Abstract:

As a disturbance to soil ecosystem, organic mulching has a significant impact on soil structure and function, which plays an important role in urban soil conservation and urban soil restoration. The effects of organic mulching on soil environment were discussed, and its mechanisms were further clarified based on a literature review from Web of Science, CNKI, and other databases. It is important to further exploring the substance cycling process of soil ecosystem and improving the technical system of application of organic mulch, as well as strengthening the effects of urban soil conservation and restoration. Most studies illustrated that organic mulching could alleviate evaporation of surface water and direct infiltration of rainwater, promote soil aggregate structure, improve soil water retention, help to stabilize soil moisture and slow down soil erosion. Organic mulching cools the soil at high temperatures but keeps it warm at lower temperatures, which improves the conditions of plant growth. The greenhouse gas emission is uncertain because of the influences of soil conditions, mulching amount, mulching materials, and other factors. Due to the changes of soil water, air and heat, the activity, species and diversity of soil microorganisms after organic mulching are affected, and the activities of soil animals are also stimulated, which improves the soil structure and quality. The improvement of soil physical and chemical properties, the increase of nutrients and the changes of microbial community structure and function further enhance soil enzyme activity and accelerate the transformation rate of carbon and nitrogen in soil. Affected by the soil environment, the structure of plant root system was changed, fine root turnover was strengthened and rhizodeposition was increased. Additionally, the organic mulch itself provides the soil with carbon source, the substance cycle of soil ecosystem is accelerated, which causes the increasing sequestration of soil organic carbon, while the changes of soil carbon fractions remain contested. The decomposition of organic mulch increase soil organic matter and nutrient content, improve soil nutrition and increase soil fertility to varying degrees. At present, there are more and more studies on organic mulching on soil environment, however, the results have not been uniform, there is a lack of long-term in situ monitoring data, its mechanism has not been clearly understood, and the technical system in production practice still needs to be improved. Therefore, suggestions are put forward for future studies:1) Long-term dynamic monitoring and experimental studies should be carried out to clarify the changes of soil environment after organic mulching. 2) Comprehensively explore the effects of organic mulching on the transportation process of substance and energy in soil ecosystem, and deepen the understanding of the mechanism of the impacts. 3) Establish a sound technical system for organic mulch application to improve soil conservation and soil remediation effects.

Key words: organic mulching, soil environment, carbon and nitrogen cycles, soil fertility