Application of distillery effluents to agricultural land: is it a win-win option for soils and environment

Molasses based distilleries in India generate approximately 40 billion litres of effluents annually characterised by high organic load and salts posing a major disposal problem. The post methanation distillery effluent (PME) also being rich in plant nutrients (K, N), its use as ferti-irrigation source in agriculture is an attractive disposal option. The paper discusses the experimental results of effects of PME application (treatments: 0, 10, 20, 30 and 40 per cent of PME (5000 mg/l)) in agricultural field on the soil microbial population and chloride levels; thereby know whether soil is a good sink for recycling this nutrient rich effluent. Microbial enumeration studies revealed a beneficial effect of PME irrigation up to 30 per cent concentration due to the presence of carbon and nutrients that enhanced the soil microbial activity. Soil chloride levels and effluent colour were highest in the 0-30 cm soil depth, and beyond 45 cm their concentration decreased significantly suggesting soil acted as a good medium. Crop growth and soil health were negatively affected at higher PME concentrations or when applied without dilution. Therefore, monitoring and integrated approaches are needed to effectively utilize PME as valuable resource in agriculture and reduce its negative effects on the environment