The effects of eight years of conservation tillage on the soil physicochemical properties and bacterial communities in a rain-fed agroecosystem of the loess plateau, China

摘要

Conservation tillage is an alternative to conventional tillage (CT) for addressing the issue of soil degradation, while how it affects soil quality remains unclear. To characterise the temporary and stable effects of 8 years of conservation tillage on soil quality, topsoil (0-20 cm) properties, 16S rDNA-based bacterial community properties and their relationships were analysed. Three tillage practices (CT [as the control], subsoiling tillage [ST] and no tillage [NT]) were compared at the sowing and harvest stages of a continuous winter wheat (Triticum aestivum L.) system. The mean weight diameter of the water-stable aggregate, organic matter, total N/P/K and available K consistently improved with NT at both crop stages, with averages of 26.8, 35.3, 38.5, 29.2, 13.1 and 59.1%, respectively. Similar but lower levels of improvements were observed under ST. Tillage did not significantly affect soil bulk density, penetration resistance and temperature, whereas NT significantly decreased capillary porosity by 7.9% at sowing. At the sowing stage, CT showed higher bacterial alpha/beta-diversity but lower soil water content and abundances of N-cycling bacteria. The physicochemical properties showed significant correlation with the abundances of some genera belonging to Proteobacteria, Nitrospirae and Actinobacteria. After 8 years of experimentation, we found that conservation tillage, especially NT, resulted in stable effects on soil aggregation and nutrient storage. Although soil compaction temporarily decreased after CT, the bacterial community, soil water storage and the aforementioned stable effects were more favourable for soil sustainability under conservation tillage.