Brian J Wienhold and John W Doran Contents

11.1 Introduction 211

11.2 Methods 211

11.3 Results and Discussion 212

11.4 Conclusions 214

11.5 Authors' Note 214

References 214


Soils commonly exhibit spatial variability in inherent soil properties such as texture, depth of topsoil, and organic C content. Inherent soil properties influence many chemical and biological properties that ultimately affect plant growth. Traditional methods of soil sampling (grid sampling, stratified sampling) require large inputs of labor and are expensive. The labor and cost requirements associated with traditional sampling often make it prohibitive to sample at a density that will accurately measure the spatial patterns present in a field. In agricultural fields, crops growing in areas of a field differing in inherent soil properties may differ in yield potential. Because yield varies within a field, the potential exists for improving crop utilization of inputs such as lime and fertilizer by varying application rates based on spatial patterns in inherent soil properties. To realize this potential, more efficient methods for delineating spatial variability in inherent soil properties are needed. Apparent soil electrical conductivity (ECa) measured using electromagnetic induction combined with Global Positioning System (GPS) has potential for delineating soil variability and as an aid in selecting soil sampling locations (Lesch et al., 1995). A study was conducted to determine the relationship between ECa and inherent soil properties that potentially affect soil-water dynamics and chemical and biological properties.


This study was conducted in central Nebraska, near Bruning. The 20 ha field was in a soybean (Glycine max L.), winter wheat (Triticum aestivum L.), sorghum (Sorghum bicolor (L.) Moench) rotation and had been cropped to soybeans the previous year. Soils at this site are a Crete silt loam with small areas of Butler silt loam and Hasting silt loam. In June 2003, an ECa survey was conducted using an

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