Monday, November 13, 2006 - 3:50 PM

Agricultural Management of Enhanced Efficiency Fertilizers with High Value Crops: Potatoes.

Carl J. Rosen, Univ of Minnesota, 1991 Upper Buford Circle, Dept of Soil, Water, and Climate, St. Paul, MN 55108, Bryan Hopkins, Idaho Falls R&E Center, 1776 Science Center Dr Ste 205, Idaho Falls, ID 83402-1575, Terry Tindall, J.R. Simplot Company, PO Box 70013, Boise, ID 83702, and Trent Taysom, Univ of Idaho Research and Extension Ctr., 1776 Science Center Dr, Suite 205, Idaho Falls, ID 83402-1575.

Potatoes are a relatively shallow rooted crop with high nitrogen and water requirements.  Typical nitrogen management for irrigated potato production includes a portion applied preplant or at planting, a portion at cultivation, and the remainder via 4-8 fertigation events.  Use of controlled release or enhanced efficiency fertilizer represents a possible alternative to conventional management.  Advantages include fewer applications and the potential for less nitrate leaching losses.   Previous studies with controlled release fertilizers on potatoes, however, have shown variable results ranging from negative response or no response to positive response.  The variable results were in part due to different climatic/weather conditions under which the studies were conducted as well as release rates of some products that were too slow to meet the demands of the crop early in the season.  Some of the more recent controlled release fertilizer products available on the market have shown promise for synchronizing release rates with nitrogen uptake requirements of the potato crop.  This presentation will focus on field experiments with irrigated potatoes conducted over the past few years in the upper Midwest and Northwest U. S. comparing controlled release fertilizers with conventional fertilizer management systems.   The primary objectives were to evaluate various rates and application timing of controlled release fertilizers on yield and quality responses as well as to determine their effects on nitrate leaching losses.