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Abstract
Wilson, M.L., J.F. Moncrief, and C.J. Rosen .2008. Kidney bean (Phaseolus vulgaris L.)
production on an irrigated, coarse-textured soil in response to polymer
coated urea and tillage: II. Plant N accumulation, nitrate leaching and
residual inorganic soil N. JEMREST 5:77-91.
Kidney
bean (Phaseolus vulgaris L.) production in Minnesota is inherently at risk for
nitrate (NO3)
leaching since the crop is typically grown on irrigated coarse-textured
soils. These soils contain a dense Bt layer, which growers feel must be
broken up through deep plowing to reduce severity of root rot. This study was
conducted to determine the effects of polymer coated urea (PCU, Agrium U.S.
Inc. and WSPCU, Specialty Fertilizer Products) and tillage depth on water
percolation, nitrate leaching, and plant nitrogen (N) uptake. In a split plot
design, deep and shallow tillage (plow depths of 47 and 29 cm, respectively)
were whole plots while N treatments were subplots. Three rates of emergence
applied PCU were compared with equivalent rates of urea split applied at
emergence and prebloom. Along with a 0 N control, additional treatments
included one rate of each N source, including WSPCU, applied at planting.
Differences between tillage treatments were not found except as interactions
with N treatment. In dry years, emergence applied PCU resulted in reduced
grain N uptake and more cumulative NO3 leaching than split applied urea. In a wet
year, however, emergence applied PCU resulted in similar plant N uptake and
significantly less NO3 leaching that split
applied urea. Planting applied PCU resulted in similar plant N uptake and
generally less NO3 leaching compared with
split applied and planting urea, regardless of leaching conditions. In dry
years, planting applied WSPCU resulted in similar grain N uptake and NO3 leaching as planting applied urea and PCU.
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