(a). NO3-N concentration of soil sample (Field and lysimeter) during 2000 ..........
Fig.3(b). NO3-N concentration of soil during the crop growing season (Field
and lysimeter) during 2001 ..................................................
Fig.4. Average NO3-N concentration of drainage water collected from the field …..
Fig.5. Average cumulative NO3-N concentration of field and lysimeter soil at harvest ….29
Evaluation of Different Water Management Practices for Water
Savings, Nitrate Leaching and Rice Yield
1 Introduction Modern agriculture is changing its traditional priorities and practices by developing
and adopting new techniques or methods, intending to increase farming production and
maintain soil fertility. The farmers use water to irrigate and chemical fertilizers to increase
soil fertility and production. Under ideal conditions, only the amount of fertilizer that can be
used by the plant would be applied, leaving no residual to move below the root zone.
However, in most cases, not all of the applied nitrogen is assimilated by the plants, allowing
some to move below the root zone. Nitrogen in the soil that is not returned to the atmosphere
in the form of nitrogen gas or ammonia is generally converted to the nitrate form by bacteria.
Nitrate is very mobile, and if there is sufficient water in the soil, it can move readily through
the soil profile.
Addition of water and nitrogenous fertilizer are highly effective means to improve
crop yield. There is a direct relationship between large NO3-N losses, excess N inputs and
inefficient irrigation management (Santos et al., 1997). Extensively and specifically,
intensively cropped areas are sources of ground water contamination. Contamination of
ground water by agricultural chemicals is a major concern throughout the world. Nitrate
contamination is a particular concern for both health and environmental quality. Ground
water is the major source of drinking for both urban and rural people of Bangladesh as well
7
as many parts of the world. Nitrate may cause methemoglobinemia (blue baby syndrom) in
infants (Stone et al., 1997) when it is above the maximum concentration level of 10 mg/l.
Additionally, nitrate interaction with other dietary substances may cause health problems in
human (Maidson and Brunett, 1985).
A large number of research articles found in the literature deals with the problem of
nitrate leaching under different conditions of soils, crops and cultural practices. Most of them
are from studies conducted in crops grown under unsaturated or non-ponded condition
(Moreno et al., 1999; Yets et al., 1992; Ferguson et al., 1991; Casey et al., 2002; Roth and
Fox, 1990). But in irrigated rice cultivation, water is ponded in the field during the whole
growing period. Under such conditions, the leaching of nitrate (amount and patterns) in
agricultural soils can be different from that occurred from dry-land crops. Bawatharnai et al.
(2004) showed that higher rates of irrigation push down the diluted nitrate solution rapidly.
About 50% of the world’s rice area is irrigated by ponding of the field, and produces
75% of the world’s rice production (Tabuchi and Hasegawa, 1995). A high production is
attained by high inputs (water, fertilizer, pesticide, etc.). Among the various factors
contributing to increased rice production, irrigation has the highest effect followed by
fertilizer and variety. Sustainable paddy production depends on the sustainable use of water
resources including the technology that makes minimum use of agricultural chemicals.
In Bangladesh, nitrate in the ground water is a concern in irrigated rice-based
cropping systems. Rice is generally grown under ponded water. The combination of high N-
fertilizer input culture along with ponded water may lead to increase risk of nitrate leaching.
The objective of this study was to minimize nitrate leaching by effective management of
irrigation water in irrigated Boro rice cultivation.
2 Materials and Methods
2.1 Experimental site, soil and climate
The experiments were conducted at the experimental farm of the Bangladesh Institute of
Nuclear Agriculture (BINA), Mymensingh, Bangladesh (Latitude 240 43' N, longitude 900 26'
E, and 7.2 m above mean sea level), during 2000-2005. The local climate is humid and sub-
tropic with summer dominant rainfall. The average annual rainfall at the site (1991-2004) was
about 2260 mm, mostly concentrated over the months of April to September. The texture of
the experimental soil is silty loam.
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2.2 Water management strategies / Irrigation treatments
Water management practices followed were:
T1 = Continuous ponding (3-5 cm)
T2 = Continuous saturation
T3 = Alternate flooding (5 cm) and drying for 3-days after disappearance of the ponded
water
T4 = Alternate flooding (5 cm) and drying for 5-days after disappearance of the ponded
water and
T5 = Alternate flooding (5 cm) and drying for 7 days after disappearance of the ponded
water
2.3 Experimental setup and cultural practices
The experiment was set up in field and lysimeter simultaneously. In both cases the
treatments and cultural practices were same but different only in crop environment. In field,
the crop was grown under normal and natural condition having no three-dimensional barrier
of water and solute flow. In contrast, crops grown in control condition in lysimeter having
barrier of the lysimeter walls for horizontal movement of water and solute. Moreover, in
micro-level experimental environment, the crops have climatic and nutrient receiving
competition, and error factor for heat reflection due to lysimeter’s visible surface walls
compared to the field condition. Some features of both experimental conditions are described
below.
2.3.1 Lysimeter
Each lysimeter tank (drainage type) has a surface area of 2m2 (2m x 1m) with soil
depth of 1.5m. The investigation was carried out in 5 tanks, one for each treatment. Each tank
has separate arrangements for irrigation, drainage and soil water measurements. Hassan et al.
(1995) provided a detailed description of the construction of the lysimeter.
2.3.2 Field
In the field, the experimental design was RCBD with four replications. The unit plot
size was 5m x 4m. Line to line and plant to plant distances within the line were maintained
as 20cm and 15cm, respectively.
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2.3.3 Fertilizer and other cultural practices
The experiment was fertilized with the recommended doses of urea @ 215 kg/ha, TSP
@ 180 kg/ha and MP @ 100 kg/ha. Seedling of 35~40 days old was transplanted on mid
January every year and the crop was harvested on third week of May. All but urea fertilizer
were applied at transplanting time. The urea was applied as top dressing in three equal splits
at 7, 39 and 64 days after transplantation. Weeding was done as per need. Insecticide was
sprayed at the pre-flowering and the grain formation stages. Soil samples from each treatment
plot for both the field and lysimeter were also collected up to 90 cm depth at land preparation
and at harvest to determine the NO3-N content in profile.
2.4 Drainage water collection and water sampling
Vacuum gauge water samplers (85 cm deep) were installed in all the treatment plots in
one replication. Moreover, 38cm depth water samplers were installed in T1, T2, T3 and T5
treatment plots and 120cm water samplers were installed in only T1, T4 and T5 treatment plots
in one replication. Water samples were collected after the normal accumulation of water into
the sampler through the ceramic cup. Whenever normal accumulation was insufficient, each
sampler was sucked for 20-30 minutes by a hand suction pump (having vacuum gauge) and
then the accumulated water was collected. The water samples were then analyzed into the
laboratory for NO3-N concentration. From the lysimeter plots, drainage water was collected
by opening the bottom drainage outlet pipe situated at 120cm below the soil surface.
In case of lysimeter, the NO3-N leached below the root zone (at 1.2m depth) for each
sampling was calculated using the following formula:
LN = V x Cd ..........................................(1)
Where,
LN = amount of NO3-N (mg) leached below the root zone
V = volume of water leached below the root zone (Litre)
Cd = concentration of NO3-N (mg/L) of the drainage water collected below the root
zone.
Total NO3-N leached during the growing season was calculated by summing up LN for each
sampling and expressed as amount per unit area (Kg/ha).
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2.5 Water balance
The general water balance equation at plot level in paddy field can be written as:
P + I = ET + R + D .............................................. (2)
where, P is precipitation (cm), I is irrigation water (cm), ET is evapo-transpiration (cm), R is
surface runoff (cm) and D is deep percolation. The sum of the terms in the left hand and right
hand side of the equation are water gain and water loss, respectively. Simplifying the
equation for ET becomes:
ET = I + (P – R) – D
or ,
ET = I + Peffective – D ................................(3)
where, Peffective is effective rainfall which was calculated following the method outlined by
Dastane (1974). Any amount above 75 mm/day and rainfall in excess of 125 mm in 10 days
was treated as non-effective. In case of deep percolation, it was taken as 2 mm/day (equal to
saturated hydraulic conductivity) for the whole growing period for ponding and saturated
treatments, and one-third of the growing days with the same rate for the other treatments. For
lysimeter, excess water was collected from the drainage outlet pipe provided at the bottom of
each tank and the cumulative amount was considered as the total deep percolation for each
treatments.
2.6 Water analysis for NO3-N
The collected samples were analyzed in laboratory for NO3-N concentration following
the method of Rand et al. (1976).
2.7 Yield data recording
Agronomic data and yield parameters were recorded in time. The yield of the whole
unit plot was collected and then converted to Kg/ha.
2.8 Statistical analysis
The yield data was analyzed following analysis of variance technique using MSTATC
statistical package. The means were separated using ‘Least Significant Difference’ test at 5
% significance level.
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3 Results and Discussion
3.1 Rainfall amount during the crop period
The amount and distribution of rainfall during the rice growing period (transplanting to
harvest) are showed graphically in Fig. 1. The amount of rainfall up to 90 days from
transplanting (starting of grain formation) in all the years are low, thus, there were no
problem to maintain the scheduled irrigation treatments.
3.2 Yield, water use and water productivity
Field
Yield and components of water use of rice under different irrigation management
practices are presented in Table 1. The irrigation treatments showed insignificant difference
in yield. Pattern of yield variation among the treatments varied among years. The average
yield, ET, water productivity (WP) and irrigation water productivity (IWP) are summarized
in Table 2. On an average, the treatment T2 produced the highest yield followed by T5
(Table 1). But the variations in yield among the treatments are small.
The alternate drying and re-watering ( in treatments T3 and T5) may have contributed
to physio-biochemical changes and adjustment, which made the plants less sensitive to water
stress, thus less adverse impact on yield. The results are comparable with the recent findings
(Liang et al. 2002 ). Liang et al. (2002) demonstrated that alternate drying and re-watering
had a significant compensatory effect that could reduce transpiration. Turner (1986) reported
that plants can adapt to slowly developing water deficit so that the water potential at which
physiological activity is affected is changed. It was also reported that osmotic adjustment
allows for the maintenance of photosynthesis and growth by stomatal adjustment and
photosynthetic adjustment (Turner, 2004).
Another aspect is that monocarpic plants such as wheat and rice need the initiation of
whole plant senescence so that stored carbohydrates in stems and leaf sheaths can be
remobilized and transferred to their grains. Delayed whole plant senescence lead to poorly
filled grains and unused carbohydrate in straws (Zhang and Yang, 2004). Slow grain filling
may often be associated with delayed whole plant senescence. Zhang and Yang (2004)
showed that the early senescence induced by water deficit does not necessarily reduce grain
yield even when plants are grown under normal nitrogen (N) condition. The gain from
accelerated grain-filling rate and improved translocation outweighed the possible loss of
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photosynthesis as a result of shortened grain filling period when subjected to water stress
during grain filling.
On an average, the treatment T1 consumed highest amount of irrigation water (128
cm) followed by T2 (89 cm), but the yield difference is only 0.28 t/ha. The treatment T3 saved
20 cm of irrigation water compared to T2 accompanied by a yield reduction of 0.31 t/ha.
Similarly, the treatment T5 saved 32 cm water with a yield reduction of only 0.25 t/ha.
As the yield difference is small, water productivity and productivity of irrigation
water are of reversed trend of water use, i.e. the highest with the lowest irrigation water (T5)
and the lowest with the highest irrigation water (T1).
Lysimeter
The average yield, water use and water productivity for the lysimeter grown rice are
presented in Table 3. It is observed that yield in lysimeter is higher than that of the field. This
may be due to less competition of micro-climatic in the lysimeter crops, specially the
sunlight. Alike field, here also, yield varied among treatments by narrow range. Here, the
treatment T4 produced the highest yield. The irrigation water consumed followed the similar
trend as that of the field.
3.3 NO3-N leaching
3.3.1 Drainage water
The concentration of NO3-N in the drainage water under different treatments are
shown in Fig. 2(a) to Fig. 2(f). The fertilizer N were applied at 7, 39 and 64 days after
transplanting (DAT). Leaching of NO3-N in general increased not immediately after the
application of fertilizer, but lagging few days (Fig. 2(a)). The pattern of NO3-N concentration
and thus the NO3-N loss varied among treatments, and also among field and lysimeter.
During the crop period in 2000, the NO3-N concentration in the field at later stage (75 DAT)
were higher in T3, and T4. The cumulative NO3-N concentration data (Fig. 2(b)) to Fig. 2(e))
showed that in most cases the total NO3-N loss were higher in T1 and T2 under field condition
and in T4 and T5 under lysimeter. The higher value under stressed condition in lysimeter may
be due to the higher inflow rate of water through the passage in between lysimeter wall and
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soil. The total amount of NO3-N loss under lysimetric condition varied between 1.09 to 2.0
kg/ha (Table 4), having an average of 1.55 kg/ha.
From the field data, it was observed that there was a reduction in nitrate leaching
under the irrigation strategy in which irrigation water was applied at 3 to 7 days after
disappearance of ponded water (treatment T3 to T5), without insignificant reduction in rice
yield. Other studies (Skopp et al., 1990; Doran, 1980) have demonstrated that the increased
soil-water increased mineralization rates, exposing more nitrate to leaching. Lower
mineralization in lysimeter may occur due to a decrease in organic matter (Casey et al.,
2002). Unfortunately, a record of soil organic-matter content at various stages of the study
was not kept to verify whether mineralization rates were increasing or decreasing.
3.3.2 NO3-N concentration in soil profile
The NO3-N concentration at various depths at sowing and harvest under different
treatments are shown in Fig. 3(a) and Fig. 3(b). The NO3-N concentration showed fluctuating
pattern at different depths and also varied among treatments. During the year 2000 (Fig.
3(a)), the NO3-N concentration in field soil at harvest was higher than the sowing time and
showed gradually higher trend in the more irrigated plots than the water stressed plots.
Moreover, it was found that the maximum NO3-N concentration was at 90 - 120 cm soil
depth in T1. On the other hand, in lysimeter, the highest NO3-N was found at 0 - 30 cm depths
in T1.
The cumulative NO3-N concentration increased gradually in lysimeter in the deeper
soil profiles (Fig. 3(b)). Moreover, higher concentration trend was also observed in the water
stressed plots (T3, T4). This may be attributed by the interspaces in between soil and lysimeter
wall. But in the field, NO3-N showed a gradually higher downward trend in deeper soil layers
in the more irrigated plots than the water stressed plots. It indicated that the irrigated plots
with ponded water allowed the free downward movement of NO3-N causing its higher
leaching rate. The average (over years) cumulative NO3-N of water and soil are presented in
Fig.4 and Fig.5, respectively.
From the field data, it revealed that there was a reduction in nitrate leaching under the
irrigation strategy in which irrigation water was applied at 3 to 7 days after disappearance of
ponded water (treatment T3 to T7), without insignificant reduction in rice yield.
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3.4 Conclusion
Considering the nitrate loss, rice yield and water saving, the alternate flooding and drying for
5 to 7 days after disappearance of ponded water seemed to be the best strategy for rice
cultivation.
References
Casey, F.X.M., N. Derby, R.E. Knighton, D.D. Steele, and E.C. Stegman (2002). Initiation
of irrigation effects on temporal nitrate leahing. Vadose Zone J. 1, 300-309.
Dastane, N.G. (1974). Effective rainfall in irrigation agriculture. FAO Irrigation and Drainage
Paper 25, FAO, Rome, p. 61
Doran, J.W. (1980). Soil microbial and biochemical changes associated with reduced tillage.
Soil Sci. Soc. Am. J. 44, 765-771.
Ferguson, R. B., C. A. Shapiro, G. W. Hergert, W. L. Kranz, N. L. Klocke and D. H. Krull
(1991). Nitrogen and irrigation management practices to minimize nitrate leaching
from irrigated corn. J. Prod. Agric. 4: 186-192.
Hassan, A. A., A. A. Sarkar and A. H. Sarder (1995). Design and construction of non-
weighing gravity type lysimeter for agro-hydrological studies. Lysimeter report-
BINA / Ag. Engg/4, 1995.
Liang, Z.S., F.S. Zhangand J.H. Zhang (2002). The relations of stomatal conductance, water
consumption, growth rate to leaf water potential during soil drying and rewatering
cycle of wheat. Botanical Bulletin of Academia Sinica, 43: 187 – 192
Maidson, R.J. and J.O. Brunett (1985). Overview of the occurrence of nitrate in groundwater
of the United States. U.S. Geol. Surv. Water Supply Pap. 2275.
Moreno, F., J. A. Cayuela, J. E. Fernandez, E. Fernandezboy, J. M. Murillo and F. Cabrera
(1999). Water balance and nitrate leaching in on irrigated maize crop in SW spain.
In: Kirda, et al. (edit.) Crop Response to Deficit Irrigation.
15
Rand, M. C., A. E. Greenberg, and M. J. Taras (1976). Standard Methods for the
examination of Water and Wastewater. Published by American Public Health
Association. pp. 189-205
Rashid, M.A., A.F.M. Saleh, and L.R. Khan (2005). Water savings and economics of
alternate wetting and drying irrigation for rice. Bangladesh J. Water Resour. Res.
20: 81-93.
Ritter, W. F. (1989). Nitrate leaching under irrigation in the united states – a review. J. Env.
Sci. and Health. Part-A: Env. Sci. and Engg., A24: 4, 349-378
Roth, L. V. and R. H. Fox (1990). Soil nitrate accumulations following nitrogen-fertilized
corn in Pennsylvania, J. Environ. Qual., 19: 243-248.
Santos, D.V., P.L. Sousa, and R.E. Smith (1997). Model simulation of water and nitrate
movement in a level-basin under fertigation treatments. Agric. Water Manage., 32:
293-306
Sarkar, A. A., A. A. Hassan, M. H. Ali and N. N. Karim (2002). Supplemental irrigation for
Binashail rice cultivation at two agro-ecological zones of Bangladesh. Bangladesh J.
of Agril. Sci., 29(1): 95-100
Skoop, J., M.D. Jawson, and J.W. Doran, (1990). Steady-state microbial activity as a function
of soil water content. Soil Sci. Soc. Am. J. 54, 1619-1625
Stone, K.C., P.G. Hunt, M.H. Johnson, and T.A. Matheny (1997). Groundwater nitrate-N
concentrations on an eastern coastal plans watershed. Paper presented in an ASAE
meeting on Aug.10-14, 19997, Paper No. 97-2152, 560 Niles Road, St. Joseph, MI
49085-9659, USA.
Tabuchi, T. and S. Hasegawa (edit.)(1995). Paddy field in the world. Japanese Society of
Irrigation, Drainage and Reclamation Engineering, Tokyo, 353p.
Turner, N. C. (1986). Adaptation to water deficits: a changing perspective. Aust. J. Plant
Physiol., 13: 175-190
Turner, N.C. (2004). Sustainable production of crops and pastures under drought in a
Mediterranean environment. Annals of Applied Biology, 144: 139-147
Yates, M. V., D. E. Stottlemyer, and J. L. Meyer 1992. Irrigation and fertilizer management
to minimize nitrate leaching in Avocado production. Proc. of Second World
Avocado Congress, pp. 331-335.
Zhang, J. and J. Yang (2004). Improving harvest index is an effective way to increase crop
water use efficiency. In: Proc., 4th Int. Crop Sci. Congress, held at Brisbane, Sept.
2004, on the theme “Crop Science for Diversified Planet”.
16
Moreno, F., J. A. Cayuela, J. E. Fernandez, E. Fernandezboy, J. M. Murillo and F. Cabrera
(1999). Water balance and nitrate leaching in on irrigated maize crop in SW spain.
In: Kirda, et al. (edit.) Crop Response to Deficit Irrigation.
Yates, M. V., D. E. Stottlemyer, and J. L. Meyer (1992). Irrigation and fertilizer management
to minimize nitrate leaching in Avocado production. Proc. of Second World
Avocado Congress, pp. 331-335.
Ferguson, R. B., C. A. Shapiro, G. W. Hergert, W. L. Kranz, N. L. Klocke and D. H. Krull
(1991). Nitrogen and irrigation management practices to minimize nitrate leaching
from irrigated corn. J. Prod. Agric. 4: 186-192.
Casey, F. X. M., N. Derby, R. E. Knighton, D. D. Steele and E. C. Stegman (2002). Initiation
of irrigation effects on temporal nitrite leaching. Vadose Zone Journal, 1: 300-309.
Roth, L. V. and R. H. Fox (1990). Soil nitrate accumulations following nitrogen-fertilized
corn in Pennsylvania, J. Environ. Qual., 19: 243-248.
17
Table 1. Yield, irrigation requirement and water productivity under different treatments
Year
Treat- ment
Yield t/ha
Irrigationcm
Rainfallcm
Runoff cm
Deep percol.
Water use, cm
2000
T1 5.57 76.62 80.00 24.00 39.78 92.84 T2 5.39 61.12 80.00 24.00 35.13 81.99 T3 5.98 55.75 80.00 24.00 33.52 78.23 T4 6.14 55.00 80.00 24.00 33.3 77.7 T5 5.84 46.50 80.00 24.00 30.75 71.75
2001
T1 3.94 125.7 36.97 18.49 43.27 100.91 T2 4.47 100.00 36.97 18.49 35.55 82.93 T3 3.31 78.00 36.97 18.49 28.94 67.54 T4 3.49 78.00 36.97 18.49 28.94 67.54 T5 4.03 68.00 36.97 18.49 25.94 60.54
2002
T1 4.73 148.52 66.07 33.03 54.46 127.1 T2 4.7 84.87 66.07 33.03 35.37 82.54 T3 4.28 72.67 66.07 33.03 31.71 74.00 T4 3.95 54.91 66.07 33.03 26.38 61.57 T5 3.93 49.67 66.07 33.03 24.81 57.90
2003
T1 5.31 169.00 44.13 22.06 5.32 185.75 T2 5.58 128.00 44.13 22.06 45.02 105.05 T3 5.27 90.00 44.13 22.06 33.62 78.45 T4 5.46 85.00 44.13 22.06 32.12 74.95 T5 4.97 80.00 44.13 22.06 30.62 71.45
2004
T1 4.63 120.09 26.90 0 0 146.99 T2 5.27 79.24 26.90 0 0 106.14 T3 5.01 58.83 26.90 0 0 85.73 T4 4.39 46.87 26.90 0 0 73.77 T5 5.51 42.5 26.90 0 0 69.40
2005
T1 3.1 129.00 61.62 30.81 47.94 111.87 T2 3.56 82.00 61.62 30.81 33.84 78.97 T3 3.31 59.00 61.62 30.81 26.94 62.87 T4 3.15 54.00 61.62 30.81 25.44 59.37 T5 3.17 54.00 61.62 30.81 25.44 59.37
18
Table 2. Average yield, irrigation water applied, total water use (ET), water productivity
(WP) and irrigation water productivity (IWP) under different water management practices under field condition.
Treat-ments
Yield (t/ha)
Irrigation (cm)
Effective Rainfall
(cm)
Deep percolation
(cm)
ET (cm)
WP
(kg/ha-mm)
IWP
(kg/ha-mm)
T1 4.55 128 39 24 143 3.18 3.55
T2 4.83 89 39 24 104 4.64 5.43
T3 4.52 69 39 8 100 4.52 6.55
T4 4.43 62 39 8 93 4.76 7.15
T5 4.58 57 39 8 88 5.20 8.04
Table 3. Average yield, water use (ET), water productivity (WP) and water productivity
(IWP) under lysimeter. Treat-ments
Yield (t/ha)
Irrigation (cm)
Rainfall (cm)
Runoff (cm)
Deep percolation,
(cm)
Water use
(cm)
WP
(kg/ha- mm
IWP
(kg/ha- mm)
T1 7.54 77.0 56.8 21.0 14.8 101.7 7.4 9.8
T2 7.79 68.2 56.8 21.0 13.0 77.1 10.1 11.4
T3 7.91 48.5 56.8 21.0 9.2 75.0 10.5 16.3
T4 7.98 42.6 56.8 21.0 13.7 68.1 11.7 18.7
T5 7.22 41.8 56.8 21.0 11.9 68.6 10.5 17.3
Table 4. Average estimated amount of NO3-N leaching under lysimeter and field condition
Treatment
NO3-N leaching (kg/ha)
Lysimeter FieldT1 1.59 52.3
T2 1.56 48.3
T3 1.53 23.5
T4 2.00 17.6
T5 1.09 16.9
19
Fig.1. Rainfall amount during crop growing period
2000
0
15
30
45
60
1 7 13 19 25 31 37 43 49 55 61 67 73 79 85 91 97 103
109
115
121
Days from transplanting
Rai
nfal
l (m
m)
2001
0
15
30
45
601 7 13 19 25 31 37 43 49 55 61 67 73 79 85 91 97 103
109
115
121
Days from transplanting
Rai
nfal
l (m
m)
2002
0
20
40
60
80
100
1 7 13 19 25 31 37 43 49 55 61 67 73 79 85 91 97 103
109
115
121
Days from transplanting
Rai
nfal
l (m
m)
2003
0
20
40
60
80
1 7 13 19 25 31 37 43 49 55 61 67 73 79 85 91 97 103
109
115
121
Days from transplanting
Rai
nfal
l (m
m)
2004
0
20
40
60
80
1 7 13 19 25 31 37 43 49 55 61 67 73 79 85 91 97 103
109
115
121
Days from transplanting
Rai
nfal
l (m
m)
2005
0
20
40
60
80
1 6 11 16 21 26 31 36 41 46 51 56 61 66 71 76 81 86 91 96 101
106
Days from transplanting
Rai
nfal
l (m
m)
20
Fig.2(a). NO3-N concentration of drainage water during the crop growing season (Field and
lysimeter) during 2000
Lysimeter I1
0
2
4
6
8
10
0 25 50 75 100 125 150Days after transplanting
NO
3-N
Con
c.,m
g/L
I2
02468
10
0 25 50 75 100 125 150
I3
0
2
4
6
8
10
0 25 50 75 100 125 150
I4
0
2
4
6
8
10
0 25 50 75 100 125 150
I5
0
2
4
6
8
0 25 50 75 100 125 150
Field I1
0
2
4
6
8
10
0 25 50 75 100 125 150Days after transplanting
NO
3 C
onc.
, mg/
L
I2
0
2
4
6
8
10
0 25 50 75 100 125 150
I3
0
2
4
6
8
10
0 25 50 75 100 125 150
I4
0
2
4
6
8
10
0 25 50 75 100 125 150
I5
0
2
4
6
8
10
0 25 50 75 100 125 150
21
Fig.2(b). Cumulative NO3-N concentration of drainage water in field during 2001
Sampling at 38 cm depth-50
-40
-30
-20
-10
018 38 39 55 77 81 105 123
DATN
O3-
N (m
g/)l
T1T2T3T4
DAT
-50
-40
-30
-20
-10
09 19 35 51 67 88 111 123
Sampling at 85 cm depth
NO
3-N
(mg/
l)
T1T2T3T4T5
DAT
-50
-40
-30
-20
-10
09 19 35 51 67 88 111 123
Sampling at 120 cm depth
NO
3 (m
g./l)
T1T4T5
DAT
-60
-50
-40
-30
-20
-10
09 19 35 51 67 88 111 123
Lysimeter
NO
3-N
(mg/
l)
T1T2T3T4T5
22
Fig. 2(c). Cumulative NO3-N concentration of drainage water in field during 2002
Sampling at 38 cm depth-350
-300
-250
-200
-150
-100
-50
08 29 33 43 58 65 87 117 132
DATN
O3-
N (m
g/)l
T1T2T3T5
DAT
-200
-180
-160
-140
-120
-100
-80
-60
-40
-20
0
8 29 33 43 58 65 87 117
Sampling at 85 cm depth
NO
3-N
(mg/
l)
T1T2T3T4T5
DAT
-300
-250
-200
-150
-100
-50
08 29 33 43 58 65 87 117 132
Sampling at 120 cm depth
NO
3 (m
g./l)
T1
T4
DAT
-140
-120
-100
-80
-60
-40
-20
08 29 33 43 58 65 87 117
Sampling from lysimeter
NO
3-N
(mg/
l)
T1T2T3T4T5
23
Fig.2(d). Cumulative NO3-N concentration of drainage water in field and lysimeter 2003
Sampling at 38 cm depth-70
-60
-50
-40
-30
-20
-10
08 29 33 43 58 65 87 117
132
DAT
NO 3
-N C
onc.
, mg/
l
T1
T2
T3
Sampling at 85 cm depth-120
-100
-80
-60
-40
-20
08 29 33 43 58 65 87 117 132
DAT
T1
T2
T4
T5
Sampling at 120 cm depth-80
-70
-60
-50
-40
-30
-20
-10
08 29 33 43 58 65 87 117 132
DAT
T1
T4
Sampling from lysimeter-70
-60
-50
-40
-30
-20
-10
08 29 33 43 58 65 87 117 132
T1
I2
T3
T4
T5
24
Fig. 2(e). Cumulative NO3-N concentration of drainage water in field during 2004
Sampling at 38 cm depth-120
-100
-80
-60
-40
-20
09 19 35 51 67 88 111
DATN
O3-
N (m
g/)l
T1T2T3
DAT
-50
-45
-40
-35
-30
-25
-20
-15
-10
-5
09 19 35 51 67 88 111
Sampling at 85 cm depth
NO
3-N
(mg/
l)
T1T2T3
DAT
-60
-50
-40
-30
-20
-10
09 19 35 51 67 88 111
Sampling at 120 cm depth
NO
3 (m
g./l)
T1T4
25
Fig. 2(f). Cumulative NO3-N leaching rate in rice experiment at BINA field during 2005
DAT
-45
-40
-35
-30
-25
-20
-15
-10
-5
01 2 3 4 5 6 7
Sampling at 38 cm depth
NO 3
-N (
mg.
/l)
T1T2T5
DAT
-45
-40
-35
-30
-25
-20
-15
-10
-5
00 8 24 39 67 93
Sampling at 85 depth
NO 3
-N (m
g./l)
T1T2T3T4T5
DAT
-35
-30
-25
-20
-15
-10
-5
00 8 24 39 67 93
Sampling at 120 cm depth
NO
3-N
(mg.
/l)
T1T4
26
Fig.3(a). NO3-N concentration in soil profile at sowing time and at harvest during 2000
Field
0
1
2
3
4
5
6
0-30 30-60 60-90 90-120Soil depth, cm
NO
3 -N
con
c., m
g/l
MeanofsowingtimeI1
I2
I3
Lysimeter
0
2
4
6
8
10
0-30 30-60 60-90 90-120Soil depth, cm
NO
3 -N
con
c., m
g/l
Mean ofSowingtime I1
I2
I3
I4
27
Fig.3(b). Cumulative NO3-N concentration of soil sample during 2001
Lysimeter
-20
-15
-10
-5
0
0-30 30-60 60-90 90-120Days after transplanting (DAT)
NO
3-N
(mg/
)l
T1T2T3T4
DAT
-20
-15
-10
-5
00-30 30-60 60-90 90-120
Field
NO
3-N
(mg/
l)
T1T2T3T4T5
28
Fig.4. Average NO3-N concentration of drainage water collected from the field
38 cm depth
0
20
40
60
80
9 20 40 65 87 120DAS
NO
3 co
nc. ,
mg/
l
I1I2I3I4I5
85 cm depth
0
20
40
60
80
100
9 20 40 65 87 120DAS
NO
3 co
nc. ,
mg/
l
I1I2I3I4I5
120 cm depth
0
20
40
60
9 20 40 65 87 120DAS
NO
3 co
nc. ,
mg/
l I1I2I5
29
Fig. 5. Average cumulative NO3-N concentration of field and lysimeter soil at harvest
Lysimeter soil
0
6
12
18
0-30 30-60 60-90 90-120Soil depth (cm)
NO
3-N
con
cent
ratio
n (p
pm)
I1I2I3I4I5
Field soil
0
6
12
18
0-30 30-60 60-90 90-120
Soil depth (cm)
NO
3-N
con
cent
ratio
n (p
pm)
I1I2I3I4I5