Background and aims

Litter input plays an important role in maintaining soil phosphorus (P) availability in terrestrial ecosystems. Moreover, nitrogen (N) deposition can alter litter accumulation and decomposition and, consequently, soil P availability. However, the combined effects of N and litter addition on soil P availability remain unclear.

Methods

We examined how N addition (0 and 10 g N m⁻² yr⁻¹) and litter manipulation (initial litter, litter removal and litter addition) affected the seasonal dynamics of soil P availability in an 11-year grassland experiment.

Results

During the mid-growing season, N addition significantly increased soil available P but decreased soil total P, while litter addition increased soil total P. At the end of the growing season, litter addition increased soil available P, while N addition increased soil total P. Structural equation modelling (SEM) revealed that N addition increased soil available P by increasing aboveground biomass and decreasing soil pH during the mid-growing season. At the end of the growing season, litter addition increased soil available P by enhancing microbial biomass P.

Conclusion

Our findings suggested that N and litter addition increased soil P availability from the middle to the end of the growing season. Moreover, the positive effects of litter on soil available and total P under N addition at the end of the growing season indicated that grassland management that reduce litter accumulation, such as grazing and mowing, may decrease the soil P supply under increased N deposition.

中文翻译：

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在生长季节添加氮和凋落物可以提高土壤磷的利用率

背景和目标

凋落物输入在维持陆地生态系统土壤磷 (P) 可用性方面发挥着重要作用。此外，氮（N）沉降可以改变凋落物的积累和分解，从而改变土壤磷的有效性。然而，氮和凋落物添加对土壤磷有效性的综合影响仍不清楚。

方法

我们在为期 11 年的草原实验中研究了氮添加（0 和 10 g N m ^-2  yr ^{-1 ）和凋落物处理（初始凋落物、凋落物去除和凋落物添加）如何影响土壤磷有效性的季节性动态。}

结果

在生长季中期，施氮显着增加了土壤速效磷，但降低了土壤全磷，而添加凋落物则增加了土壤全磷。在生长季末，添加凋落物增加了土壤速效磷，而施氮则增加了土壤全磷。结构方程模型 (SEM) 表明，在生长中期，添加氮可通过增加地上生物量和降低土壤 pH 值来增加土壤有效磷。在生长季节结束时，添加凋落物通过增加微生物生物量 P 来增加土壤有效磷。

结论

我们的研究结果表明，氮和凋落物的添加增加了生长季节中期到末期土壤磷的有效性。此外，在生长季结束时添加氮的情况下，凋落物对土壤有效磷和总磷的积极影响表明，减少凋落物积累的草地管理，如放牧和割草，可能会在氮沉降增加的情况下减少土壤磷的供应。