Mapping Soil Chemical Properties for Diversifying Land Use In An Agro-Ecological Sub Region of Punjab, India Using Geographic Information System.

Continuous practice of rice – wheat cropping system with high yielding varieties, use of groundwater and chemical fertilizers in the Punjab, India has deteriorated the soil health and diminished water resources. Therefore for proper utilization of soil and water resources, it is necessary to diversify the on-going cropping system. But before that it is important to evaluate the soil chemical status of the area at regional scale which is lacking at this point of time. Keeping the following objectives in the mind, a block level study in the north-eastern agro-ecological sub region of Punjab is planned in which soil chemical properties were measured. The thematic maps of soil chemical properties – pH, EC, OC, CaCO₃, CEC and DTPA extractable available Cu, Zn, Fe, and Mn are prepared using GIS. More than 150 samples (0-15 cm) have been collected from different locations of the study area along with their longitude, latitude, and altitude using Global Positioning System (GPS). The results reveal that pH ranged from 6.9 to 8.9 with a mean value of 7.85 showing alkaline conditions. The EC varied from 0.09 to 1.3 dS m^-1 with a mean value of 0.21 dS m^-1. Organic carbon varied from 0.09 to 0.88 percent with a mean of 0.48 percent. Most soils of this area are only slightly calcareous with CaCO₃ ranging from 0 to 15.5 percent with a mean of 1.22 percent. CEC of the soils varied from 2.7 to 19.6 cmol kg^-1. DTPA extractable micronutrients were analyzed with the help of atomic absorption spectrophotometer. Available ZN, Cu, Fe and Mn content varied from 0.096 to 3.67 g kg^-1, 0.088 to 1.796 g kg^-1, 0.762 to 15.47 g kg^-1, and 0.608 to 10.55 g kg^-1. Comparison of available micronutrients with their critical limits, indicate that most of the samples are sufficient in micronutrients.