文献类型： 外文期刊

作者： Liu Xiu;Dong Wenyi;Jia Shaohui;Liu Qian;Li Yuzhong;Hossain Md Elias;Liu Enke;Kuzyakov Yakov

作者机构：

关键词： 15N-labelled wheat straw; Conventional tillage; Labile N fractions; Long-term no-tillage; Microbial nitrogen immobilization; Nitrogen mineralization

期刊名称： Science of the Total Environment

ISSN： 0048-9697

年卷期： 2021 年 786 卷

页码：

收录情况： JCR（2021版） ; EI（2021版）

摘要： Understanding wheat straw nitrogen (N) transformations in soil depending on tillage practices is necessary to increase the efficient N use and to protect dryland farming environments. Labile organic N pools are crucial for N mineralization but are less investigated because of their fast dynamics. The objectives of this study were to determine the effects of winter wheat straw N (15N-labelled) on soil labile organic N transformations under long-term (27 years) no-tillage and conventional tillage. Four treatments were established under controlled conditions: no-tillage without straw (NoTill); no-tillage with 15N-labelled wheat straw (NoTill+Straw); conventional tillage without straw (ConvTill); and conventional tillage with 15N-labelled straw (ConvTill+Straw). Straw application increased the particulate organic matter N (POMN) and microbial biomass N (MBN) contents, especially in NoTill+Straw, but decreased the dissolved organic N (DON) content. This reflects intensive microbial DON immobilization at the background of plant residues with a high C/N ratio. The 40% to 80% increase in the NH4+ content after straw addition reflects fast straw and soil organic matter (SOM) mineralization, while NO3− declined by 60% to 93% over 56 days, especially in ConvTill soil. 15N recovered in POMN after 14 d was greatest in NoTill+Straw and ConvTill+Straw, reaching 20 and 18 mg 15N kg−1, respectively. Overall, the straw N recovered as NO3− was 72% and 48% greater than that in NH4+ in ConvTill+Straw and NoTill+Straw, respectively, reflecting accelerated SOM mineralization and N mining in the presence of straw. The straw N recovered as POMN was greater through the incubation period (56 days) than that in DON and MBN, especially in NoTill+Straw, indicating that the no-tillage practice reduced straw mineralization. 15N in DON and 15N in NO3− were higher in NoTill+Straw than in ConvTill+Straw, implying that N limitation was alleviated to a certain extent under no-tillage conditions. In conclusion, wheat straw N remained mainly in POMN after 56 days, especially under no-till conditions, and only a minor part was incorporated into DON and microbial biomass. This provides a theoretical basis for straw N use efficiency in agroecosystems. © 2021 Elsevier B.V.

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