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Slow Release Nitrogen for Furrow Irrigated Wheat. Brad Brown Extension Soil and Crop Management Specialist 2010 Idaho Nutrient Management Conference Shoshone, ID March 9, 2010.
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Slow Release Nitrogen for Furrow Irrigated Wheat Brad Brown Extension Soil and Crop Management Specialist 2010 Idaho Nutrient Management Conference Shoshone, ID March 9, 2010
Historically:Preplant N was favored by the industryTo avoid an extra application Spread out the workload Cheaper N
Late winter top-dressed urea is more effective than early fall preplant incorporated urea in 2 out of 3 years:N Immobilization DenitrificationLeaching Volatilization from plantExcessive vegetative growthPhytotoxicity
NRCS 590 Nutrient Management Standard discourages early fall preplant applied N due primarily to risk of nitrate leaching to shallow ground water.
Winter Top-dress risks:Increased compaction NH3 volatilization Phytotoxicity of high N rates Higher application costs (labor, fuel, equipment)
Ideal preplant N source for furrow irrigated winter wheat One application to minimize application costs Avoiding excessive N effects on yield Provide some late season N release for grain filling Minimize volatile N losses
Objective:To evaluate preplant slow release polymer-coated urea N for furrow irrigated SWW wheat
Treatments N rates: 60, 120, 180 lb /A N sources: ESN, Urea, Mix (50:50) N Timing: Early fall preplant, Late fall top-dress, Late winter top-dress
Preplant slow release ESN Increased plant height, N utilization, yield, protein, grain N and apparent N recovery compared to preplant dry urea Was no more effective than late winter top-dressed urea.
Late Winter Topdressed ESN • Reduced plant height, flag leaf Chlorophyll and yield relative to topdressed urea. • Did not release sufficient N for optimal vegetative growth and yield.
Preplant Economic Analysis Assume ESN is $.15 or $.50 more/lb than urea, equal application costs, wheat is $4/bu: Nrate Urea ESN (.15) (.50) 60 543 584 32 11 120 581 635 36 -6 180 621 650 11 -52
Preplant slow release polymer coated urea does have a place in the furrow irrigated wheat system if reasonably priced.
