免耕覆盖措施下蚯蚓活动对土壤团聚体及有机碳的影响

Effects of earthworm activity on soil aggregates and organic carbon under no-till mulching measures

目的探究免耕覆盖措施下,蚯蚓种群数量对秋玉米农田土壤团聚体组成及土壤有机碳含量的影响。方法采用大田试验的方法,设置4个蚯蚓接种处理,分别为NTSE_(0)(对照组,0条/m^(2))、NTSE_(20)(2条/m^(2))、NTSE_(50)(5条/m^(2))、NTSE_(100)(11条/m^(2))。结果(1)与对照组相比,蚯蚓活动主要提高了0.25~0.5 mm(6.28%~50.62%)、0.5~1 mm(0.51%~41.24%)和1~2 mm(4.18%~25.68%)的团聚体含量。足够数量的蚯蚓活动可提高土壤团聚体的稳定性,与对照组相比,蚯蚓活动可提高0.88%~14.67%的平均重量直径(MWD)和1.41%~8.20%的几何平均直径(GMD)。(2)蚯蚓活动改变了土壤有机碳含量。与对照组相比,在0-100 cm土层(除0-20 cm),NTSE_(20)提高了土壤有机碳含量(0.23~1.54 g/kg),而在0-100 cm土层,NTSE_(50)和NTSE_(100)均降低了土壤有机碳含量(分别为0.32~2.66 g/kg和0.06~0.94 g/kg),说明适量的蚯蚓接种可以提高土壤有机碳;蚯蚓活动引起的团聚体稳定性与土壤总有机碳之间在0-60 cm土层呈负相关关系,在61-100 cm土层呈正相关关系。结论蚯蚓活动提高了土壤中的较大团聚体的数量及团聚体稳定性,改变了土壤有机碳含量。对关中平原秸秆还田实践中引入蚯蚓接种手段及蚯蚓活动对于改良土壤结构及提高土壤肥力提供数据支持,具有现实指导意义。

Purposes—To investigate the effects of earthworm population size on soil aggregate composition and soil organic carbon in autumn maize farmland under no-till mulching measures.Methods—Four earthworm inoculation treatments were set up through field experiment,NTSE_(0)(control group,0 earthworms/m^(2)),NTSE_(20)(2 earthworms/m^(2)),NTSE_(50)(5 earthworms/m^(2)),and NTSE_(100)(11 earthworms/m^(2)),respectively.Results—(1)Compared with the control group,earthworm activity mainly increased the agglomerate content of 0.25~0.5 mm(6.28%~50.62%),0.5~1 mm(0.51%~41.24%)and 1~2 mm(4.18%~25.68%).Compared with the control group,sufficient amount of earthworm activity improved the stability of soil aggregates,with earthworm activity increasing the mean weight diameter(MWD)by 0.88%to 14.67%and the geometric mean diameter(GMD)by 1.41%to 8.20%.(2)Earthworm activity altered soil organic carbon.Compared with the control group,NTSE_(20)increased soil organic carbon(0.23~1.54 g/kg)in the 0-100 cm soil layer(except 0-20 cm),while NTSE_(50)and NTSE_(100)decreased soil organic carbon(0.32~2.66 g/kg and 0.06~0.94 g/kg respectively)in the 0-100 cm soil layer.This indicates that earthworm inoculation at appropriate levels can increase soil organic carbon,and there is a negative correlation between cluster stability caused by earthworm activity and total soil organic carbon in the 0-60 cm soil layer but a positive correlation in the 61-100 cm soil layer.Conclusions—The results of this study showed that earthworm activity increased the number and stability of larger aggregates in the soil and changed the soil organic carbon content,and it is of data support and practical significance not only to guide the introduction of earthworm inoculation methods and earthworm activities in the practice of straw returning to the field in Guanzhong area but also to improve soil structure and soil fertility.