Nitrogen Fertilizer Additives— Which ones work? ones work? R. Jay Goos Professor Department of...
Transcript of Nitrogen Fertilizer Additives— Which ones work? ones work? R. Jay Goos Professor Department of...
Nitrogen Fertilizer Additives—Which ones work?
R. Jay Goos
Professor
Department of Soil Science
North Dakota State University
• Urease inhibitors– Slow conversion of urea to ammonia
– Can reduce ammonia volatilization from surface applications of urea‐containing fertilizers
• Nitrification inhibitors– Slow conversion of ammonium to nitrate
– Can reduce N losses due to leaching or denitrification
• My objective– To summarize my own studies over the past ~30 years with regards to nitrogen fertilizer additives
ATS as a urease inhibitor with UAN
• ATS was shown to inhibit urease, especially with large droplets of UAN
ATS as a urease inhibitor
• Not a general‐purpose urease inhibitor
• Works better with drier soils
• Works better with larger droplet sizes
• Works better with bare soil surfaces
2008 studies, Nutrisphere‐N
• Does Nutrisphere‐N inhibit urease?
• Does Nutrisphere‐N slow ammonia loss?
• Franzen, et al. 2011
2010 study, ammonia loss inhibitors used with UAN
• UAN applied at about 100 kg N/ha, with and without various additives
• Experiment performed four times– Small droplets, bare soil
– Large droplets, bare soil
– Small droplets, 50% stubble cover
– Large droplets, 50% stubble cover
Solution pHUAN 6.9
UAN + ATS 7.2
UAN + CaTS 7.0
UAN + Agrotain 6.9
UAN + Agrotain + CaTS 6.9
UAN + Nutrisphere-LF 3.7
• Goos (paper in review)
Ammonia loss and urease studies, 2011
• Ammonia loss studies, granular urea
• Urea hydrolysis studies, granular urea
• Formal urease inhibition studies– Agrotain Ultra
– Nutrisphere‐N (two sources)
– NZone
– StayN
– NStay
• Urea hydrolysis studies
• Urea pellets placed on top of 2” of moist soil
• Urea hydrolysis followed for 10 days
• Three soils (2‐ND, 1‐IA)
• Urease inhibition studies
• Additives incubated with soil at 2, 20, 200 ppm
• Urease activity determined, 17 hour incubation
Summary of urease, ammonia volatilization studies
• NBPT (Agrotain) most effective
• ATS, CaTS, can reduce ammonia loss, less effective than NBPT
• Nutrisphere‐N has not inhibited urease in any of our studies, effects on ammonia loss small
• NZone, StayN, NStay did not inhibit ammonia volatilization
Nitrification inhibition studies
• Field studies– Spring applied urea granules with DCD
– Spring banded UAN with various products
– Fall applied aqua ammonia with two products
• Lab studies– Several products tested
• Spring application, incorporated, 4 week estimation
Granule Ammonium "half-life" # ofsize Material Average Range sites
g ----------- days -----------
0.01 Urea 9 7-10 130.01 U+DCD 15 12-19 13
0.1 Urea 13 7-19 13 0.1 U+DCD 21 18-22 13
1 Urea 23* 18-28 71 Urea+DCD 25* 22-28 7
• So, what does an ammonium “half‐life” of 10, 15, 20, and 30 days look like?
• Assume a farmer applies 150 lb/N of N as granular urea on May 1st, and tills it in...
Fall N with ATS or N‐Serve
• Aqua ammonia banded in early October 1996Record over‐winter snowfall
• Soil samples taken late in fall, early spring
Ammon. in bands Wheat Total N Late Oct. Mid-May Yield Uptake
ppm N bu/A lb/A Control 2 3 23.6 34.6 Aqua 43 1 37.1 52.9 Aqua + ATS 65 11 47.4 77.0 Aqua + N-Serve 72 14 45.1 72.2
• Goos and Johnson, 1999
Summary of nitrification inhibitor studies
• Nothing works well to protect a spring application. Split application a better option if serious in‐season losses anticipated.
• Some protection from over‐winter losses can be achieved with an inhibitor
• Nitrapyrin (N‐Serve, Instinct) the most effective inhibitor, followed by DCD
• Most of the “new” products do not inhibit nitrification