Preparation of two types plant biochars and application in soil quality improvement

Soil degradation is a global problem that endangers sustainable development. Biochar is a solid, stable, carbon-rich, and highly aromatic material prepared using plant feedstock with a rich pore structure, high specific surface area, and high capacity for holding water and nutrients. This study selected two typical plant resource raw materials, Spartina alterniflora (P. australis) and Spartina alterniflora (S. alterniflora), to prepare biochar at different temperatures, and then investigated the effects of different raw materials and preparation temperatures on the biochar's characteristics. After re-activation treatment, soil improvement experiments were conducted under different carbon application rates. The prepared biochar was alkaline, and contained abundant oxygen-containing functional groups and nutrients (including C, N, Ca, Na, and Mg). Biochar addition had significant effects on the soil microbial community and soil enzyme activity. Finally, by calculating the membership function and factor weights, the various physicochemical and biological properties of the soil were quantified in the form of soil quality indices. The results showed that biochar application had a significant promoting effect on soil quality, mainly through providing rich nutrient sources, enhancing the soil cation exchange capacity and therefore the nutrient effectiveness, and increasing the ability of soil to retain nutrients. The application of biochar (different types) has changed the original nutrient composition, microbial community, and enzyme activity of the soil, and under the combined action of these factors, the soil quality index (SQI) has been improved. This study provides a feasible soil fertility improvement strategy.