Effects of Different Crop Rotation Patterns on the Growth of Guizhou Sorghum and the Quality of Its Rhizosphere Soil

As a crop with prominent continuous cropping obstacles, sorghum was studied to explore the effects of different planting patterns on its growth and soil microenvironment in Guizhou. Three treatments were set up: sorghum-sorghum-sorghum continuous cropping(SSS), sorghum-rapeseed-sorghum rotation(SRS), and sorghum-stem mustard-sorghum rotation(SMS). The differential impacts of these patterns on the growth of subsequent sorghum, rhizosphere soil quality, and soil microbial structure were compared. The results showed that: In terms of crop growth, compared with the SSS treatment, the SRS and SMS patterns enhanced sorghum root activity, improved aboveground growth, and increased yield. For soil physical and chemical properties, soil organic matter, total nitrogen, total phosphorus, total potassium, and alkali-hydrolyzable nitrogen under SRS and SMS were higher than those under SSS, and soil pH was increased. The activities of urease and invertase in the SRS treatment were the highest, increasing by 39% and 56% respectively compared with SSS. Analysis of sorghum rhizosphere soil microorganisms showed that compared with SSS, the SRS and SMS patterns altered the composition of the rhizosphere microbial community. The SRS pattern had the lowest ratio of bacterial to fungal OUTs, while there was no significant difference between SMS and SSS. alpha-diversity indicated differences in microbial community abundance and diversity among planting patterns, and beta-diversity showed obvious differences in microbial communities, with more significant differences in bacterial communities. At the fungal phylum level, SRS rotation increased the relative abundances of Basidiomycota and Mortierellomycota and decreased that of Ascomycota. Correlation analysis revealed that soil organic matter(SOM), total potassium(TK), available potassium(AK), available phosphorus(AP), and invertase(INV) were key environmental factors influencing soil microbial community structure. In conclusion, sorghum rotation can improve the soil microenvironment, regulate the soil microbial community structure, alleviate continuous cropping obstacles, and enhance sorghum quality and yield.