Promotive effect of mechanochemically crushed straw on rice growth by improving soil properties and modulating bacterial communities

The traditional approaches for utilizing straw as a growth support for plants in their initial growth phases may not be optimal owing to its protracted decomposition rate. We aim to address this problem by improving the degradation rate of straw through mechanochemical crushing, which can significantly expedite the process. Moreover, there remains a lack of clarity regarding the mechanisms responsible for the positive impact of mechanochemically crushed straw on rice growth. To gain a better understanding of the differences between using whole straw and mechanically crushed straw, this study investigates how mechanical crushing affects the structure of straw. Additionally, this study has examined the effects of incorporating mechanochemically crushed straw into paddy soil on bacterial communities, soil properties, and the growth of rice plants. In this investigation, whole straw was employed and two distinct methodologies for straw crushing were implemented, involving one instance of straw subjected to a 10 min crushing duration and another subjected to a 20 min crushing duration (SC20), while a control group was maintained devoid of any treatment. Our results demonstrated that the SC20 treatment significantly improved plant height (25.1%) and fresh (74.6%) and dry weight (76.3%) and increased soil nutrients, such as soil organic carbon (31.6%), total nitrogen (20.0%), available potassium (53.5%), available phosphorus (50.8%), microbial biomass carbon (48.4%) and microbial biomass nitrogen (52.2%), but significantly decreased soil pH (from 7.22 to 7.07) compared to the control group. The relative distribution of several specific bacteria, including WCHBI-32, Anaeromyxobacter and Anaerolinea, was significantly increased in both treatments, but the structure of the soil bacterial community was modulated by mechanochemically crushed straw, which were found to enhance carbon-related functional groups, but simultaneously reduce nitrogen-related functional groups in the soil. Overall, these findings suggest that incorporating crushed straw in paddy soil can alter soil properties, influence the microbial community and promote the growth of rice crop.