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Optimizing Use of Polymer-Coated Urea for Irrigated Potatoes Production and the Effects on Nitrate Leaching

Start Date: 2013
Principal Investigator: Carl Rosen
Organization: University of Minnesota
Status: Complete

Background Info

Studies of controlled-release nitrogen fertilizer have been conducted for the past 10 years at the Sand Plain Research Farm in Becker, Minnesota, using ESN, a polymer-coated urea product manufactured by Agrium. ESN has been found to be most effective on potatoes when applied at the time of shoot emergence. While results have been promising and adoption by growers has occurred, a product that could be applied prior to planting would be preferable. Duration, also a product from Agrium, has been discussed as a controlled-release nitrogen fertilizer that could be applied to potatoes prior to planting. The thicker coating provides slower urea release, which may make a preplanting application more effective than an application at shoot emergence. This research has been evaluating alternative methods of improving nitrogen use efficiency in irrigated potato production. The specific objectives have been to (1) compare the effects of ESN and Duration on potato yield, grade and quality, relative to an unfertilized control and applications of uncoated urea and ammonium nitrate, and (2) evaluate the use of a chlorophyll meter and petiole nitrate analysis as diagnostic tools for determining the nitrogen status of the crop. An additional objective has been to test the effectiveness of None, a urea source coated with compounds intended to maintain nitrogen in the ammonium form and thus reduce nitrate leaching.

Objectives

Evaluate methods of improving N use efficiency (tuber yield and N uptake per pound of N applied) and the economic efficiency of N fertilizer application (tuber yield per dollar invested in fertilization) in irrigated potato production.

Key Findings

While the two fertilizers and a 1:1 blend of the two all performed almost identically when applied at shoot emergence, Duration produced far higher yields than ESN or the blend when installed before planting.

Duration produced insignificantly higher yields when applied before planting than when applied at emergence, while ESN produced significantly higher yields when applied at emergence than before planting.

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