蚯蚓生物耕作对油-稻免耕系统耕层结构的改善机制

It was easy to cause soil compaction and poor soil structure of ploughed layer with mechanical harvesting under no-tillage systems, which threatened the sustainable use of no-tillage paddy fields. Earthworm bio-tillage is one of the effective ways to improve the soil structure of ploughed layer in upland, but its role in the paddy field system is still unclear. Therefore, this project is planned to study on the mechanism of earthworm bio-tillage improve ploughed layer structure in the rotation system of oilseed rape and rice with no-tillage systematically, by combining field test with mechanical harvesting compaction and indoor culture experiments, which are based on the paddy-upland rotation system of rape and rice for 10 years with no-tillage. Field trial will be conducted to study the temporal and spatial distribution law of earthworm populations, and then the distribution characteristics of earthworm populations after mechanical harvesting compaction will be determined; by using CT scanning technology and microelectrode measurement systems and other technical means, the changes of ploughed layer structure in the rape and following rice seasons will be studied before and after earthworm inoculation, thus, the effects of earthworm bio-tillage on ploughed layer structure will be elucidated; moreover, the intrinsic relationship between the growth of rape and following rice and the ploughed layer structure will be researched, to reveal the effect of earthworm bio-tillage improve ploughed layer structure and its effect on the growth of rape and rice. The results of this project will provide scientific basis for promoting the soil structure recovery of mechanical harvesting compaction in a no-tillage paddy system.

免耕系统下的机械收获易造成耕层土壤压实，导致耕层结构变差，进而威胁免耕稻田的可持续利用。蚯蚓生物耕作是改善旱地土壤耕层结构的有效途径之一，但其在稻田系统中的作用机制尚不清楚。本项目拟以连续免耕10年的油-稻水旱轮作系统为依托，通过田间机械收获压实试验与室内培养实验相结合，系统研究蚯蚓生物耕作对油-稻免耕系统耕层结构的改善机制。通过田间试验，研究蚯蚓种群的时空分布规律，明确机械收获压实后蚯蚓种群分布特征；通过CT扫描技术与微电极测量系统等技术手段，研究蚯蚓接种前后油菜季及后茬水稻季的耕层结构变化，阐明蚯蚓生物耕作对耕层结构的影响；并开展油菜及后茬水稻生长与耕层结构之间内在联系研究，揭示蚯蚓生物耕作对耕层结构的改善作用及其对油菜、水稻生长的作用机制。其研究成果可为促进免耕稻田系统机械收获压实的土壤结构恢复提供科学依据。

免耕系统下的机械收获易造成耕层土壤压实，导致耕层结构变差，进而威胁免耕稻田的可持续利用，而蚯蚓生物耕作是改善耕层结构的重要手段。本项目通过CT扫描技术与微电极测量系统等技术手段，研究了油-稻免耕系统蚯蚓接种后油菜季及后茬水稻季田间压实区与非压实区的耕层结构变化，发现蚯蚓生物耕作可显著降低表土容重及紧实度，增加土壤的大团聚体含量。通过冬种油菜及蚯蚓生物耕作可显著增加免耕压实下的土壤总孔隙度，大幅增加免耕压实下2000um以上的土壤大孔隙度，降低压实区与非压实区的孔隙差，并显著增加了土壤氧浓度，改善了耕层结构。机械压实会显著降低油菜的单位面积苗数、株高、干物质积累量、净光合速率，通过蚯蚓生物耕作可使上述生物学指标得到显著增加，从而显著提高油菜及水稻产量，降低压实区与非压实区之间油菜及水稻的产量差，从而有效缓解油-稻免耕系统机械压实对作物产量的不利影响。项目研究期间发表研究论文3篇，授权国家发明专利1件，培养硕士研究生1名，全面完成了项目的研究目标。通过本项目的实施，揭示了蚯蚓生物耕作对油-稻免耕系统耕层结构的改善机制，研究结果对于指导油-稻免耕系统的高效可持续利用具有重要的应用价值。