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Composting[Also see the Soil section in BHU information pages for experiments and articles related to composting] Below is a table of C:N ratios and other relevant data for working out desirable mixtures of compost material. Composting is very forgiving and sawdust by itself eventually rots after several years and lawn clippings by themselves although causing smell and fly problems will turn into first something a bit like very poor silage and eventually humus. Of course we want to have something in between. Too much nitrogen leads to potential anaerobic (lack of oxygen) conditions, odour problems and loss of nitrogen. Too little nitrogen causes a slower than needed process and can mean insufficient heat to kill weeds and weed seeds and to control plant diseases. Too much compacted material such as grass clippings can cause anaerobic conditions and odour problems. Too loose a compost may slow the composting and mean insufficient heat. This can be overcome to some extent by compacting the material while building the heap. Use the table below to help balance out ingredients for your compost heap. For an efficient heap the aim is for an overall C:N ratio of 25 to 30 (30 is the balance that most microorganisms have between carbon for energy and nitrogen for protein - 25 makes for a better functioning heap). To work out the combined C:N ratio, use the average of the C:N ratios e.g. 5 parts dairy manure to 1 part wheat straw = (13 X 5 + 125)/6 = 32 which is close to ideal. REMEMBER C:N RATIOS ARE BY WEIGHT SO THE PARTS ARE BY WEIGHT - TO CONVERT TO VOLUME MEASURE SOME OUT OR USE THE ROUGH GUIDES BELOW. NO NEED TO BE EXACT, BELOW ARE JUST ROUGH GUIDES AND COMPOSTING IS FORGIVING (though commercial compost needs to be a bit more fastidious)
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