不同耕作方式下蚯蚓和秸秆还田对土壤氮素的影响

摘要

免耕能够减少土壤扰动和增加有机物质还田,进而增加蚯蚓数量;蚯蚓又可以显著影响土壤结构和土壤有机质变化.然而免耕下蚯蚓和秸秆互作如何影响黑土中氮的分布和周转,尚需要深入的探讨.本研究通过室内对原状土壤进行蚯蚓和秸秆添加培养实验,分析传统性耕作和免耕下蚯蚓和秸秆还田对土壤总氮及其活性组分的影响.结果表明,免耕下所有处理土壤总氮和活性氮含量都分别高于或者等于传统耕作土壤;秸秆和蚯蚓添加在不同耕作方式下对土壤总氮和活性氮的作用不同;传统耕作下新添加秸秆会降低土壤活性氮含量,免耕下新添加秸秆则会降低土壤总氮和活性氮含量;蚯蚓在传统耕作土壤中能够降低活性氮含量,免耕土壤中蚯蚓则增加总氮和活性氮的含量.蚯蚓和秸秆在传统性耕作中表现出的综合作用会小于其单一影响,但仍然起着降低氮含量的作用;免耕下蚯蚓和秸秆共同存在的综合作用也会抵消一部分作用,使得土壤氮素含量介于蚯蚓和秸秆单一添加处理土壤.本研究结果有助于我们在实际生产中选择合理的耕作措施和秸秆还田量,培肥土壤,减少化肥施用量.%No tillage greatly increases earthworm abundance due to low disturbance and residue returning , while earthworms strongly influence soil structure and soil organic matter dynamics as well .How will earthworms combined with residue returning affect distribu-tion and decomposition of soil N? Aiming at understanding the effects of earthworms and straw adding on total N and active nitrogen fractions , by using undisturbed soils , we conducted a 30-day incubation experiment with earthworms and maize residue additions un-der no tillage ( NT) and conventional tillage ( CT) systems.The results showed that the contents of soil total nitrogen and soil active nitrogen in NT were higher than those in CT or equal to CT .The effects of earthworm and straw on soil nitrogen dynamics were different under CT and NT.The addition of straw decreased soil active nitrogen content in CT and the total nitrogen and active nitrogen contents in NT, respectively.In contrast, the earthworm decreased soil active nitrogen content in CT , while increased the total nitrogen and ac-tive nitrogen content in NT.The effect of earthworm and straw coexisting in conventional tillage would be less than the effect of a single role but still played a role in reducing nitrogen content;parts of the effect from earthworm and straw coexisting in NT was offset com-pared with the influence of single factor ( earthworm or residue returning ) , which resulted in the N content ranging between the values under single earthworm and single straw treatments .This result would help us to select the appropriate farming measures and find out the optimal amount of straws returned to the field for maintaining soil fertility and reducing soil fertilizer .