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Nitrogen Loss Research. Joel Ransom NDSU Extension Agronomist. Background. Nitrogen fertilizer third most costly input in corn production Nitrogen losses can be significant (only ~1/3 of N applied is used by the crop) Off site loses are environmental concerns.
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Nitrogen Loss Research Joel Ransom NDSU Extension Agronomist
Background • Nitrogen fertilizer third most costly input in corn production • Nitrogen losses can be significant (only ~1/3 of N applied is used by the crop) • Off site loses are environmental concerns
Why worry about N use efficiency? • N is biologically and chemically very active in the soil • Each N compound behaves differently in the soil affecting potential for loss • Nitrous oxide is a potent greenhouse gas (impacts climate change?) • Excess nitrate in surface waters causes eutrophication and anoxia
Principles to guide N loss reductions • 4 R’s of nutrient stewardship • Right fertilizer source • Right rate • Right time • Right place
Addressing sources of loss • Volatilization • Placement, urease inhibitors, polymer coated urea, soil moisture status (AA), application timing relative to rain (surface applications) • Leaching and denitrification • Delaying the conversions from ammonium to nitrate • Nitrification inhibitors • Soil temperature at time of application • Polymer coated urea or slow release • Banding vs. broadcasting • Applying nearer the time of greatest uptake • Slow release urea • Split applications
Urease inhibitors • NBPT is the most commonly available and widely tested (Agrotain, SuperU, etc.) • Volatilization of NH3 from urea anytime moisture, urea and urease are present in temperatures that range from 11ºF to 105ºF. • Urease inhibitors block the conversion of urea to ammonia for a period of one to two weeks allowing time for incorporation by rainfall or other means • UAN contains 50% urea
Nitrification inhibitors • Slow the conversion of NH4+to NO3-bykilling or reducing the activity of populations of Nitrosomonasand Nitrococcusbacteria. • Two most common commercial inhibitors are nitrapyrin and DCD
Rate of nitrification Source: Schwab and Murdock, U of K
Release rate of ESN compared to corn N uptake, Manitoba (Heard and Ginter, MAFRD).
Treatments included in recent research • Standard treatment – urea pre-plant incorporated • Instinct – new formulation of nitrapyrin that inhibits nitrification (ammonium to nitrate) • Polymer coated urea – (ESN) coated so that it will release gradually and when temperatures are warmer (30% of total N applied) • Split application – UAN applied at the 6 lf dribbled between rows • Split with UAN + Agrotain Plus – urease inhibitor plus nitrification inhibitor in powder form for ease of mixing with UAN
Experimental locations • 2011 two locations • 2012 and 2013 five locations • 2012 dry but productive year, limited N loss in most environments • 2013 excess moisture early, dry later in the season
Effect of nitrogen management practices on yield of corn in five environments, 2012.
Effect of nitrogen management practices at lowest N rate on yield of corn in five environments, 2012.
Effect of nitrogen management practices on yield of corn in five environments, 2013.
Effect of nitrogen management practices at lowest N rate on yield, all locations, 2013.
Effect of nitrogen management practices at lowest N rate on yield of corn in Casselton, 2013.
Prices • Urea $550/ton ($60 per 100 lbs/N) • ESN $675/ton ($73 per 100 lbs N = 22 lbs N) • 28% UAN $360/ton ($64 per 100 lbs N) • SuperU ~$660-690/ton (~$190 over price of urea) • Instinct ~$11 per acre • Agrotain $56 per ton ($6 per 100 lb N) • Agrotain Plus $65 per ton ($11 per 100 lb N)
Conclusions • No compelling evidence that additives were profitable in any of the environments included • Split applications were both positive and negative depending on the environment • Protection of UAN with urease inhibitor in one environment in 2013 • Additional research would be beneficial to sample additional environments • Rate of Instinct may need adjustment • Ratio of ESN may have been too low to pick up response