Field Scale Variations in Soil Properties for Spatially Variable Control: A Review

Abstract

This article reviews the widely scattered information on spatial variability of field-scale properties. It mainly addresses the variations in properties that influence nitrate accumulation and movement resulting from the agricultural activities in the root zone. The drive for this research comes from the perception and evidence of widespread contamination arising from production agriculture. The information is useful in the spatial management of soil for prevention of non-point source groundwater contamination from production practices. The review includes most of the static soil properties, one water transport property, some soil fertility variables, and crop yield. It examines various investigations and parameters identifying the magnitude of variability, and spatial correlation values for a given property are provided in a tabular form. Various sources of spatial variability, as well as methods of evaluating soil variability, are also discussed. For static soil properties, the range of coefficient of variation (CV) value was found to be small given the diversity of soils and field sizes on which the observations were conducted. The selected soil fertility variables and crop yield exhibited intermediate variations. However, CVs were considerably higher for the investigated transport property than those of static soil properties. The static soil properties and fertility variables were found to be correlated over a much larger distance than the transport property. If there was no variability, production through traditional practice with proper adjustment for field conditions would be the most appropriate choice. However, variations in soil and crop growth properties have led to attempts to understand these variations and application of spatially variable control in production agriculture.