保护性耕作对土壤有机碳、氮储量的影响

以辽宁彰武县保护性耕作示范推广基地土壤为研究对象,通过实地调查和取样分析,对比研究了传统犁耕和6年免耕秸秆覆盖条件下的土壤有机碳、氮储量,为广泛评价保护性耕作的土壤碳、氮截获功能和合理选择农业耕作方式提供科学依据。研究结果表明,与犁耕相比,免耕覆盖不同程度地提高了0～5cm和5～15cm土层的有机碳、氮储量,对15cm以下土层没有影响,从而增加了0～100cm土体总的有机碳、氮储量,证明了免耕覆盖的土壤碳、氮截获功能,年均截获率分别为1.37Mg·hm-2和0.84Mg·hm-2。有机碳、氮在犁耕土壤0～30cm剖面的垂直分布较为均匀,免耕覆盖后则发生明显的分层,产生表聚现象。

Soil organic C and N stocks as affected by the conservation tillage

Aimed to comprehensively understand the effects of conservation tillage on interception capacities of soil organic C and N, and to select proper tillage practice for sustainable agriculture, a comparative case study between traditional plow tillage and 6-yr conservation tillage (combination of no-tiUage and straw mulch, CT) in Zhangwu county, Liaoning Province was conducted. The results show that the 6-yr conservation tillage can increase storages of organic C and N in 0～100 cm soil depth, the storages of soil organic C and N in 0～5 cm and 5～15 cm soil depths of the 6-yr conservation tillage are significantly higher than those of the tradition plow tillage soil, while no significant differences are found below 15 cm depth. This indicates that the conservation tillage can inter-cept soil organic C and N, and the interception rates are 1.37 mg C hm~(-2) and 0.84 mg N hm~(-2) per year respectively. The vertical dis-tributions of organic C and N in 0～30 cm soil profile are uniform under the plow tillage, however obvious stratification, i.e. the con-centration near the surface soil under the 6-yr conservation tillage is found.