RECYCLING - SMS

Compost is considered "spent" when one full crop of mushroom, has been taken or when further extension of cropping becomes unremunerative. Unplanned release of spent mushroom substrate (SMS) creates various environmental problems including ground water contamination and nuisance. However, if handled properly it can be used for managing agriculture, environment and to produce recyclable energy. Fresh SMS contains 1.9-0.4-2.4% (N-P-K), while 8-16 months old contains 1.9-0.6-1.0 (N.P.K). SMS does not fall in the category of hazardous substances as it does not contain heavy metals. SMS obtained from various sources vary in its physical and chemical properties.

The material has been found to be good nutrient sources for agriculture. Its addition in nutrient poor soil leads to an improvement in soil texture, water holding capacity and nutrient status. The phosphorus and potassium requirements of the crop plants can be fulfilled by incorporating 5% of SMS by volume, while nitrogen requirement can be fully met by 25% of SMS by volume. The microbes inhabiting the compost exert antagonism to soil pathogens thus protect the plants from diseases.

Treatments like rapid salt leaching and recomposting by aerobic or anaerobic methods for one to two years make SMS more suitable for growing flowers, vegetables, fruit, saplings, ornamental shrubs and other horticulture plants of economic importance. The SMS acts as a good growing medium for vegetables like cucumber, tomato, broccoli, tulip, cauliflower, peppers, spinach etc. The incorporation of 12-18 months old aerobically/anaerobically recomposted SMS in field led to enhanced yield and quality of Tomato, Shimla Mirch, Pea, Cauliflower, Ginger, Onion, Brinjal and Wheat along with lower incidence of disease and insect pests
The use of anaerobically recomposted spent mushroom substrate as casing material gave superior button mushroom yield with better diseases management.

SMS adsorbs the organic and inorganic pollutants and biodegrade them in non toxic forms thus help in reclamation of chemically contaminated soils.

SMS of paddy straw, oyster and button mushrooms can be used as feeding material for vermicomposting.