Saturday, 15 July 2006

Role of Potato in Biologically Intensive Agriculture for Food Security and Management of Soil and Environment in Developing Countries.

J. P. Singh, Central Potato Research Station, Jalandhar, India and S.S. Lal, Central Potato Research Institute, Shimla, India.

Cereal based cropping systems particularly rice-wheat was adopted on large scale in developing countries since 1970, to meet the food requirement of growing population. Introduction of high yielding dwarf varieties of rice and wheat, increase in fertilizer and pesticide usage, extension of irrigation facilities were the main attributing factors. However, recent surveys and evidences from long term experiments have indicated stagnating or declining trend in productivity and profitability. Several constraints like ground water depletion, decline in soil organic matter and fertility, unbalanced fertilization in favor of nitrogen, micronutrient deficiencies, formation of hard pan in soil and increasing attack of pests particularly of the weed Phalaris minor have been identified to be responsible for the trend. Some environmental problems posing health hazards namely pollution of deep well drinking water with high level of NO3 caused by nitrogen fertilization and breathing diseases in rural and urban population due to smoke produced from burning of rice and wheat straw to quickly dispose the surplus have also been reported. Intensification of cereal based cropping systems with suitable crops with appropriate technology may help overcome these emerging problems, in developing countries particularly in South Asia where poverty is highly concentrated. Therefore, experiments were conducted during 1998-2005 to assess the potential of a short duration potato crop grown between the cereals and develop appropriate water, fertilizer and crop residue management technology to improve the productivity and profitability, soil fertility, conserve irrigation water and maintain clean environments. Intensification of rice-wheat cropping system by growing a short duration 85 days potato crop between the cereals increased the system productivity and profitability by 118 and 90%, respectively. The productivity in terms of Rice Equivalent Yield (REY) on price basis in intensified cropping system of rice-potato-late wheat was 24 t/ha/yr compared to only 11 t/ha/yr in traditional rice-wheat system. Irrigating rice crop after two days of disappearance of ponded water in field saved 25% of water without affecting the yield of rice crop. However, submergence was continued initially for two weeks till the establishment of the transplanted seedlings. Potato succeeding rice crop was found to be amenable to residue incorporation of rice straw up to 10 t/ha without any adverse effect of N immobilization on potato tuber yield. Dependence of early growth of potato on the mother tuber, late emergence of potato shoots requiring 13-16 days after planting and band placement of basal nitrogen helped potato to escape the lock in period of N for 21 days due to N immobilization in soil following residue incorporation of rice straw with wide C:N ratio. Potato haulms (2 t/ha) containing high level of N (2% DM) and narrow C:N ratio (21) was effectively incorporated in succeeding late wheat crop. Whereas, 5 t/ha of wheat straw could be incorporated in the transplanted rice crop without affecting the grain yield. A total of 12 t/ha of available crop residues (5 t/ha rice straw + 2 t/ha potato haulms + 5 t/ha wheat straw) were effectively incorporated into the soil in rice-potato-late wheat cropping system without affecting the yield of crops with improved soil organic matter and fertility. Fertilizer prescription equations for rice, potato and late wheat were developed using a modified linear model for site specific fertilizer management. Site specific management of fertilizer nutrients to each crop in rice-potato-late wheat based on soil test values increased the fertilizer use efficiency by 109% and reduced the fertilizer requirement by 48% compared to prevalent fertilization based on recommended package of practices for a large area on regional basis. Site specific fertilizer management increased the net returns and benefit:cost ratio on systems basis by 5 and 3.3%, respectively. It was concluded that biologically intensive cropping systems including potato combined with appropriate water and crop residue management and site specific management of fertilizer nutrients may improve the food security, ensure conservation of valuable soil and water resources and maintain pollution free environment by avoiding use of excess fertilization and burning of crop residues in developing countries.

Back to 4.2B Biologically Intensive Agriculture: an Approach to Combating Hunger for the Poor - Poster
Back to WCSS

Back to The 18th World Congress of Soil Science (July 9-15, 2006)