Biodegraded cocopeat as a horticultural substrate

Cocopeat or coir dust is a by-product separated during processing of coconut (Cocos nucifera L.) coir. As a by-product of coir manufacturing, cocopeat is often unutilized or burnt in the open. Of late, due to environmental concerns and also diminishing supplies of peat soils for horticultural substrates, cocopeat is being considered as a renewable peat substitute for use in horticulture. However, in its raw form, cocopeat has been reported to contain phytotoxic elements which inhibit plant growth. As such, cocopeat is often recommended for use only with a mixture of other organic or inert materials. The present study was conducted to determine the effect of biodegradation (composting) on improving the qualities of cocopeat as a horticultural substrate. Cocopeat was supplemented with 0.75% N and inoculated with selected mould and wood rotting micro-fungi viz. Aspergillus niger van Tieghem, Penicillium citrinum Thom, Trichoderma sp., Humicola sp. and Chaetomium globosum Kunze. The medium was maintained at about 80% moisture content (wet weight basis) and incubated at 27°C for 3 months. The results showed that the 3-month biodegraded cocopeat has lower C/N ratio, higher CEC and humic acid than the raw cocopeat. The lowering of C/N ratio was due to addition of N and the reduction of carbon, mainly the hemicellulose, cellulose and to a lesser extent the lignin components. In the greenhouse trial, tomato plants grew well in the 3-month 'composted' cocopeat. Though their plant heights and stem diameters were not significantly different from those grown in the untreated cocopeat, the plants on 'composted' cocopeat produced higher dry root weights (22%), fruit numbers (43%) and total yield (64%)