Studies On Composting Technology Of Sawdust And Rice Husk As Media

Nowadays, there is a trend in manufacture of organic media to have with merits of environmentally-friendly, economic, intensive and physically-and-chemically-good properties. The organic media has become the most widely used soil-free cultivation method. The organic waste will be the main choice of future media material because of the fine properties, such as coconut husk, rice husk,sawdusk and peanut husk. But for the low stability and poisonous as plant seed substances in it, the organic waste can't be use as organic media directly certain decompsting processes. At present, the method to turn organic waste into high quality organic media was composting, the essence of which is the process of decomposing solid waste into relatively-steady humus. This study was based on the technology of aerobic at high temperature composting.Rice husk and sawdust are chosen as main materials in this study of composting of organic waste into media. The goal of this research was to discover the best fermentation device, which can be used to regulate the composting factors, and find out the best nitrogen source for sawdust and rice husk composting, and microbial inoculum type and recruitment. The fllowing are the results of this study:(1) There is no correlation between the room temperatureand the temperature changes in phases of wanning, high-temperature and cooling in the process of composting. The room temperature 15℃was the start point for microbial to begin decomposting. The appropriate temperature of organic waste composting as media is 45℃～55℃.(2) Physical and chemical properties are improved, specifically as follows: increase in bulk density, enlarging of general porosity and capillary porosity, augment in CEC and the water-air ratio. For the original poor water-holding performance, it's difficult for seedlings to maintain water during growing, but it's improved greatly after decomposition.(3) There was a decline in total carbon and C/N value while the total nitrogen of the same media content goes through a climbing-up trend. Most of organic matter is decomposed and T value of better composting treatments falls down to below 0.5; Cellulose decomposition rate is more than 30%, soluble sugar decomposition rate is over 50%. (4) When studied on microbial inoculum, we discovered that the treatment of adding enzyme bacteria could warm up to the highest temperature more quickly and adding EM bacteria seemed to work slower, the highest temperature of which was higher than that in treatments of adding enzyme bacteria and fermentation bacteria. The best dose of adding microbial inoculum in the decomposition of organic waste is 1% of the total. The overall evaluation index, showed that the discrepancy of influence on composting and growing seedlings by using different types of microbial inoculum was not significant, and composting process can be accelerated as long as the sufficient bacterium.(5) The organic nitrogen sources like chicken manure are more beneficial to rice husk and sawdusk composting than inorganic material, since the added chicken manure could make media speed up fermentation at a higher temperature. (NH₄)₂SO₄ worked best among all kinds of inorganic nitrogen sources tried. Adding SSP in the amount of 1% of the total could improve the seedlings growing.(6) The treatment with the combination of sawdusk and rice husk worked better than the treatment of single ingredient during the composting. From the cultivation experiment in nursery after composting, treatments of T5 and T2 had the best response of seedling quality, of which the proportion of sawdusk and rice husk are 8:2 and 2:8 respectively. From this, we can draw a clear conclusion that the combination of sawdusk and rice husk after conmposting can be used media as high quality organic and put into nursery of production.