Abstract. Soil extracellular enzymes are central in terrestrial ecosystem responses to climate change, and their research can be crucial for assessing microbial nutrient demand. However, the effects of climate-induced precipitation patterns on soil microbial nutrient demand in different soil profiles of agroecosystems are rarely studied. Here, we present how the precipitation gradient affects soil enzymes related to carbon (C), nitrogen (N) and phosphorus (P) cycling and identified microbial nutrient limitation determinants at five depth intervals (0–10, 10–20, 20–30, 30–40 and 40–50 cm) in seven agroecosystems. We found that N- and P- acquiring enzymes have a tendency to increase or decrease, but C- acquiring enzymes did not change along the precipitation gradient throughout soil profiles. Soil pH and moisture were the most important factors affecting the enzyme activity in 0–50 cm. Our results also revealed a crucial soil boundary (at 20 cm) that differentiated responses of microbial nutrient limitation to precipitation changes. In the topsoil (0–20 cm), the stoichiometry of soil nutrients did not vary with precipitation. Microbial P limitation was exacerbated with increased precipitation, which was controlled by soil pH and moisture in the topsoil. In contrast, in the subsoil (20–50 cm), soil nutrient stoichiometry decreased with increasing precipitation, and microbial C and P limitation displayed a positive correlation with precipitation. Furthermore, microbial P limitation tended to be stronger in the subsoil than in the topsoil along the precipitation gradient. Microbial C and P limitation was regulated by the soil nutrients and their stoichiometry in the subsoil. Our study is an essential step in soil enzyme activity and stoichiometry response to precipitation in agroecosystems and provides novel insights into understanding microbial nutrient limitation mechanisms in soil profiles along the precipitation gradient.

中文翻译：

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农业生态系统降水梯度下土壤中更强的微生物养分限制：来自土壤酶活性和化学计量的见解

摘要。土壤细胞外酶是陆地生态系统对气候变化的反应的核心，它们的研究对于评估微生物营养需求至关重要。然而，很少研究气候诱导的降水模式对农业生态系统不同土壤剖面中土壤微生物养分需求的影响。在这里，我们介绍了降水梯度如何影响与碳 (C)、氮 (N) 和磷 (P) 循环相关的土壤酶，并在五个深度间隔 (0-10、10-20、20-30) 确定了微生物养分限制决定因素。 , 30-40 和 40-50 cm) 在七个农业生态系统中。我们发现N-和P-获取酶有增加或减少的趋势，但C-获取酶没有沿着整个土壤剖面的降水梯度发生变化。土壤 pH 值和水分是影响 0-50 cm 酶活性的最重要因素。我们的研究结果还揭示了一个关键的土壤边界（20 cm），它区分了微生物养分限制对降水变化的反应。在表土（0-20 cm）中，土壤养分的化学计量不随降水变化。微生物磷的限制随着降水的增加而加剧，这是由土壤 pH 值和表土中的水分控制的。相比之下，在底土（20-50 cm）中，土壤养分化学计量随着降水量的增加而降低，微生物C和P限制与降水量呈正相关。此外，沿降水梯度，下层土壤中的微生物磷限制往往强于表层土壤。微生物 C 和 P 限制受土壤养分及其在底土中的化学计量的调节。我们的研究是农业生态系统中土壤酶活性和对降水的化学计量响应的重要步骤，并为了解沿降水梯度的土壤剖面中的微生物养分限制机制提供了新的见解。