Application of agro-waste compositional data to predict composting efficiency

A.R. Mohammad Hariz, H.K. Ong, A.B. Nurul Ain and J. Fauzi

Abstract

Composting is one of the effective approaches for reducing the amount of disposed organic waste and produces value added products to optimise its use for agriculture. In order to improve compost quality and efficacy, the use of agricultural wastes compositional data can be an effective tool to improve efficiency, especially in estimating the initial C/N ratio of the composts and predicting the final compost quality. In this study, characterisation on 25 types of local agricultural wastes was conducted to determine the basic chemical characteristics of the waste materials. Data from the samples were ultimately used as reference to determine and formulate basic material combinations for compost. The compositional data of these common agro-wastes are usable for formulating nutritionally ideal mixtures of composts. A field study on composting of a mixture of baled rice straw and goat manure (weight ratio of 1:1 for straw:manure) was conducted to determine changes in C/N ratio from initial composting to the final products. During the 8 weeks composting process, the total C/N losses were found to be between 43.7 and 67.6%. The compost reached a C/N ratio of 10:1 after 2 weeks. The optimum temperature ranged from 55 to 60 °C within the first 2 weeks of composting and leveled off below 40 °C after 38 days. The study confirmed that the process of achieving matured compost can be optimised if ideal combinations of initial C/N ratio were used.

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