Role of calcium carbonate minerals in improving sustainability of degraded cracking clay soils (sodic haplusterts) by improved management: an appraisal of results from the semi-arid zone of india

A long-term heritage experiment (LTHE) following the improved management (IM) system was initiated in 1976 on bench mark Vertisols (Kasireddipalli soils, Sodic Haplusterts with ESP > 5 but < 15 and saturated hydraulic conductivity, sHC < 10 mm hr−1) under semiarid tropics (SAT) environments at International Crops Research Institute for the Semi-Arid Tropics (ICRISAT) centre, Patancheru, India for increased productivity. It was undertaken to test the hypothesis that the IM system in combination with appropriate cropping practices can improve soil quality in comparison to the prevailing traditional management (TM) practices. The average grain yield of the IM system over thirty years was five times more than that in the TM system. Adaptation of the IM system improved physical, chemical and biological properties of soils to the extent that Sodic Haplusterts now qualify for Typic Haplusterts. Constant release of higher amount of Ca2+ ions during the dissolution of CaCO3 (8.4 mg/100g soil/year in 1m profile) under the IM system, compared to slower rate of formation of CaCO3 (0.10 mg/100g soil/year in 1m profile), provided soluble Ca2+ ions enough to replace unfavourable Na+ ions on the soil exchange sites. Higher exchangeable Ca/Mg ratio in soils under IM system improved the sHC for better storage and release of soil water during dry spell between rains. Adequate supply of soil water helped in better crop productivity and higher organic carbon (OC) sequestration. The improvement in Vertisols’ sustainability suggests that the IM system is capable of mitigating the adverse effect of climate change, and the sustainability of the Typic Haplusterts may continue for another couple of centuries under SAT environments, and thus stands for its adaptation on a sufficiently large scale through national and international initiatives