Decreased inorganic N supply capacity and turnover in calcareous soil under degraded rubber plantation in the tropical karst region

文献类型： 外文期刊

第一作者： Garousi, Farzaneh

作者： Garousi, Farzaneh;Yang, Hui;Cao, Jianhua;Jiang, Zhongcheng;Zhu, Tongbin;Shan, Zhijie;Ni, Kang;Yang, Hui;Cao, Jianhua;Zhu, Tongbin;Shan, Jun;Yang, Jinling;Mueller, Christoph;Mueller, Christoph

作者机构：

关键词： Degraded rubber plantation; N-15 tracing; Gross N transformation; Autotrophic nitrification; Inorganic N supply capacity

期刊名称：GEODERMA （ 影响因子：6.114； 五年影响因子：6.183 ）

ISSN： 0016-7061

年卷期： 2021 年 381 卷

页码：

收录情况： SCI

摘要： Investigating soil inorganic nitrogen (N) supply and availability can guide soil improvement of rubber (Hevea brasiliensis) plantations in tropical regions, but the mechanisms controlling the inorganic N supply remain unknown. In this study, three natural forests and three degraded rubber plantations located in a tropical karst region of southwestern China were sampled to determine the gross N transformation rates using a N-15 tracing method. The soils of the natural forests were characterized by a high inorganic N supply capacity and a high-level nitrate (NO3-) production potential, due to the high rates of organic N mineralization to ammonium (NH4-) (M-Norg) and NH4+ oxidation to NO3- (O-NH4) but relatively low rates of immobilization of NH4+ (I-NH4) and NO3- (I-NO3) to organic N and dissimilatory NO3- reduction to NH4+ (DNRA). In the soils of the degraded rubber plantations, the rates of M-Norg, O-NH4, I-NO3, and DNRA were lower but the rates of NH4+ adsorption on cation-exchange sites (A(NH4)) increased, resulting in reductions in the inorganic N supply capacity and N availability. In addition, NO3 turnover in the soils of the degraded rubber plantations decreased, accompanied by a high mean residence time of NO3- and low delta N-15 values. Soil total N, organic C, phosphorus, and potassium concentrations, waterholding capacity, cation-exchange capacity, and sand content were significantly lower in the soils of the degraded rubber plantations than in those of the natural forests, indicating a decline in soil quality in the former. The significant, positive relationships between these soil properties and the rates of M-Norg, O-NH4, I-N(O3), and DNRA highlight the importance of the appropriate application of organic N fertilizers as well as phosphorus and potassium fertilizers to stimulate soil N cycling and thereby increase the inorganic N supply. A reduction of the N deficiency in soils used for rubber tree cultivation would alleviate the soil degradation that characterizes many rubber plantations in tropical karst regions.

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