Slow Release Nitrogen for Furrow Irrigated Wheat

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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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HistoricallyPreplant N was favored by the
industry To avoid an extra application Spread
out the workload Cheaper N
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Late winter top-dressed urea is more effective
than early fall preplant incorporated urea in 2
out of 3 yearsN Immobilization Denitrification
Leaching Volatilization from plantExcessive
vegetative growthPhytotoxicity
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NRCS 590 Nutrient Management Standard discourages
early fall preplant applied N due primarily to
risk of nitrate leaching to shallow ground water.
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Winter Top-dress risks Increased
compaction NH3 volatilization Phytotoxicity of
high N rates Higher application costs (labor,
fuel, equipment)
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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

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Objective To evaluate preplant slow release
polymer-coated urea N for furrow irrigated SWW
wheat
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Treatments
N rates 60, 120, 180 lb /A N sources ESN,
Urea, Mix (5050) N Timing Early fall
preplant, Late fall top-dress, Late winter
top-dress
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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.

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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.

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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 58
1 635 36 -6 180 621 650 11 -52
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Preplant slow release polymer coated urea does
have a place in the furrow irrigated wheat system
if reasonably priced.
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Thank you for your interest