Agronomic application of food processing industrial sludge to improve soil quality and crop productivity

Abstract Sludge, a by-product of wastewater treatment processes, is an alternative to conventional means of disposal and increasingly applied to agricultural lands as a source of fertilizer. In the present work, sludge generated from food processing industry was applied to agricultural soil as a conditioner and its effect on physio-chemical properties of the soil and crop productivity were studied. The industrial sludge was amended in different proportion (10–50 t/ha) with soil and the feasibility of these amendments were studied. The results revealed that application of sludge to soil increased its pH, EC, CEC and other nutrients such as organic matter and phosphorous. A reduction in the soil nutrients (nitrogen and potassium) in post-harvest soil indicates their uptake from soil by the plant and thus, productivity increases. No indication/evidence of harmful effects of heavy metals from sludge on quality of soil and cultivated product was found, when the amendment was controlled within the range of 50 t/ha for both dry and wet sludge applied. However, deterioration in the growth rate was observed beyond 30 t/ha amendment due to the excess organic and nutrient load accumulated in the soil. The effect of bio-fertilizer and chemical fertilizer to support the crop productivity were also studied. Thus, food processing industrial sludge application positively affects crop productivity and significantly improves soil quality. Still, much is to be learnt from this study and the present investigation needs to be continued to determine whether the agricultural objectives are satisfied in longer term.