4. Review-EFFECT OF ORGANIC MANURE ON RICE-WHEAT CROPPING SYSTEM by MANISHA SAHU, DR. AJAY VERMA AND DR. V.M. VICTOR
The importance of organic manures and fertilizers in the maintenance and improvement of soil productivity particularly under intensive cultivation. Organic manures are the valuable byproducts of farming and allied industries derived from plant and animal resources. These organic manures being slow in release of nutrients, assume greater significance in a cropping sequence than individual crops and their usefulness needs to be investigated on long term basis. In this context, available literature in respect of nutrient content, effect of composting, effect of application of organic manure on soil properties, yield and quality of crops and residual effects are reviewed in this paper. The continuous depletion of nutrients due to intensive cropping system is posing a serious threat to sustainable agriculture. At the same time, the farmers cannot afford to supply all the essential nutrients through chemical fertilizers. Organic sources of the nutrients although in small quantities, can solve the problem to some extent and help to conserve soil health. It is widely recognized that neither organic manures nor chemical fertilizers used separately can achieve the yield sustainability at a higher order under the modern intensive farming, in which the nutrient turnover in the soil-plant system has been quite high. Integrated plant nutrient supply system involving conjunctive use of chemical fertilizers and organics assume great significance particularly in rice-wheat cropping system mainly due to two reasons. First, the system requires the application of higher amounts of nutrients than used at present and the present level of fertilizer availability and economic conditions of large number of Indian farmers do not allow this. Secondly, it leads to soil health deterioration because of high nutrient requirement. Several studies have also indicated that in intensive cropping systems the sustainability could be achieved only through integration of inorganic and organic sources of nutrients. But in future, it is needed to conducting experimental research on rice-wheat cropping system with organic fertilizer only.
KEY WORDS: Rice-Wheat Cropping, Organic Manure, Chemical Fertilizer.