Sustainable approaches towards organic matter management and intensification in coffee soils of Ethiopia-some suggestions

Agricultural-based Ethiopian economy is highly dependent on Coffea arabica L. as it constitutes more than 60 percent of the foreign exchange earnings and provides means of livelihood to over 15 million people. The Ethiopian coffee culture is predominant in the southern, south-western and south-eastern parts. Also known as highland coffee culture on Inceptisols, Alfisols and Oxisols, it is under a fragile ecosystem. These soils of coffee culture are characterised by inherently low nutrient status, low base saturation, low cation exchange capacity, increased bulk density, concomitant reduction in porosity and water infiltration leading to accelerated erosion. These soils tend to become infertile with consequential crop productivity losses, if practices to promote accumulation of humus are not encouraged. In the given situation, one of the suggested viable approaches is to promote organic intensification through biorecycling of locally available cheaper organic wastes which are both eco-friendly as well as sustainable besides strengthening Ethiopia's position in the world coffee trade as producer of 'organic' coffee. In this context, abundantly available organic source materials as coffee cherry husk, pulp, parchment which are coffee processing byproducts could be gainfully utilized which are currently being dumped as wasts with considerable impact on environment. The approach involves treating the lignin and cellulose coffee wastes in heaps with 1% urea or with the nitrogen-rich organic substances like green leaves (Erythrina, crotalaria etc.) or cakes of different kinds and adjusting the moisture content to 60-80 percent. To this, sources of lignocellulose decomposing micro-organisms like farmyard manure or compost, fresh cow-dung, garden soil, forest soil etc., at 5-10% on weight basis are added layer by layer to facilitate faster decomposition. Frequent turnings to provide adequate aeration at fortnightly intervals with moisture adjustments and dressings of cow-dung slurry is essential. In the field, heaps of size 3.0x1.5x1.0 m tapering towards the top were found optimum. In this method, coffee compost was ready in about 3-4 months which, on application to plantations at 10-15 tonnes per hectare, would be sustainable. The coffee compost could also serve as an ideal substrate for mass-multiplication of fungal antagonists, Trichoderma, Gliocladium spp. used as effective biocontrol agents for management of various soil-borne diseases different horticultural and plantation crops. The present paper describes the detailed methodology of recycling coffee wastes and their production of biocontrol agents.