Abstract：
Future phosphorus (P) shortages could seriously affect terrestrial productivity and food security. We investigated the changes in topsoil available P (AP) and total P (TP) in China\'s forests, grasslands, paddy fields, and upland croplands during the 1980s-2010s based on substantial repeated soil P measurements (63,220 samples in the 1980s, 2000s, and 2010s) and machine learning techniques. Between the 1980s and 2010s, total soil AP stock increased with a small but significant rate of 0.13 kg P ha-1 year-1 , but total soil TP stock declined substantially (4.5 kg P ha-1 year-1 ) in the four ecosystems. We quantified the P budgets of soil-plant systems by harmonizing P fluxes from various sources for this period. Matching trends of soil contents over the decades with P budgets and fluxes, we found that the P-surplus in cultivated soils (especially in upland croplands) might be overestimated due to the great soil TP pool compared to fertilization and the substantial soil P losses through plant uptake and water erosion that offset the P additions. Our findings of P-deficit in China raise the alarm on the sustainability of future biomass production (especially in forests), highlight the urgency of P recycling in croplands, and emphasize the critical role of country-level basic data in guiding sound policies to tackle the global P crises.
摘要：
未来磷（P）短缺可能会严重影响陆地生产力和粮食安全。我们调查了中国森林表层土壤有效磷（AP）和总磷（TP）的变化，草原,稻田,基于大量重复的土壤磷测量（1980年代为63,220个样本，2000年,和2010年代)和机器学习技术。在20世纪80年代和2010年代之间，土壤总AP存量以0.13kgPha-1year-1的小但显著的速率增加，但是在四个生态系统中，土壤总TP储量大幅下降（4.5kgPha-1year-1）。我们通过协调这一时期来自各种来源的P通量来量化土壤-植物系统的P预算。将几十年来土壤含量的趋势与磷预算和通量相匹配，我们发现，与施肥相比，由于巨大的土壤TP池以及通过植物吸收和水蚀而导致的大量土壤P流失，抵消了P的增加，因此耕地（尤其是高地农田）中的P过剩可能被高估。我们对中国磷赤字的发现对未来生物质生产的可持续性(尤其是森林)提出了警告。强调农田磷回收的紧迫性，并强调国家一级基础数据在指导应对全球P危机的健全政策方面的关键作用。
