Spatial variability characteristics of soil available N, P, and K and their influencing factors at the county scale

Abstract

Spatial variability, a major feature of soils, was generally influenced by various factors, relative studies on which laid solid foundations for precision agriculture. In this investigation, method of geostatistics combined with GIS was used to analyze the spatial variability characteristics of soil available nitrogen (SAN), soil available phosphorus (SAP) and soil available potassium (SAK) and their influencing factors in Shuangliu county Sichuan province, China. The results showed that, SAP and SAK were normally distributed through naturally logarithmic transformation. Semivariogram analysis revealed that SAN and SAK were highly spatial correlated, while SAP moderately spatial correlated, and the spatially dependent ranges of SAN, SAK and SAP contents were 21590m, 76903m and 23300m, respectively. Through ordinary Kriging interpolation, SAN, SAP and SAK presented different varying tendencies in the study area. SSR test indicated that SAN was significantly different depending on different soil types; SAP was significantly different depending on terrain conditions and soil parental materials; SAK was strongly affected by soil parental materials. The fertilizer application rate at the regions with high soil available N, P and K contents was obviously higher than that with low soil available nutrient contents.