Delineation of site-specific management zones based on soil properties for a hillside field in central China

Abstract

Currently, efficient and cost-efficient methods are needed to manage fields in order to maximize economic return, minimize environmental impact, and improve soil and crop site-specific management. Management zones (MZs) of uniform production potential may offer a solution to the problems associated with grid soil sampling while still effectively describing variability in soil properties. In this study, a hillside field of 4 ha was selected as the study site and 111 soil samples were taken from the topsoil (0–20 cm), on an ∼20-m grid. Soil samples were analyzed for pH, organic matter, active soil organic matter, total nitrogen, alkalytic nitrogen, available phosphorous, available potassium and cation-exchange capacity. Their spatial variability was analyzed and spatial distribution maps were constructed using geostatistical techniques. Principal component analysis (PCA) and fuzzy c-means clustering algorithm were then performed to delineate MZs, and eigenvalues were used to select the principal components (PCs) for cluster analysis. Fuzzy performance index and normalized classification entropy were used to determine the optimum cluster number. The results revealed that the optimum number of MZs for this study area was three and analysis of variance indicated that the MZs were reasonable for the area. Based on the description of MZs, it was concluded that the area could be managed in a site-specific way.