Influence of Green Manure Rapes Returning and Biochar Application on Soil Carbon and Nitrogen Statuts of Newly Built Green Houses
摘要
In order to reasonably and efficiently improve the soil fertility of newly built greenhouses, the effects of rapeseed returning to the field and applying biochar on soil carbon and nitrogen and subsequent crops were studied, and the optimal combination of green manure rapeseed and biochar was sought. The study designed four rape returning levels (fresh weight 7500, 15000, 22500, 45000 kg·hm−2) and two biochar application levels (0%, 1%), and no returning and no biochar application as controls, a total of nine treatments. The maximum increase in total carbon, light fraction organic carbon, dissolved organic carbon (DOC), microbial biomass carbon nitrogen, total nitrogen, heavy fraction organic nitrogen, and urease activity was observed in the F6 treatment, which significantly increased by 85.60%, 86.98%, 65.09%, 170.73%, 266.99%, 24.59%, 19.81%, and 26.16% compared to the basic soil, respectively. The maximum increase in soil heavy organic carbon was observed in F4 treatment. The maximum increase in soil light fraction organic nitrogen was observed in F5 treatment. In the correlation analysis between crop yield, total dry matter quality, nutrient absorption and soil C and N indicators, the correlation with soil urease activity, DOC, total carbon, and light fraction organic carbon is the highest. The treatment of 1% biochar and returning quantity 2.25 × 104 kg·hm−2 (F6) had the best effect on soil carbon and nitrogen, the most significant effect on dry matter quality, nutrient absorption and yield of subsequent crops, and the combination of 1% biochar and returning quantity 1.50 × 104 kg·hm−2 (F4) had the second effect. This study clarified the optimal amount of biochar and green manure combined in the process of soil fertility improvement in newly constructed greenhouses through the changes in soil carbon and nitrogen indicators, providing a reference for subsequent experiments and soil fertility improvement.