Combined effects of biochar and silkworm excrement compost applications on soil properties and vegetable growth

Abstract

With the growing global population, the demand for vegetables is increasing rapidly. While the extensive use of chemical fertilizers has been a conventional approach to boost vegetable production, it often degrades soil health and diminishes vegetable quality. This study evaluates the potential of rice husk biochar and silkworm excrement compost as alternative, sustainable biomass fertilizers, examining their impact on yield, quality, soil fertility, and soil microbial communities in Chinese cabbage and lettuce cultivation. Results demonstrated that a combined application of biochar and silkworm excrement compost significantly enhanced the yields of both Chinese cabbage and lettuce. The optimal yield for each crop was achieved at a biochar-to-compost ratio of 2:3, and yields (fresh weight) after this treatment were134 and 103 times higher than the control for Chinese cabbage and lettuce, respectively. In addition, by adjusting the combination ratio of compost and biochar, indicators such as vitamin C, soluble sugar, and soluble protein can be effectively improved, thereby enhancing the quality of vegetables. Compared to control, soil ammonium nitrogen, nitrate nitrogen, available phosphorus, and available potassium showed marked increases in all other treatment soils. In Chinese cabbage soil, compared to other fertility indicators, the highest increase in available phosphorus was observed under biochar-to-compost ratio of 2:3 treatment with an increment of 175.2 % over the control. Furthermore, the biochar-compost combination enhanced soil microbial community structure, raised the Alpha diversity index for soil bacteria, and increased the abundance of key phyla, including Proteobacteria and Actinobacteria. These findings offer new insights and methodological support for advancing sustainable practices within the vegetable industry.