Effect of soybean-wheat rotation on soil aggregation, organic nitrogen and net nitrogen mineralization characteristics: a four-year field study

摘要

Long-term, excessive application of synthetic N fertilizers will reduce soil aggregate stability and N supply capacity in corn-wheat (Zea mays L. - Triticum aestivum L.) rotation. This study aimed to determine the effects of soybean (Glycine max L.) on soil aggregation, soil organic N (SON) and net amount of N mineralization (NANM) in wheat season compared with corn. Three rotation systems, corn-wheat (C-W), soybean-wheat (S-W) and soybean inoculated with Rhizobium-wheat (SR-W) were established in 2017. In wet screening, compared with C-W rotation, the mass proportions of large macro-aggregates (LM) + small macro-aggregates (SM) at 0-20 cm was increased by 51.9 and 16.6 under S-W and SR-W rotations, respectively, and was increased by 50.6 and 59.8, respectively, in the 20-40 cm. The proportions of LM + SM-associated N (LMN + SMN), ammonium N (AN) and amino acid N (AAN) were higher under the S-W and SR-W rotations. Furthermore, the NANM of S-W and SR-W rotations increased by 34.1 and 28.6 compared with C-W rotation, respectively, and the non-N benefits of soybean played an important role. In conclusion, the improvement degree of soil aggregation by soybean is an important factor affecting soil N mineralization in wheat season.