Improvement in soil fertility under long-term intensive irrigated agriculture Punjab (North-west India) scenario

Abstract

Aim: The objective of this study was to monitor the changes in soil fertility parameters of Punjab soils for the last 15 years (2005/06 to 2019/20) and to estimate the contribution of rice-wheat system to soil carbon sequestration. Methodology: This investigation is based on 66.7 thousand surface (0-15 cm) soil samples that were received in the Soil Testing Laboratory, Department of Soil Science and were analyzed for different fertility parameters such as pH, EC, organic carbon, phosphorous and potassium following standard protocols. Results: Analysis of soil fertility parameters data of last 15 years indicated positive trends of change in soil pH (7.7 to 7.4), organic carbon (4.0 to 5.4 g kg-1) and available P (9.9 to 15.4 mg kg-1). These changes are very much synchronised with increase in average rice-wheat yield trend (7.99 to 9.38 t ha-1) in the State of Punjab. Intensive cultivation also helped in higher soil carbon sequestration (3.73 t ha-1). Interpretation: There is an indication of improved soil fertility/health, including increased soil carbon sequestration in the Indian Punjab. The long-term trends of change in different soil fertility parameters will help to regulate the fertilizers usage to sustain the soil health as well as crop yields in this region. Key words: Intensive agriculture, Punjab, Rice-wheat cropping system, Soil organic carbon, Soil pH