Spatial Variability of Nitrate in Irrigated Cotton: II. Soil Nitrate and Correlated Variables

Abstract

Abstract The relation between nine soil variables: soil nitrate, % sand, silt and clay, pH, electrical conductivity (EC e ), sodium, potassium, and phosphorus plus petiole nitrate were analyzed by geostatistics and cluster analysis. The samples were collected from 49 sites in a 360 by 360m plot in a commercial cotton ( Gossypium hirsutum ) field. An intensive soils map of the plot was compared to distributions of the soil variables. Models developed from variograms of highly correlated variables were tested using a “jack‐knifing” technique and then the data was block kriged. Soil nitrates were highly correlated with EC e , which has a similar spatial dependence and spatial structure. Percent clay and petiole nitrate were moderately well correlated and had similar spatial structure to each other.