If you want a copy of this presentation, or an archive of my papers on nitrogen fertilizer additives, my is:

Transcription

1 If you want a copy of this presentation, or an archive of my papers on nitrogen fertilizer additives, my is: rj.goos@ndsu.edu

2 Recent evaluations of nitrogen fertilizer additives R. Jay Goos Professor Department of Soil Science North Dakota State University

3 The one-minute backgrounder... Urease inhibitors slow the conversion of urea to ammonia Useful when urea-containing fertilizers are left on the soil surface Nitrification inhibitors slow the conversion of ammonium to nitrate Useful when nitrate can be lost under wet conditions

4 "Old" nitrogen fertilizer additives Nitrapyrin (N-Serve) Nitrification inhibitor Dicyandiamide (DCD) N fertilizer and nitrification inhibitor ATS, a sulfur fertilizer Weak inhibitor of nitrification and urease Most effective when banded with UAN NBPT (Agrotain, Arborite, Factor, etc.) Urease inhibitor

5 "New" nitrogen fertilizer additives Nutrisphere-N Claimed to inhibit urease and nitrification NZone Claimed to slow N loss Instinct Micro-encapsulated nitrapyrin Nitrification inhibitor How well do these new products perform?

6 Criteria for a urease inhibitor for surface application to granular urea How much soil does a urea granule react with?

7 If the urea granule is 10 mg of urea 4500 μg of N If hydrolysis takes ~4 days If the soil urease activity is ~5-10 μg N g -1 h -1 Minimum soil needed, roughly 5-10 grams

8 Agrotain Ultra applied at 3 quarts/ton, s.g. 1.1 Concentration a.i. on fertilizer, 0.09% wt/wt 10 mg urea pellet contains ~ 9 μg of NBPT Concentration of NBPT in soil, ~ 1-2 ppm if reaction zone is 5-10 grams.

9 Three soils, 10 g, 500 ppm urea, 1, 5, 50, 500 ppm MIP as NSN, vs. 1, 5 ppm NBPT as Agrotain Ultra. 12 h incubation

10 Urea remaining (% Inhibition) Source: SSSAJ 77:

11 Three moist soils, ~90 lb N/A, urea granules versus urea granules treated with Agrotain Ultra, NZone, or Nutrisphere-N (two sources)

12 Source: Proc. Great Plains Soil Fert. Conf. 14:30-36

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14 Urea remaining (% Inhibition) Source: SSSAJ 77:

15 Ammonia loss studies, 2 soils Urea granules, versus urea granules treated with Agrotain Ultra, NZone, or Nutrisphere-N

16 Source: Proc. Great Plains Soil Fert. Conf. 14:30-36.

17 UAN applied at ~90 lb N/A, with Nutrisphere-N, ATS, CaTS, Agrotain Ultra, or CaTS + Agrotain Ultra

18 Ammonia loss measured for 2 weeks

19 Source: Comm. Soil Sci. Plant Analysis 44:

20 Urea granule nitrification studies Intact urea granules placed in moist soil with very minimal water movement Urea Urea + Nutrisphere-N Urea + NZone Urea + Instinct Urea + NBPT + DCD (SuperU)

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22 Goos and Guertal, unpublished

23 Nitrification inhibitor active ingredient study Four soils, 10 g, incubated for 1, 2, 3, 4 weeks 0, 0.2, 1, 5, 25 ppm of a.i. of N-Serve, Instinct, DCD, Nutrisphere-N, and ATS

24 Source: in review, SSSAJ

25 Source: in review, SSSAJ

26 Summary of studies Urease inhibitors to be applied to the surface of granular urea need to active at very low concentrations of a.i. in the soil (1-5 ppm) NBPT meets this criterion Nutrisphere-N has been an ineffective inhibitor of urease in all of our studies to date

27 Summary of studies (continued) Nutrisphere-N and NZone had no effect on urease or ammonia loss when applied on granular urea, but Agrotain Ultra reduced ammonia loss Nutrisphere-N gave a small reduction in ammonia loss when applied with UAN, but ATS, CaTS, and Agrotain Ultra were more effective

28 Summary of studies (continued) Nutrisphere-N and NZone had no effect on nitrification when applied to granular urea. Nitrification was slowed by Instinct and SuperU. Encapsulation of nitrapyrin to make Instinct reduced its effectiveness, compared to unencapsulated nitrapyrin. Nutrisphere-N showed little ability to inhibit nitrification.

29 Urea granule hydrolysis and volatilization studies supported by Agrotain International UAN ammonia loss study supported by Tessenderlo-Kerley The other studies supported by the ND Agricultural Experiment Station

30 If you want a copy of this presentation, or an archive of my papers on nitrogen fertilizer additives, my is: rj.goos@ndsu.edu