Potential of Spent Pleurotus ostreatus Mushroom Substrate as Compost

Oyster mushroom (Pleurotus ostreatus) cultivation produces waste in the form of mushroom substrate that has passed the production period and contaminated substrate. Non-productive spent mushroom substrates (SMS) still contain nutrients that allow them to be composted. The main goal of this study is to determine the potential of SMS as compost. The composting was done by mixing each of the old substrate waste (P1) and contaminated (P2) with a solution of EM4 and sugar. Temperature measurement and material compost stirring were done every week. The test results after 8 weeks of composting showed that the physical characteristics of compost, including the color and texture, have complied with the standards of SNI 19-7030-2004, which was brown and smooth. P1 compost has an earthy odor while P2 compost still has a slight woody. The mass of P1 and P2 composts decreased by 32% and 32,4%, respectively. Micronutrients such as Fe, Zn, and Mo were varied and according to SNI 19-7030-2004, Minister of Agriculture Regulations No.28/Permentan/SR.130/5/2009 as well as Minister of Agriculture Regulations No.70/Permentan/SR.140/10/2011. Co did not comply with the standard. The water content, pH, and macronutrients such as N-total, P2O5, K2O dan C-organic in both types of compost were according to SNI 19-7030-2004, Minister of Agriculture Regulations No.28/Permentan/SR.130/5/2009 or Minister of Agriculture Regulations No.70/Permentan/SR.140/10/2011. The C/N ratio in compost was still high, compost P1 and P2 had 25,26% and 25,16%. To reduce the C/N ratio of compost, it is necessary to carry out several treatments such as increasing the decomposition time or adding other organic materials during the composting process. The addition of organic materials such as manure or bran allows the microbial activators to be optimally in decomposing compost material to shorten the composting time.