Straw retention has the potential to improve soil phosphorus (P) availability, but the question on how straw retention under different P level influences the activity of soil P-related enzymes and thus the transformfiation of soil organic P (Po) remains poorly understood. A four-year field experiment (2016–2019) was established to investigate the impacts of straw retention under different P fertilizer levels (0, 44, 88 kg P ha^–1) on soil P fractions, the activity of P-related enzymes, and the abundance of phoC and phoD genes. Results demonstrated that P application alone significantly increased all soil inorganic P (Pi) fractions, but had no significant impact on soil Po fractions. Straw retention combined with P fertilizer mainly improved the proportion of NaHCO₃-Po (labile P) and NaOH-Pi (moderately labile P), while decreased the proportion of dilute HCl-P and residual-P (non-labile P). The application of straw plus P fertilizer of 44 kg P ha⁻¹ increased the contents of resin-Pi and NaHCO₃-Pi more than straw plus 88 kg P ha⁻¹. Also, the former had higher activity of alkaline (ALP) and acid phosphatase (ACP) and abundance of phoD gene than the latter. The structural equation model indicated that soil ALP and phytase (PHY) had a significant and positive effects in P cycling. Soil organic carbon (C), C:P ratio, and water-organic C were positively correlated with the activity of ALP and PHY, and the abundance of phoD gene. These findings together demonstrate that crop straw combined with a moderate amount of P fertilizer (44 kg P ha⁻¹) is more beneficial for soil P availability through enhancing the activity of PHY and ALP and the abundance of phoD and phoC genes.

秸秆保留有可能提高土壤磷 (P) 的有效性，但关于不同 P 水平下秸秆保留如何影响土壤 P 相关酶的活性以及土壤有机磷 (Po) 转化的问题仍然知之甚少。建立了一项为期四年的田间试验（2016-2019 年），研究不同磷肥水平（0、44、88 kg P ha ^–1）下秸秆保留对土壤 P 组分、P 相关酶活性、以及丰富的phoC和phoD基因。结果表明，单独施磷显着增加了所有土壤无机磷（Pi）分数，但对土壤磷分数没有显着影响。秸秆保留与磷肥配合主要提高了NaHCO ₃ -Po（不稳定P）和NaOH-Pi（中度不稳定P）的比例，同时降低了稀HCl-P和残留-P（不稳定P）的比例。秸秆加磷肥44 kg P ha ^-1比秸秆加88 kg P ha ^-1的树脂-Pi和NaHCO ₃ -Pi含量增加更多。此外，前者具有较高的碱性（ALP）和酸性磷酸酶（ACP）活性和丰富的phoD基因高于后者。结构方程模型表明，土壤碱性磷酸酶和植酸酶（PHY）对磷循环具有显着的积极影响。土壤有机碳(C)、C:P比和水-有机C与ALP和PHY的活性以及phoD基因的丰度呈正相关。这些发现共同表明，农作物秸秆与适量的磷肥（44 kg P ha ^{-1 ）相结合，通过增强 PHY 和 ALP 的活性以及}phoD和phoC基因的丰度，更有利于土壤磷的有效性。