Dynamics of Soil Fertility in Organic Farming Studies of Maize - Sunflower - Green Gram Cropping System

Field experiments were conducted for two consecutive years (2003-04 and 2004-2005) at S.V. Agricultural College Farm (ANGRAU), Tirupati , Southern plateau and Hills zone of India on red sandy soils consisting Greengram was raised as residual crop during summer in a sequence of Maize sown in Kharif and Sunflower sown in Rabi with the imposition of the treatments to the first two crops of the sequence. There were fourteen treatments comprising of six different sources of nitrogen viz., farm yard manure, vermicompost, neem leaf manure, poultry manure, pig manure and fertilizer to supply recommended dose of nitrogen on equalent nitrogen basis and one absolute control. All the seven treatments were tried with and without the foliar application of Panchagavya, thus making the total treatments to fourteen. Regarding the dynamics of various soil fertility parameters viz., soil organic carbon, available nitrogen, available phosphorus and available potassium, all of them were found built up to a considerable extent with the use of organic manures to maize and sunflower, while the application of fertilizer to maize and sunflower could just maintain the soil fertility status with neither considerable replenishment nor deterioration.As regards the balance sheet of soil available N, P and K, the highest positive balance of soil available nitrogen was found associated with neem leaf manure, and that of phosphorus was associated with poultry manure while that of potassium was with vermicompost. However, all the organic manures could result in higher balance than with application of fertilizer to maize and sunflower crops. Irrespective of the manurial sources, use of Panchagavya did not exert any noticeable effect on fertility enrichment of the soil.