Managing Soils for Food Security and Climate Change

摘要

Four principal issues facing developing countries, such as India, are: (i) meeting food demand of the growing population, (ii) reducing risks of soil and ecosystem degradation, (iii) minimizing risks of eutrophication and contamination of natural waters, and (iv) decreasing net emissions of CO_2 and other greenhouse gases. A viable solution lies in a paradigm shift of not taking soils for granted. Soils must be improved, restored and used, rather than depleted, degraded and abused. Basic principles of soil management are: (i) creating a positive nutrient balance in agro-ecosystems, (ii) using crop residue, manure and other bio-solids as components of integrated nutrient management of enhancing nutrient-use efficiency, (iii) improving water-use efficiency, and (iv) reducing or eliminating plowing. Adoption of these measures requires a radical shift in the scientific, social, ethnic and cultural fabric of a society through developing alternatives to: (i) using dung as cooking fuel, (ii) crop residueas fodder, (iii) top soil for brick making, (iv) plowing for weed control, and (v) flood irrigation for improving soil-water regime. These practices, used for thousands of years, may have been sustainable when population was low. With large and increasing population, these extractive practices degrade natural resources, pollute the environment and change the climate. Establishing bio-fuel plantations on the village common land and degraded soils, using forage-based crop, rotations, making bricks from fly ash and other by-products, adopting no-till farming and using drip or sub-irrigation are high priorities that require serious and immediate attention of policy makers, land managers, farmers and the public at large. While improving agronomic productionand advancing food security, soil applications of dung, crop residue and other bio-solids have strong regional and global impacts on the carbon cycle, hydrologic balance, climate and drought, ecosystem restoration and quality of surface and ground waters.