Professor Biswapati Mandal1, Dr Asihm Datta2
1Department of Agricultural Chemistry and Soil Science, Bidhan Chandra Krishi Viswavidyalaya, Mohanpur, Nadia, India, 2ICAR-Central Soil Salinity Research Institute, Karnal, India
Rice (Oryza sativa L) is the foundation of global food security particularly in Asian countries. In India only, about 43 million ha of land is under rice cultivation as a mono-crop, rice double crop, and other rice-based cropping systems. Among these, submerged puddled rice is the most common. For maintenance of soil health and curbing global warming, it is important to unveil the processes of accumulation or depletion of organic carbon in soils (SOC) under different management practices of paddy-rice. An attempt is, therefore, made to study the impact of long-term intensive paddy-rice systems with different management practices on the SOC stock in a few long-term fertility experiments under subtropical climate. The mechanistic pathway of stabilization of the SOC into different pools with a tentative C budgeting was also established. Biochemical composition of the organic residues involved, SOC pools of different oxidizability and carbon accumulation from other sources were estimated for the experiments raised with different organic and inorganic sources of nutrients. Cultivation over the years caused a net decrease in SOC stocks, but with balanced fertilization it increased. With increasing depth, the stock decreased on average, to the extent of 50%, 26% and 24% of the total at 0-0.2, 0.2-0.4 and 0.4-0.6 m, respectively. About 4.0% of the crop residues C incorporated into the soil were stabilized into SOC. This was further enhanced (~1.5 times) by the application of organics. Again, a good part (~15%) of the carbon added through organics was stabilized into SOC mostly in the recalcitrant pools; the amount, however, varied among the sources used maximum with farm yard manure. Results thus indicated that paddy-rice system is a good sink for SOC sequestration besides its role in maintaining soil health and providing food security.
Keywords: Rice–rice ecology, carbon stabilization, crop residues, soil C-pools
Biography: Professor Biswapati Mandal is a senior professor in State Agricultural University working on organic carbon management in soils with a group of graduate, postgraduate and postdoc students for more than the last 20 years.