CIRCULAR AGRICULTURE RECYCLING ORGANIC WASTES FOR SOIL FERTILITY AND SUSTAINABLE CROP PRODUCTION: A REVIEW

Abstract

The growing pressure on agricultural land to produce food, feed, fibre and industrial raw materials has led to an intensive use of soil, water, fertilizers and other external inputs. Because of continuous cultivation, unbalanced fertilization, the burning of crop residues, a decline in soil organic matter and the improper management of agricultural and food-processing wastes, serious problems have arisen for the sustainability of present-day agricultural systems. At the same time, large amounts of crop residues, livestock manure, poultry litter, wastes from fruit and vegetables, by-products from food processing and other biodegradable materials are produced each year. These materials contain large amounts of organic carbon and essential plant nutrients and so can be turned from waste into valuable resources by means of circular agricultural practices. Circular agriculture offers a resource-efficient approach in which nutrients, carbon, water and energy are recovered and re-introduced into productive systems rather than being lost through disposal. By recycling organic wastes through methods such as composting, vermicomposting, anaerobic digestion, biochar production, incorporating residues, managing manure and using an integrated system of organic and mineral nutrients, it is possible to improve the physical, chemical and biological characteristics of the soil and to help achieve sustainable crop production. Organic amendments can raise the level of soil organic carbon, enhance aggregate stability, increase the cation exchange capacity, improve the water-holding capacity, boost microbial biomass and make nutrients more available. They can also reduce the need for synthetic fertilizers, cut down on residue burning, improve nutrient-use efficiency and help with soil carbon sequestration. Yet, the uncontrolled application of untreated organic wastes can result in environmental and food-safety risks due to pathogens, heavy metals, salinity, losses of nutrients, emissions of greenhouse gases, microplastics and emerging contaminants. As a result, effective circular agriculture depends on source segregation, proper treatment, quality assessment, application based on nutrient content, monitoring and life-cycle evaluation. This review examines the principles of circular agriculture, the main organic-waste resources, the recycling technologies, the effects on soil fertility and crop productivity, carbon sequestration, environmental implications, risks, economic opportunities, technological advances and future research needs. The review concludes that scientifically managed recycling of organic wastes can play a major role in building resilient, resource-efficient and environmentally sustainable agricultural systems.