Nitrification Inhibitors and Controlled Release

Richard Smith UC Cooperative Extension, Monterey County Why Technology? • To improve Nitrogen Use Efficiency - NUE • Given that is so readily leachable, the use of technologies that can reduce the pool of nitrate, but still make N available in adequate quantities and at the right timing for crop growth could improve NUE Nitrification Inhibitors

i' NlltOJIHI Sldlllm I w:; AGR Nitrapyrin (not registered on vegetables)

Urease inhibitor + DCD nitrification inhibitor

E TEC ®

DMPP (not available in the US) Nitrapyrin – low volatility formu lati ion ( not regi stered on vegetables) Nitrification Inhibitors NH4+ NO3- • These chemicals disrupt the activity of and which are responsible for nitrification of to nitrate • If we can keep more of the appppli ed N as ammonium,t, there would be less losses Impact of Dicyandiamide (DCD) on Nitrate Leaching

60

□ .so il 1 "'C 50 [:].so il 1 + DCD .cGJ u --.. ■soil2 ra C 40

■ .soil2 + DCD GJ E -,z :I I -0 30 m 0 ~ ,z t1D 20 .._.E -..ra 10 I~

0 2 4 6 Weeks of incubation Tim Hartz 2011 Controlled Release Fertilizers

Duration. 5 cantro II @ d-Ralease Fertilizer ~

Coated urea prills (polyurethane I and___----1 other coatings) _ -Sure®

-----=---IChains or rings of urea molecules IL(can __be foliar applied) _ Controlled Release Fertilizer one example • The diffusion of nitrate out of the prill is controlled by the thickness of the coating and environmental conditions (temperature) • The coating meters the

released nitrate rather Urea Polyurethane coated than allowing the release Urea of a large quantity that would build up a nitrate pool Other slow release fertilizers

Calcium cyanamid 9=::~~::::::::::::~~===il IL__ I IL_Dry organic materials: _ __ meat,___ fish, bone, feather meals

And many others Factors Affecting NUE • Irrigation management . The key driver in nitrate losses • Shallow rooted crops . Narrow zone where the nitrate must remain 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 some inefficiency in nitrate use Irrigation Impact on Nitrogen Use Efficiency

• One inch of leached water carries 23 lbs of N/A . @ 100 ppm nitrate- NintheN in the solution Root Distribution of Lettuce - 60 days old

Two feet

Bed Width (inches) Drip line Drip line Plant Line Plant Line 5 1015 20 25 Root Nu Root

5 0 10

20 m

30 / cm ber 100 40 50 10 60 70 2

15 pth (inches) ee D 20

25 Weaver and Brunner, 1927 Recent Trials Evaluating Nitrogen Fertili zer TThechno logy in Lettuce Production 2011 Lettuce Yield (T/A) Nitrification Inhibitor Trial

10 150 100 100 + 100 + 4% 100 + 8% Agrotain DCD DCD Lbs N/A 2010 Nitrification Inhibitor Impact on Nitrate in Leachate

50 10 lbs N/A ---0- • 160 lbs N/A --D-- 60 lbs N/A -----£:r--- 110 lbs N/A 40 ······· ·• ········ 60 lbs N/A+Agrotain

-1 110 lbs N/A+Agrotain .... 30 mg N l NN

20 NO3-

10

0 35 40 45 50 55 60 65 DAGWs DCD applied in drip is diluted in a greater volume of soil and may affect its efficacy 2012 Lettuce Fertilizer Trial Ti meli ne

Deep Deep Deep Soil Soil Soil

Mowed Apply Plant Germ Thin 1st 2nd Harvest CC CRF & anticrustant Water fertigation fertigation April June 21 June June July July Aug Aug 26 29 19 27 8 29 Over Over Irrigation Irrigation 2012 Lettuce Fertilizer Trial

Treatment Total N/A • Standard received 65 lbs Untreated 25 N/A and all moderate Standard 155 treatments received 40 lbs

Moderate 105 N/A in two fertigations with UN32 on 29 & 41 days Agrotain Plus 105 after planting G77 105 • D45+sidedress was treated DMPP 105 with 50 lbs N/A on 1st D45 105 fertigation D45 + sidedress 155 • N‐Sure was applied as a D45 155 50:50 mix with UN32 in N‐Sure 105 both fertigations 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 Fer tili ze r

Untreated

Standard Yield Evaluation

35.0

30.0 d d d d c cd

25. 0 b

20.0 /A ss a a a 15.0 Ton

10.0

5.0

0.0 Untreated 155 st 105 mod 105 + 105 + G77 105 + DMPP D45 105 D45 155 SD D45 155 N‐Sure Agrotain Nitrogen Uptake by Lettuce at Harvest 120.0 e e e 100.0 d c c 80.0

60.0 b N/A a Lbs 40.0 a a

20.0

0.0 Untreated 155 st 105 mod 105 + 105 + G77 105 + D45 105 D45 155 D45 155 N‐Sure Agrotain DMPP SD Applied N//pUptake N Ratio Does not account for soil N or leaching losses

3.0

2.5

2.0

151.5

1.0

0.5

0.0 Untreated 155 st 105 mod 105 + 105 + G77 105 + DMPP D45 105 D45 155 SD D45 155 N‐Sure Agrotain Irrigation Events in Relation to Crop ET from Thinning to Harvest t.60

1,,.40

1,,.20 ■ App ied water

1,,.00 ■ Crop IET

0 ,.80

0,.60

0,.40

0 ,.20

0 ,.00 Nitrate‐ N in Soil on Four Dates 45.0

40.0

35.0

...... Untreated 30.0 155 -...... 105 25.0 --++­105 + Agrotain .....105 + G77

20.0 105 + DMPP ---+-D45 105 D45 155 SD 15.0 D45 155 ...... N‐Sure 10.0

5.0

0.0 July 17 July 31 August 7 August 22 Nitrate‐N at 2 –3 Feet in Soil A ugust 15 Average at start of trial (July 2) = 1.6 ppm 20.0 b 18.0 b b 16.0

14. 0 b 12.0 ab 10.0 a 8.0 a

6.0 a a 4.0 a

2.0

0.0 Untreated Standard Moderate Agrotain G77 DMPP D45 105 D45 SD D45 155 Nsure Plus Irrigation Events in Relation to Crop ET from Thinning to Harvest t.60

1,,.40

1,,.20 ■ App ied water

1,,.00 ■ Crop IET

0 ,.80

0,.60

0,.40

0 ,.20

0 ,.00 Nitrate‐N at 2 ‐ 3 Feet in Soil Augustst 31

8.0 b 7.0 b 6.0

5.0 b

4.0

3.0 a a 2.0 a a a a 1.0 a

0.0 Untreated Standard Moderate Agrotain G77 DMPP D45 105 D45 SD D45 155 Nsure Plus Summary

• 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 Summary

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

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