Identifying Positions in Two Sugarcane Fields for Studying Phosphorus Movement Using Spatial Variability.

Evaluation of the of heterogeneity in two sugarcane fields, each with different soil orders, in terms of soil properties help to explain the applicability of a water quality model for phosphorus (P) movement. In this study, horizon depths, depths to limestone rock, total carbon, and total P were used to predict unknown values at unsampled positions in two sugarcane fields in Hendry County, Southwest Florida. A 12 hectare sugarcane field with Margate soil series (Siliceous, and hyperthermic Mollic Psammaquents) and a 12 ha sugarcane field with Immokalee soil series (Siliceous, hyperthermic Arenic Alaquods) in Hendry County, Southwest Florida were used for the study. Eighty uniformly distributed sample positions and 20 randomly distributed sample positions in each field were sampled to evaluate spatial variability. Soil was extracted to limestone for Margate soil and Bh horizon for Immokalee soil using a 7.5 cm auger. The soil horizon depths and depth to limestone rock were measured. Soil samples taken at 30cm increments were analyzed for total carbon and total P. The data were subjected to principal component analysis to identify the spatial variability structure. Ordinary Kriging on points was used to carry out the spatial interpolation on the collected data. Field positions for monitoring P movement were selected by attribute ranges of measured soil property values using ArGIS software. All measured soil properties varied spatially, with total carbon and total P varying significantly with soil depth.