Nitrification Inhibitors and Controlled Release Fertilizers

Richard SmithUC Cooperative Extension, Monterey County

Why Nitrogen Fertilizer Technology?Technology?

• To improve Nitrogen Use p gEfficiency - NUE

• Given that nitrate is so readily• Given that nitrate is so readily leachable, the use of technologies h d h l fthat can reduce the pool of

nitrate, but still make N available in adequate quantities and at the right timing for crop growth couldright timing for crop growth could improve NUE

Nitrification Inhibitors

Nitrapyrin (not registered on vegetables)

Urease inhibitor + DCD nitrification inhibitor

DMPP (not available in the US) Nitrapyrin – low volatility f l ti ( t i t dformulation (not registered on vegetables)

Nitrification Inhibitors

NH4+ NO3-

• These chemicals disrupt the activity of Nitrosomonas andactivity of Nitrosomonas and Nitrobacter bacteria which are responsible for nitrification ofresponsible for nitrification of ammonium to nitrate

• If we can keep more of the applied N as ammonium, there app ed as a o u , t e ewould be less leaching losses

Impact of Dicyandiamide (DCD)Ni L hion Nitrate Leaching

Tim Hartz 2011

Controlled Release FertilizersCo t o ed e ease e t e s

Coated urea prills (polyurethaneand other coatings)

Chains or rings of urea moleculesg(can be foliar applied)

Controlled Release Fertilizerone exampleone example

• The diffusion of nitrate out of the prill is pcontrolled by the thickness of the coating and environmental conditions (temperature)

• The coating meters the released nitrate rather than allowing the release

Urea Polyurethane coatedUreathan allowing the release 

of a large quantity that would build up a nitrate 

Urea

would build up a nitratepool

Other slow release fertilizersOt e s o e ease e t e s

Calcium cyanamid Dry organic materials:meat, fish, bone, feather meals

And many othersAnd many others

Factors Affecting NUE• Irrigation management The key driver in nitrate losses

• Shallow rooted cropsShallow rooted crops Narrow zone where the nitrate must remain in order to be used by the cropremain in order to be used by the crop

• Short‐term, high nitrogen demand Difficult to supply large quantities of N for a short period of time without suffering p gsome inefficiency in nitrate use

Irrigation Impact on Nitrogen Use Efficiency

• One inch of leached waterleached water carries 23 lbs of N/AN/A @ 100 ppm nitrate-

N in the soilN in the soil solution

Root Distribution of Lettuce - 60 days old

Two feetBed Width (inches)

5 10 15 20 25

5 01020

Plant Line Plant LineDrip lineDrip line

Root N

um

Two feet

epth

(inc

hes)

10

15

304050 60 70

mber / 100 cm

2

De

20

25

Weaver and Brunner, 1927

Recent Trials Evaluating Nitrogen F tili T h lFertilizer Technologyin Lettuce Production

2011 Lettuce Yield (T/A) Nitrification Inhibitor TrialNitrification Inhibitor Trial

Lbs N/A

2010 Nitrification Inhibitor Impact on Nitrate in Leachate

40

50 10 lbs N/A 160 lbs N/A 60 lbs N/A 110 lbs N/A 60 lbs N/A+Agrotain

N m

g N

l-1

30

60 lbs N/A+Agrotain 110 lbs N/A+Agrotain

NO

3-N

10

20

35 40 45 50 55 60 650

10

DAGW

35 40 45 50 55 60 65

s

DCD applied in drip is dilutedin a greater volume of soiland may affect its efficacy

2012 Lettuce Fertilizer TrialTi liTimeline

MowedCC

ApplyCRF

Plant & anticrustant

GermWater

Thin 1st

fertigation2nd

fertigationHarvest

Deep Soil

Deep Soil

Deep Soil

g g

April June  21 June26

June29

July 19

July 27

Aug8

Aug 29

Over Irrigation

Over Irrigation

2012 Lettuce Fertilizer Trial2012 Lettuce Fertilizer Trial

• Standard received 65 lbs Treatment Total N/AN/A and all moderate treatments received 40 lbs N/A in two fertigations

/Untreated 25Standard 155

N/A in two fertigations with UN32 on 29 & 41 days after planting

Moderate 105Agrotain Plus  105G77 105 • D45+sidedress was treated 

with 50 lbs N/A on 1st

fertigation

G77  105DMPP 105D45 105 fertigation

• N‐Sure was applied as a 50:50 mix with UN32 in 

D45 105D45 + sidedress 155D45 155

both fertigationsN‐Sure  105

Injection of fertilizer treatments:• Each treatment had its own main• Treatments were injected into the ports and each main delivered the N to the associated beds

Excellent Response to F tiliFertilizer

Untreated Standard

Yield EvaluationYield Evaluation35.0

25 0

30.0 d                                                      c                                                    cd

d            d d

20.0

25.0

b               

s/A

10.0

15.0a                          a a

Tons

5.0

0.0Untreated 155 st 105 mod 105 + 

Agrotain105 + G77 105 + DMPP D45 105 D45 155 SD D45 155  N‐Sure 

Nitrogen Uptake by Lettuce at Harvest

120.0

ee e

100.0 d

c

e

c

60.0

80.0

bN/A

40.0a a aLb

s

20.0

0.0

Untreated 155 st 105 mod 105 + Agrotain

105 + G77 105 + DMPP

D45 105 D45 155 SD

D45 155  N‐Sure 

Applied N/Uptake N Ratiopp / pDoes not account for soil N or leaching losses

3.0

2.5

1 5

2.0

1.0

1.5

0.5

0.0Untreated 155 st 105 mod 105 + 

Agrotain105 + G77 105 + DMPP D45 105 D45 155 SD D45 155  N‐Sure 

Irrigation Events in Relation to Crop ET from Thinning to Harvest

Nitrate‐N in Soil on Four DatesNitrate N in Soil on Four Dates

40.0

45.0

35.0

Untreated

25.0

30.0155

105

105 + Agrotain

105 + G77

15.0

20.0 105 + DMPP

D45 105

D45 155 SD

D45 155 

5.0

10.0

N‐Sure 

0.0July 17 July 31 August 7 August 22

Nitrate‐N at 2 – 3 Feet in Soil A t 15August 15

Average at start of trial (July 2) = 1.6 ppm20.0

b

14 0

16.0

18.0

b

b

b

10.0

12.0

14.0

aab

b

6.0

8.0

a

a

a

2.0

4.0

aaa

0.0Untreated Standard Moderate Agrotain 

PlusG77 DMPP D45 105 D45 SD D45 155 Nsure

Irrigation Events in Relation to Crop ET from Thinning to Harvest

Nitrate‐N at 2 ‐ 3 Feet in Soil A st 31August 31

8.0

b

6.0

7.0b

b

4.0

5.0 b

3.0

4.0

aa a

1.0

2.0

a a a aa

0.0Untreated Standard Moderate Agrotain 

PlusG77 DMPP D45 105 D45 SD D45 155 Nsure

SummarySummary

• All nitrogen technologies showed great promise for improving nitrogen use efficiency

• Moderate level of N fertilization had improved yield with Agrotian Plus, DMPP, D45 and N-Sure under the conditions in this trial

SummarySummary

• Given the great NUE of the CRF, the rates should be examined to see if we can reduce the loss of nitrate beyond the rootzonenitrate beyond the rootzone observed in this trial

SummarySummary

• The use of these technologies does not preclude the need for pgood irrigation management