Evaluation of hydrothermal treatment in enhancing rice straw compost stability and maturity

Abstract

In order to evaluate the hydrothermal treatment (HTT) in enhancing compost stability and maturity of lignocellulosic agricultural residues, a bin-scale (90 L) composting of rice straw with and without "HTT" was performed. The rice straw compost product with "HTT" after 6 weeks of composting can be considered stable and adequate for field application as expressed by pH of 8.4, "EC value" of 2.96 dS m(-1), C/N ratio of 12.5, microbial activity of <8.05 mg CO2 g(-1) OM d(-1), NH4(+)-N content of 93.75 mg kg(-1) DM and finally, by "GI" of >83%. However, compost may prove phytotoxic if used as growing media for EC sensitive plants. As for rice straw compost product without "HTT", the high microbial activity (>12.28 mg CO2 g(-1) OM d(-1)) even after 14 weeks of composting suggests that the residue has not stabilized yet and is far away from stability and maturity, although a higher GI (>100%) was observed.

Keywords: Compost; Hydrothermal treatment; Rice straw; Stability and maturity.