Spatial variability of soil properties and delineation of soil management zones of oil palm plantations grown in a hot and humid tropical region of southern India

Sustainable soil nutrient management with proper understanding of spatial variability of soil properties helps in enhancement of crop productivity and avoiding soil degradation. It has more importance in oil palm plantations, since the area under oil palm cultivation is on rise globally. Moreover, the crop is a nutrient-requiring one and effective nutrient management contributes about 50% of fresh fruit bunch (FFB) production. Therefore, the present study was carried out to assess spatial distribution of soil properties and to delineate soil management zones (MZs) in oil palm plantations of a hot and humid tropical region of India for efficient soil nutrient management. A total of 180 geo-referenced representative soil samples (from 0 to 0.20 m depth) were collected from oil palm plantations of Pedavegi and Denduluru mandals of west Godavari district of Andhra Pradesh, India. Collected soil samples were processed and analysed for soil properties like pH, electrical conductivity (EC), soil organic carbon (SOC), available phosphorus (P), available potassium (K), exchangeable calcium (Ca), exchangeable magnesium (Mg), available sulphur (S) and available boron (B). The values of soil properties varied widely with low (7.7%) to moderate (29.0 to 77.4%) coefficient of variations. Semivariogram analysis and ordinary kriging revealed varied spatial distribution pattern with moderate to strong spatial dependence for most of the soil properties. Development of the MZs was carried out by principal component (PC) analysis and fuzzy c-means clustering. Three PCs with eigen values > 1 and accounting 60.31% of total variance were used for further analysis. On the basis of fuzzy performance index and normalized classification entropy, three MZs were identified. The MZs differed significantly with respect to studied soil properties. Thus, the study emphasized that the methodology for delineating MZs could be effectively used for site-specific soil nutrient management in oil palm plantations and other crops for maximizing crop production in the study area.