Comparison of arbuscular mycorrhizal fungal spore population and total microbial count in farmer's fields with various crop residue practices

摘要

Rice and wheat are the two major crops in the IGP (Indo-Gangetic Plains) of South Asia comprising Bangladesh, India, Nepal, and Pakistan. The R-W (rice-wheat) systems represent 32% of the total rice area, and 42% of the wheat area in these countries (Ladha, Fischer, Hossain, et al. 2000). The importance of intensively cultivated R-W systems is fundamental for generating employment, income, and livelihoods for hundreds of millions of rural and uiban population in South Asia. To improve the crop yield,farmers have been practising intensively irrigated R-W systems over the past couple of decades. A slow growth of productivity in agriculture and negative impacts of intensive agriculture on environmental quality suggested the infusion of a complimentaryset of new agricultural technologies to boost productivity. Zero tillage and reduced tillage are such technologies recommended by the RWC (Rice-Wheat Consortium) and CIMMYT (International Maize and Wheat Improvement Centre) to sustain and enhance productivity of the R-W system at a reduced cost of production (Gupta, Hobbs, Ladha, et al. 2002). One of the newly emerging issues under increasing mechanization in the R-W areas is the management of straw after combiner harvesting of rice. As wheat is increasingly planted under zero tillage, it is imperative for farmers to remove rice straw and stubble without ploughing, and do this as fast as possible for the timely seeding of wheat. A large number of farmers in the high production area of the northern IGPare burning straw, which not only results in loss of organic matter, but also causes serious environmental problems. The present study was conducted to compare the AM (arbuscular mycorrhizal) fungal populations in two categories of zero-tilled fields: (? residue was incorporated in the field, and (2) residue was burned.