if you want a copy of this presentation, or an archive of...
TRANSCRIPT
• If you want a copy of this presentation, or an archive of my papers on nitrogen fertilizer additives, my e-mail is:
Recent evaluations of nitrogen fertilizer additives
R. Jay Goos
Professor
Department of Soil Science
North Dakota State University
• 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
• "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
• "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?
Criteria for a urease inhibitor for surface application to granular urea
• How much soil does a urea granule react with?
• 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
• 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.
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
Urea remaining (% Inhibition)
Source: SSSAJ 77:1418-1423
Three moist soils, ~90 lb N/A, urea granules versus urea granules treated with Agrotain Ultra, NZone, or Nutrisphere-N (two sources)
Source: Proc. Great Plains Soil Fert. Conf. 14:30-36
Urea remaining (% Inhibition)
Source: SSSAJ 77:1418-1423
• Ammonia loss studies, 2 soils
• Urea granules, versus urea granules treated with Agrotain Ultra, NZone, or Nutrisphere-N
Source: Proc. Great Plains Soil Fert. Conf. 14:30-36.
UAN applied at ~90 lb N/A, with Nutrisphere-N, ATS, CaTS, Agrotain Ultra, or CaTS + Agrotain Ultra
Ammonia loss measured for 2 weeks
Source: Comm. Soil Sci. Plant Analysis 44:1909-1917.
• 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)
Goos and Guertal, unpublished
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
Source: in review, SSSAJ
Source: in review, SSSAJ
• 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
• 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
• 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.
• 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
• If you want a copy of this presentation, or an archive of my papers on nitrogen fertilizer additives, my e-mail is: