Delineation and Analysis of Site-Specific Management Zones

CHARACTERIZING SOIL PHYSICAL AND CHEMICAL PROPERTIES INFLUENCING CROP YIELD USING SOIL ELECTRICAL CONDUCTIVITY^*

N.R. Kitchen, K.A. Sudduth, S.T. Drummond
Agricultural Research Service, Cropping Systems and Water Quality Research Unit
Columbia, Missouri, USA

ABSTRACT

With the advent of site-specific management strategies, interest has intensified to cost-effectively measure spatially-variable soil physical and chemical characteristics. The objective of this research was to investigate the relationship of apparent soil electrical conductivity (EC_a) to various soil physical and chemical properties for claypan, Mississippi delta, and deep loess hill soils. We developed procedures using EC_a to accurately and quickly map topsoil depth for claypan soils. Because topsoil depth also affects P in the claypan soil profile, EC_a data could be used for developing more precise variable-rate fertilizer maps. Soil EC_a accurately estimated soil texture variation across Mississippi delta fields. Soil EC_a also accurately predicted Ca, Mg, K, and CEC for these soils. For loess hill soils, EC_a variation predicted well Ca and Mg, but was a poor predictor Bt horizon depth. With all soil EC_a sensing, the need for ground truthing for each soil type and location is essential for understanding the potential for precision agriculture.

*Presented at the Second International Geospatial Information in Agriculture and Forestry Conference, Lake Buena Vista, Florida, 10-12 January 2000.

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