Saturday, 15 July 2006

Maturity and stability parameters of composts prepared from farm wastes.

Devraj Chauhan, V.S. MOR, and C.P. SINGH. CCS, HAU, HISAR,HARYANA, Hisar, India

Composts were prepared from different farm wastes for fixing the maturity/stability indices. Different farm wastes such as chopped mustard straw, paddy straw, pearl millet boobla (Flower glumes and rachilla) and cattle dung mixed thoroughly in the ratio of 4:1:1:2 respectively. Five composts such as mixed farm waste (MFW), MFW+N, MFW+N+MRP, MFW+MRP+MO and MFW+N+MRP+MO were prepared from these wastes. One Kg MRP (Mussori Rock Phosphate) was mixed in to 4 Kg of farm wastes and kept in polythene bags. Moisture of composting material was maintained at 70% on dry weight basis. All polythene bags containing different compost mixtures were placed in a pit (6x2x1m size) and pit was covered with polythene sheet along with 5 cm soil layer over it. A homogenous representative sample was drawn from each bag at 0, 15, 30, 60, 90, 120 and 150 days for determining different characteristics. Temperature of composting materials was measured on daily basis by thermometer. All the composts attain maximum temperature between 4-6 days and after that temperature decreased gradually but remain in thermophlic range upto 61 to 68 days. It was further decreased and approached to ambient level between 101 to 115th day of composting. After 120 day, all the composts attained a constant temperature with no measurable changes and equal to ambient temperature indicating stable nature of composting process. Daily observation of temperature is vary necessary to monitor the condition of composting process. Enrichment of Nitrogen, MRP, and Microorganism increased the loss of organic matter, which results shorten the time of composting and improves the quality of composts by increasing total nitrogen content from 1.31 to 1.7%. Constant value of pH, EC, water soluble carbon and total organic carbon of MFW+N+MRP and MFW+N+MRP+MO composts shows their stable nature. Based on the results of the present investigation following maturity indices found to have best correlation with a large number characteristics and have been established: organic matter loss >42%, C: N ratio <15, Cw/N org. <0.55, HA/FA ratio <1.90, HI>30% and CEC/TOC<1.7. Water-soluble organic carbon content <1.7%, NH4 content <0.04% and CEC>60 meq/100 (on ash free material basis) were not found suitable criteria for judging maturity/stability of composts prepared from different farm wastes.

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