Spatial variability of soil properties and cereal yield in a cultivated field on sandy soil

Sandy soils are used in agriculture in different regions of the world. In Poland soils derived from sands occupy about 50% of agricultural area. Productivity of the soils depend on the soil properties that vary in the scale of field. This study aimed at determining and mapping the within-field variation of soil physical and chemical properties and grain yield of oats, rye, oats and triticale in 2001, 2002, 2003, 2015, respectively. The experiment was set up in a field (200×50m) on sandy soil in Trzebieszów (region Podlasie, Poland). The soil measurements included sand, silt, clay, and organic carbon (SOC) contents, cation exchange capacity (CEC), pH in the topsoil (0–10cm) and subsoil (30–40cm) layers in 2001, and water content and bulk density in the topsoil layer in spring and summer 2002–2003. The yields of oats were assessed in 2001 and 2003 and those of rye and triticale in 2002 and 2015, respectively. The soil properties and cereal yields were determined at 33–55 points in a grid evenly covering the whole field area. The results were analyzed using classic statistics and geostatistics by constructing semivariograms and 2D mapping by Inverse Distance Weighting (IDW). The cereal grain yields were significantly positively correlated with the topsoil water content (SWC) (r=0.295–0.711), clay content (r=0.081–0.174), and SOC in the subsoil (r=0.208–0.271) and CEC in both layers (r=0.123–0.298) and negatively correlated with bulk density (BD) (r=–0.065 to −0.279). The spatial dependence determined by the “nugget-to-sill” ratio was moderate or weak for the silt and clay content, CEC, and pH (29–79%) and strong for SOC, BD, SWC, and crop yield (0.2–13.2%). The effective range of the spatial dependence for all studied quantities varied from 9.9 to 120m. The cereal yields were positively and significantly correlated between all study years (r=0.141–0.734), which indicates inter-annual similarity in their spatial distribution. The 2D maps based on the IDW allowed assessing how gradual or sharp the changes in the studied quantities from one place to another are. Similar spatial patterns of the SWC, SOC and CEC, and crop yields were observed. This is of importance in precise and sustainable field management aimed at increasing and aligning spatial crop productivity of the studied low-productivity sandy soils that will have to be used in crop production due to the current shortage of land resources and food supplies on a global scale.