Plow tillage with buried straw increases maize yield by regulating soil properties, root growth, photosynthetic capacity, and bacterial community assembly in semi-arid black soil farmlands

Abstract

Combined plow tillage and buried straw sustainably increases maize yields. However, how it regulates the temporal and spatial-temporal dynamics of soil properties, maize growth, and bacterial community assembly in semi-arid black soil agricultural fields remains unclear. Therefore, we aimed to evaluate the changes in soil properties, root growth, photosynthetic capacity, and bacterial assembly and their contributions to maize yield after 7 years of different straw-returning treatments. The experiment comprised no-tillage straw-mulching (NTSM), plow tillage with buried straw (PTBS), and rotary-tillage straw removal (RTS-). We used high-throughput sequencing to investigate the bacterial community structures and assembly in different seasons and soil depths and assessed soil properties, root growth, and photosynthetic capacity. Compared with the effects observed under NTSM, PTBS improved average 0–40 cm soil layer nutrient content, promoted root growth, and improved photosynthetic rate, increasing yield. NTSM and PTBS treatments significantly changed the soil bacterial community structure and increased the relative abundance of beneficial bacteria. PTBS treatment significantly enhanced carbon-nitrogen-related functional groups. PTBS microbial community showed high microbial diversity and highly deterministic bacterial assembly processes. The dominant genera and biomarkers enriched in the different treatments had similar correlated environmental factors but opposite correlation trends. Soil nutrients, root growth, and photosynthetic rate explained most of the variations in annual maize yield, while bacteria indirectly affected annual yield through nutrient and root characteristics. Our results indicate that soil nutrients, root growth, photosynthetic rate, and bacteria contribute to maize yield increase in plow tillage with buried straw treatment. NTSM only benefits the soil nutrients in the topsoil.