Spatial Distribution of pH in the Soil Profiles of Representative Soil Series from Rice Producing Area, District Sheikhupura

Soil pH is one of the chemical properties influencing the nutrient bioavailability. Most of the Pakistani soils are calcareous in nature. Keeping in view the limitations of classical statistics for explaining spatial heterogeneity a survey in the farmer grown rice fields was conducted for mapping of soil pH down the soil profile up to the depth of 100 cm using geo-statistics and GIS as a diagnostic tool. One hundred and seventy five soil samples were collected from the representative soil series of rice producing district Sheikhupura. Sampling was done from five depths of 0-12, 12-24, 24-36, 36-60 and 60-100 cm. Soil profiles were excavated and samples were collected from the five depths to examine the variation of pH down the soil profile. Results indicated that soil pH at different depths was 7.80 ±0.45, 8.09 ± 0.42, 8.29±0.50, 8.39±0.54 and 8.47 ± 0.57 at 0-12, 12-24, 24-36, 36-60 and 60-100 cm depth, respectively. When geo-statistical analyses of the data were performed soil pH at all depths was found moderately to strongly spatial dependent (Nugget sill ratio <35). Maps were prepared to classify the whole district in to different pH management zones for producing regional scale information.