Improving Saline-Alkali Soil with Agricultural Waste in China: A Review

A large amount of agricultural waste is produced annually in China, and these agricultural wastes include crop residues and the manure generated from poultry and livestock farming. But there is still a considerable portion of agricultural waste that is not recycled and disposed of or directly burned. Therefore, if these agricultural wastes can be reasonably utilized, it will generate significant socio-economic and environmental benefits. Soil salinization has become one of the main threats to soil health, and agricultural waste is considered an effective tool for improving saline alkali land due to its unique properties. Utilizing agricultural waste to improve saline alkali land has advantages such as wide material sources, low cost, and low environmental risks. This article reviews the effectiveness and potential physical, chemical, and biological mechanisms of agricultural waste in improving soil health in saline alkali soils. Agricultural waste is mainly used to improve saline alkali land through a direct return to the field, burial of salt barriers, pyrolysis and carbonization into biochar, and composting, which can play a positive role in physical, chemical, and biological aspects. Finally, the problems existing in the improvement of saline alkali land with agricultural waste were discussed, and future research directions and hotspots in this field were proposed. It is believed that the improvement of ecological service functions is the key to its sustainability. This article can provide a theoretical basis for the study of agricultural waste in the improvement of saline alkali land, and help to further explore the resource utilization pathways of agricultural waste in sustainable agriculture.