Spatial variability of soil properties and wheat yields in an irrigated field

An irrigated farmer's field at Hafizabad village in Dera Ismail Khan Distri ct of Northwest Frontier Province of Pakistan was sampled at a regular grid spacing of 50x15 m from surface (15 cm) to study the spatial variability o f soil properties and wheat yield. The farm measured 250x75 m. Soil samples collected were analyzed for soil pH, lime content, organic matter, mineral nitrogen (N), ammonium bicarbonate (AB)-DTPA-extractable phosphorus (P) an d potassium (K), and soil texture. A uniformly trial on wheat with a unifor m rate of 120 kg N ha(-1), 90 kg P2O5 ha(-1), and 60 kg K2O ha(-1) was laid out. The results showed that the soil P had the highest coefficient of var iation (CV 46%) followed by organic matter (36.20%) and clay content (33.81 %). Grain yield had also a considerable variation in the field (CV=31.84%). Geostatistical technique of semivariogram analysis showed that mineral N, AB-DTPA-extractable K, sand, silt, and clay content had the strong spatial structure. Maps of soil fertility and crop productivity of the farm was pre pared using modern geostatistical technique of kriging. The farm was divide d into different management zones based on these maps for fertility managem ent.