Original Articles

Changes in chemical properties and temperature during the degradation of organic wastes subjected to simple composting protocols suitable for small-scale farming, and quality of the mature compost


Abstract

Despite the high cost of chemical fertilizers and pesticides, composting is not widely practiced in many rural communities in South Africa. To demonstrate the simplicity and benefit of composting, four composting protocols were selected, based on technology and resources available to rural households and small-scale farmers, and their effect on the degrading material and on the quality and yield of the resulting compost was investigated. The protocols varied in raw material choice (garden refuse with and without market refuse) and turning frequency (6×, 0×). Changes in chemical properties during composting were in accordance with those generally observed and were alternately affected by raw material and turning frequency. The highest temperature measured in compost made from market and garden refuse was 69°C whereas in compost made purely from garden refuse the highest temperature was 53°C. Turned compost heaps yielded the highest volumes of mature compost. All composting protocols produced composts with C/N ratios and pH values suitable for horticultural use. Nutrient concentrations were in the range generally exhibited by composts. The incorporation of market refuse and the turning were conducive to the production of a nutrient-rich compost. However, turning also significantly increased the electrical conductivity of the composts and application rates should be reduced accordingly when turned compost is used for crops with a low resistance to osmotic stress.

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