间作影响坡耕地红壤团聚体分形特征和抗蚀性的机制

The increasing pollution caused by soil and water erosion from slopping arable land is drawing more and more attention worldwide. Cropping plays a key role in soil and water conservation for arable land. The previous studies mainly focused on evaluation of above ground biomass on reducing surface runoff and scouring by mulching. There are also many reports about effect of land use on soil aggregate and soil anti-erodibility. However, few studies were carried out to investigate different cropping systems on red soil erosion in slopping arable land. From our previous study, we find a significant difference in soil aggregate stability between paddy soil and upland soil. In this study, the main crops of maize, potato and soybean will be selected and their monocropping and intercropping (maize//soybean and maize//potato) in slopping arable land will be studied to investigate 1). Effects of intercropping on fractal characters of red soil aggregate and anti-erodibility in slopping arable land; 2). Mechanism of root characters on formation of red soil aggregate and anti-erodibility; and 3) Mechanism of root exudates on formation of red soil aggregate and anti-erodibility. The results will reveal the effect of intercropping on crop root characteristics and root exudates in sloping arable red soil, and illustrate the responding mechanism for fractal characters of red soil aggregate and anti-erodibility in slopping arable land to root characters and root exudates. The outcomes from this study will provide scientific information for optimization of advantages from both above- and underground parts of cropping systems in order to configure regional soil and water conservation measures and predict soil erosion.

坡耕地红壤水土流失带来的污染日益严峻，农作物是坡耕地水土保持的重要因子。以往对坡耕地红壤农作物保持水土的研究，多集中在地上部分覆盖对坡面径流、冲刷的影响。尽管很多学者研究了不同土地利用方式下团聚体组成及抗蚀性，但却少有人研究不同种植模式对坡耕地红壤侵蚀的影响。项目组前期研究发现，水稻田和玉米地的团聚体稳定性差异显著。本研究拟对云南坡耕地红壤主要农作物玉米、马铃薯和大豆进行单作和间作（玉米//大豆、玉米//马铃薯）种植，深入研究：（1）间作对团聚体分形特征和抗蚀性的影响；（2）根系特征对团聚体形成和抗蚀性的作用机制；（3）根系分泌物对团聚体形成和抗蚀性的作用机制。揭示坡耕地红壤间作对农作物根系特征和根系分泌物的影响，阐明坡耕地红壤团聚体分形特征和抗蚀性对根系特征和根系分泌物的响应机制。通过上述研究可以优化农作物种植模式的地上、地下部分优势，为区域水土流失防治措施配置及土壤侵蚀预报提供理论依据

坡耕地红壤水土流失带来的污染日益严峻，农作物是坡耕地水土保持的重要因子。本研究以云南坡耕地红壤主要农作物玉米、大豆和马铃薯和大豆进行单作和间作（玉米//大豆、玉米//马铃薯）种植，通过3年的实验，主要研究了（1）间作对团聚体分形特征和抗蚀性的影响；（2）根系特征对团聚体形成和抗蚀性的作用机制；（3）根系分泌物对团聚体形成和抗蚀性的作用机制。.结果表明：（1）间作显著改变作物根系特征，不同坡度处理下的间作玉米在0-10cm和20-30cm土层的根长、根表面积和根体积均较单作玉米有增长的趋势，且在0-10cm层的增加尤为显著，而在10-20cm土层则呈下降趋势；间作条件下，玉米大豆有竞争作用，在0-10 cm土层玉米抑制大豆根系的生长，10-20 cm土层时大豆的发达根系会抑制玉米的根系生长。（2）间作显著改善土壤团聚体状况。与单作相比，间作条件下的R0.25、MWD、GMD显著增加，D显著降低。但在不同坡度坡耕地条件下，间作模式下团聚体改善情况较单作模式不明显。（3）间作一定程度上可以通过增加根系促进大团聚体形成，增加固土能力中的弹性形变范围,降低土壤团聚体分形维数，增加固土能力中的塑性形变范围。（4）在10°坡上间作各个粒径的团聚体有机碳含量与玉米单作和大豆单作差异不显著；而在20°和30°坡上间作相比单作提高了不同粒径团聚体有机碳的含量。（5）作物根系特征、根系分泌物分泌量均与土壤团聚体状况呈现相关关系。作物根系特征指标中总根长、总根表面积、总根体积与R0.25、MWD、DMD呈正相关关系，与D呈负相关关系；根系分泌总糖量、总有机酸量与R0.25、MWD、DMD呈正相关关系，与D呈负相关关系。.该研究揭示了不同种植模式下根系特征对团聚体形成和抗蚀性的作用机制。