Soil bacterial communities are influenced by mulching methods and growth stages in dryland wheat fields

Mulching practices significantly impact nearly all nutrient transformation processes driven by soil microbes. However, the impacts on soil bacterial communities and their correlations with soil nutrient content at maturity remain poorly understood. 

A mulch experiment was conducted to investigate the relationship between soil bacterial communities at major growth stages and the maturity of soil available nutrients in the top 0–20 cm layer of winter wheat in a semi-arid rainfed agricultural area. The experimental treatments included straw strip mulching (42% coverage, SSM), full plastic film mulching (100% coverage, PFM), and conventional flat planting without mulching (control, 0% coverage, CK). Soil bacterial communities were characterized using 16 S high-throughput sequencing.

The results indicate that mulching reduced the α-diversity index of bacterial communities at the grain-filling stage. Furthermore these practices affected the β-diversity at the three growth stages (P<0.001). SSM increased the tightness and complexity at the bacterial genus level compared to CK. It identified four key genera associated with straw decomposition. Conversely, PFM reduced the complexity and increased the tightness at the genus level. SSM increased nitrate nitrogen (NO3−-N) and available potassium (AK) content at maturity compared to CK (P < 0.05). This increase was associated with an increase of Chloroflexi and decrease of Bacteroidota and Verrucomicrobiota in the relative abundance.

SSM enhances the complexity and tightness of soil bacterial communities and increases soil NO3−-N and AK content at maturity. Conversely, PFM has the opposite effect.