秸秆覆盖条件下紫云英间作油菜的土壤团聚体及有机碳特征

我国西南旱地紫色土区水土流失严重、土层浅薄、土壤有机质下降、保水保土能力差,已成为农业可持续发展的主要限制因素.通过引入冬季绿肥紫云英,研究秸秆覆盖条件下紫云英间作油菜的土壤团聚体及有机碳特征,为该地区改善农田土壤团聚体结构和提高有机碳含量提供可借鉴的途径.结果表明: 间作紫云英增加了油菜根际土壤微团聚体含量,促使其团聚体平均质量直径降低.油菜根际土壤大团聚体含量的变化主要是由10～5 mm和5～2 mm团聚体含量的变化引起,而微团聚体含量的变化主要是由0.25～0.053 mm团聚体含量的变化引起.间作紫云英和秸秆覆盖显著提高了后茬作物玉米季土壤有机碳含量,主要是因为影响了10～20 cm和20～30 cm土层总有机碳的含量.间作紫云英和秸秆覆盖虽然对油菜季总有机碳含量的增加不明显,但对0～10 cm、10～20 cm和20～30 cm土层总有机碳含量的影响却随着油菜生育期的进行逐渐增加,在蕾薹期、开花期和收获期表现出较大差异.可见,间作紫云英改变了油菜根际土壤团聚体特征,秸秆覆盖条件下紫云英间作油菜可提高农田土壤有机碳含量.

Effects of Chinese milk vetch intercropped with rape under straw mulching on soil aggregate and organic carbon character

There are severe soil erosion, shallow soil, reduction of soil organic matter, and poor soil and water conservation in purple soil areas in Southwest China, which become the main limiting factors for the sustainable development of agriculture. A series of buckets and field experiments in the field were employed to explore the soil aggregate and soil organic carbon in response to Chinese milk vetch intercropped with rape under straw mulching, aiming to improve soil aggregate structure and increase organic carbon content. Results showed that intercropped Chinese milk vetch increased soil micro-aggregate content in rape rhizosphere, and reduced soil aggregate mean mass diameter. The change of soil macro-aggregate in rape rhizosphere was mainly caused by the change of content of soil aggregate on 10-5 mm and 5-2 mm, while the soil micro-aggregate was mainly caused by soil aggregate on 0.25-0.053 mm. Intercropped Chinese milk vetch and straw mulching significantly increased soil organic carbon content after corn growing season, with increasing the content of soil organic carbon on 10-20 cm and 20-30 cm. Though intercropped Chinese milk vetch and straw mulching had less effect on soil total organic carbon in rape season, more and more significant effect on 0-10 cm, 10-20 cm, and 20-30 cm with rape growing, especially in stem elongation stage, flowering stage, and harvest stage. Our results showed that the characteristic of soil aggregate in rape rhizosphere could be changed by intercropped Chinese milk vetch, and that the content of soil organic carbon could be increased by Chinese milk vetch intercropped with rape under straw mul-ching.