| Abstract Detail
Production and Management Hopkins, Bryan G. [1], Ellsworth, Jason W. [1], Bowen, Thomas R. [1], Cook, Aaron G. [1], Oborn, Ralph A. [2]. Variable Rate Nitrogen Fertilization in Potatoes. POTATOES (Solanum tuberosum) are particularly sensitive to nitrogen (N) nutrition. The fertilizer N needed is related to both residual soil nitrate and yield potential and is spatially variable. Three methods of determining spatially unique N fertilizer needs were compared to a uniform application in five potato fields, with calcareous outcroppings, in Idaho each year of the study (2003-2005). The methods used to divide the fields into management zones included: 1) grid mapping, 2) bare soil imagery with intensive soil sampling and site analysis, and 3) apparent soil electrical conductivity (ECa) mapping as an added layer to the imagery method. Grid mapping recommendations were based solely on residual soil nitrate values, whereas the imagery and EC methods included zonal adjustments for variable yield goals. Twenty m wide strips of each management type were established field length, with yields measured in three management zones of each strip. Only the bare soil imagery method of identifying soil and yield goal zones resulted in significant increases in tuber yield and quality parameters, with increases of total (3.1 Mg ha-1) and US No. 1 (4.0 Mg ha-1) yields over the traditional method. Incidence of hollow heart was also significantly reduced with variable rate N application in the first year (2003). It is apparent from this work that bare soil imagery is an effective means to divide fields with calcareous outcroppings into management zones. These management zones should be sampled separately and assigned a unique yield goal in order to determine a nitrogen recommendation for each. Variably applying N based on grid sampling did not improve yields, due mostly to uniform residual soil nitrate values observed in this study. Adding EC as a layer of information to imagery did not improve the results, but more work is needed to calibrate EC in Idaho soils.
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1 - University of Idaho, Plant, Soil, & Entomological Sciences, 1776 Science Center Dr., Suite 205, Idaho Falls, Idaho, 83402-1575, United States
2 - Cascade Earth Sciences, Env., 1177 Call Place, Suite B, Pocatello, Idaho, 83201, United States
Keywords:
variable rate
nitrogen
fertilization
imagery
EC
grid sampling.
Session: PAA12-5
Location: Hall of Ideas Room E/Monona Terrace
Date: Tuesday, July 25th, 2006
Time: 9:30 AM
Abstract ID:312 |
