Enhanced composting of rice straw through amendment with Tithonia Diversifolia and cattle manure

Abstract

The Government of Rwanda has promoted rice production increasing the acreage by 3000 ha in the last decade. This has increased the quantities of straws in the field, which the farmers mainly burning or used a hedge and sometimes directly incorporated into the soil yet have high C/N ratio. The rice straws contains nutrient which can be recycled through composting. Therefore, a study was carried out at Kibaya-Cyunuzi rice experimental fields of Rwanda Agriculture Board to: (i) determine co-composting of rice straws with Tithonia diversifolia and cattle manure to enhance the composting process, (ii) to determine compost quality of co-composted rice straws with T. diversifolia and cattle manure for soil fertility management. The composting treatments were: (i) Rice straw alone, (ii) Rice straw + T. diversifolia, (iii) Rice straw + Cattle manure and (iv) Rice straw + T. diversifolia + cattle manure. Organic carbon significantly (p < 0.001) decreased during composting as total N increased. Composting with T. diversifolia reduced the C/N to less 12 within three and by the fifth week when cattle manure was used. However, these maintained thermophilic temperatures indicating matured but unstable compost. Stable compost was realised in the 13th week when the WSC and temperatures dropped to the most minimum. At maturity, composting rice straw with Tithonia diversifolia had a consistently highest concentration of N and P followed by a co-compost of cattle manure. It was therefore concluded that co-composting with Tithonia diversifolia enhanced rice straw composting and produced high quality compost earlier than cattle manure.