An appraisal of organic and inorganic carbon contents in post-harvest soils of rice based sequential cropping systems influenced by rice cultivation methods and nutrient management practices
1S. Swathi, 2*C. Ravikumar, 3M. Thiruppathi and 4P. Senthilvalavan
1,2,3Department of Agronomy, Faculty of Agriculture, Annamalai University, Annamalainagar-608002 (India) 4Department of Soil Science and Agricultural Chemistry, Faculty of Agriculture, Annamalai University, Annamalainagar-608002 (India) *Corresponding author E- mail: ravikumarchinnathambi@gmail.com
ABSTRACT
Carbon is the primary source in plant nutrient system thus crop growth and yields are basically influenced by soil carbon status. Contraption and contents of soil organic and inorganic carbon play an important role in carbon status. Several studies reported on soil organic carbon {SOC} but not soil inorganic carbon {SIC} “the missing sink” of carbon pool. Also, reports on the impact of cultivation and nutrient management practices under different rice based cropping system for SOC and SIC are very meagre. To investigate these carbon details, field experiments were conducted during September to May in 2021-2022 and 2022 -2023 under rice based sequential cropping system {rice-black gram, rice-maize and rice-groundnut} and evaluate how cultivation methods and integrated nutrient management {INM} practices influences the carbon contents in soils for two years. Experiment designed with two establishment methods {transplanted method {TPR} and direct seeded method {DSR}} and five INM practices {RDF {NPK} only, RDF + poultry manure compost @5 t ha-1, RDF + coirpith compost @5 t ha-1, RDF+green manure @6.25 t ha-1 and RDF+green leaf manure @ 6.25 t ha-1}. The nutrient treatments were imposed only to rice crop and no manures/ fertilisers applied to sequential crops. INM practice of RDF + green manure @ 6.25 t ha-1 imposed under direct seeded rice cultivation method registered higher SOC {8.68 and 8.96g kg-1} and total carbon {11.83 and 12.41 g kg-1}, for season I and season II, respectively and it was statistically on par with RDF+ green leaf manure @ 6.25 t ha-1 in ricegroundnut cropping system. Further, we observed that there is no significant improvement in soil inorganic carbon content. However, slight changes occur in SIC compared to initial status after rice cultivation but no changes due to cultivation of sequential crops