Tuesday, November 6, 2007
223-24

Evaluation of a Polymer Coated Urea on Irrigated Kidney Bean and Potato Production on a Coarse Textured Soil.

Melissa Wilson1, Carl Rosen, John Moncrief2, Norman Krause3, and Bruce Montgomery4. (1) Soil, Water, and Climate, University of Minnesota, 1991 Upper Buford Circle, St. Paul, MN 55108, (2) Soil Water & Climate Department, University of Minnesota, 1991 Upper Buford Circle, St. Paul, MN 55108, (3) Central Lakes Agricultural Center, Central Lakes College, 1830 Airport Road, Staples, MN 56479, (4) Minnesota, Dept. of Agriculture, Orville L. Freeman Office A-212, 625 Robert Street N, St. Paul, MN 55155-2538

Polymer coated urea (PCU) for irrigated crop production has been documented to reduce nitrate leaching and improve N use efficiency while maintaining yields. Until recently PCU use was not cost-effective for most row crops due to its high price without an offsetting increase in yield or reduction in N rate. A new cost effective PCU, (ESN, Agrium, Inc.) has become available.  Field studies were conducted comparing rate and application timing of ESN and uncoated urea on Montcalm kidney beans (Phaseolus vulgaris L.) and Russet Burbank potatoes (Solanum tuberosum L.) with respect to yield and nitrate leached. Uncoated urea was applied in multiple applications and a single early application was used for ESN. Nitrate leaching was determined by constructing a soil water budget and estimating soil water nitrate concentrations with suction samplers.  In general, ESN applied at emergence resulted in higher marketable potato yields than when applied at planting; although this was only significant in 2005.  Response to ESN compared with uncoated urea depended on year.  In 2005, total yields were not affected by N source, but marketable yields were higher when ESN was applied at emergence. In 2006, potatoes fertilized with ESN at emergence produced higher total yields than those fertilized with split urea applications, although marketable yields were not significantly different. In both years, uncoated urea application resulted in higher kidney bean yields than ESN when applied at sidedress. However, ESN applied to kidney beans at planting resulted in similar yields to those fertilized by uncoated urea at sidedress.  Under the low rainfall conditions of this study, nitrate leaching was not affected by fertilizer source for either crop. Overall, ESN performed better when applied at early sidedress in a long season crop (potato), while the short season crop, kidney beans, produced better yields when ESN was applied at planting.

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