Applying deep banding fertilizer is considered an effective strategy to improve grain yield and optimize fertilization management. However, the effect of P fertilizer application depth on P availability in the soil and the key mechanisms enabling the banding of P application to increase yield and efficiency under different soil layers, particularly in the field, remain unclear. We designed a field experiment using winter wheat (Triticum aestivum L.) to explore the effects of different P fertilizer placement depths of 8 cm (DP8), 16 cm (DP16), and 24 cm (DP24) on P availability and root spatial distribution. When compared with No P (no P fertilizer), the available P content of DP8, DP16, and DP24 in the corresponding soil layer increased by 30.0%, 82.4%, and 150.7%, respectively, in the two seasons. This increase in P availability caused a significant increase in the inorganic P (Pi) fractions of dicalcium phosphorus (Ca₂-P), octacalcium phosphorus (Ca₈-P), aluminum phosphorus (Al-P), and iron phosphorus (Fe-P), particularly in the 8–16 cm soil layer. Based on the increase in available P, especially the accumulation of Pi, in different soil layers, the root length density, root surface area density, and root activity were improved. The deeper P application treatments (DP16 and DP24) obtained 9.6–25.2% and 80.1–209.5% higher P uptake and phosphorus-use efficiency, respectively, compared with those of the traditional fertilization depth treatment (DP8). The grain yield increased by 17.0–19.7% and 5.2–8.1% in the DP16 and DP24 treatments, respectively, compared to that in the DP8 treatment. Additionally, the deep banding P application improved the aboveground biomass and harvest index, particularly in DP16, with an increase of 11.8–16.3% and 2.9–4.6% compared with that after DP8 treatment, respectively. Consequently, deep banding P application improved soil P availability and plant growth in the sub-humid area, especially when provided at a depth of 16 cm. Similarly, understanding this mechanism and the interaction between different deep banding P application depths with crops provides a practical reference for optimizing fertilizer management.

施用深条施肥被认为是提高粮食产量和优化施肥管理的有效策略。然而，磷肥施用深度对土壤中磷有效性的影响以及使磷施用条带化以提高不同土壤层特别是田间产量和效率的关键机制仍不清楚。我们设计了一个使用冬小麦 ( Triticum aestivumL.) 探讨不同磷肥施肥深度 8 cm (DP8)、16 cm (DP16) 和 24 cm (DP24) 对 P 有效性和根系空间分布的影响。与无磷（无磷肥）相比，两季相应土层DP8、DP16和DP24的速效磷含量分别增加了30.0%、82.4%和150.7%。磷利用率的增加导致磷二钙 (Ca ₂ -P)、磷八钙 (Ca _{8 -P)、铝磷 (Al-} P ) 和铁磷 (Fe -P)，特别是在 8-16 cm 土层中。基于可用 P 的增加，尤其是 P i的积累，在不同的土层中，根长密度、根表面积密度和根活性都有所提高。与传统施肥深度处理（DP8）相比，深施磷处理（DP16和DP24）分别获得了9.6-25.2％和80.1-209.5％的磷吸收和磷利用效率。与 DP8 处理相比，DP16 和 DP24 处理的粮食产量分别增加了 17.0-19.7% 和 5.2-8.1%。此外，深带磷施用提高了地上生物量和收获指数，特别是在 DP16 中，与 DP8 处理后相比，分别增加了 11.8-16.3% 和 2.9-4.6%。因此，深条施磷提高了半湿润地区土壤磷的有效性和植物生长，尤其是在深度为 16 厘米的情况下。相似地，