Mapping of Chemical Characteristics and Fertility Status of Intensively Cultivated Soils of Punjab, India

Cultivation of high-yielding crop varieties and intensive cropping has depleted the soil fertility in Northwest (NW) India, resulting in the appearance of multi-nutrient deficiencies in different crops and cropping systems. In the present investigation, geo-referenced soil samples from Indian Punjab were analyzed to map fertility status using a Geographical Information System (GIS). Soil texture, which affects soil hydraulic properties and soil strength, varied from sandy to clayey loam, with majority (47.3%) of the cultivated area being sandy loam. About 95% of the total area of the state shows pH between 6.5 and 8.5 (40% of the area between pH 6.5 and 7.5 and 54% between 7.5 and 8.5) and electrical conductivity (EC) <0.8dSm(-1). Calcium carbonate (CaCO3) with <5% values represents 97% area of the state. The GIS-based maps indicate that irrespective of the agroclimatic variations, more than 90% of the soils showed low to medium soil organic carbon (OC) content and 50% low to medium (<22.4kgPha(-1)) available phosphorus (P) content with a marginal (7%) deficiency of potassium (K). The dominance of low to medium status of available P in these soils could be due to the mining of soil P by the rice-wheat cropping system practiced in the region. The intensively cultivated soils of Indian Punjab showed 11% of soil samples were low in zinc (Zn), 15% low in manganese (Mn), 2% low in copper (Cu), and 12% low in iron (Fe). Availability of micronutrients increased with increase in OC content and decreased with increase in sand content, pH, and CaCO3. GIS-based maps are effective in identifying hot spots, which need immediate attention and call for strategic planning for sustainable management.