Abstract: In order to provide a theoretical basis for the efficient utilization of phosphate fertilizer in foxtail millet production，a field experiment was conducted with four phosphate fertilizer application depths of 5 cm（P5），10 cm（P10），15 cm（P15）and 20 cm（P20）with no phosphate fertilizer application as control（CK），and the effects of phosphorus fertilizer application depth on root distribution，dry matter accumulation and transportation，nitrogen uptake and utilization，and yield of foxtail millet were studied.The results showed that suitable application depth of phosphate fertilizer promoted the growth of foxtail millet roots，and increased root length，root surface area and dry weight of root，showing a trend of P15>P10>P5>P20>CK. With the increase of phosphate fertilizer application depth，the root length，root surface area and dry weight of root of foxtail millet in deep soil increased，and the values showed P20>P15>P10>P5>CK in 20—40 cm soil layer. Suitable application depth of phosphate fertilizer could promote dry matter accumulation and transportation of foxtail millet. Compared with P5 treatment，the dry matter accumulations at maturity of P10，P15 and P20 treatments increased by 4.60%，10.29% and 0.92%，respectively，and the dry matter transfer rates increased by 6.49%，10.06% and -20.13%，respectively.Deep application of phosphate fertilizer increased the uptake and utilization of nitrogen by roots in deep soil.The available nitrogen content in deep soil，especially in the 20—40 cm soil layer，significantly decreased compared with P5 treatment. Compared with P5 treatment，the total nitrogen accumulations of P10，P15 and P20 treatments increased by 3.91%，17.85% and 5.31% at maturity，respectively；nitrogen absorption efficiencies increased by 5.88%，19.12% and 7.35%，and partial productivities of nitrogen increased by 18.95%，32.88% and -1.26%，respectively. Suitable application depth of phosphate fertilizer increased grain weight per spike，yield and harvest index，which all showed P15>P10>P5>P20>CK，the yields of P10 and P15 treatments increased by 18.98% and 32.86% compared with P5 treatment，respectively，and the yield of P20 treatment decreased by 1.27% compared with P5 treatment.In conclusion，15 cm is the optimal depth of phosphorus fertilizer application，which can promote the growth and down lapping of foxtail millet roots，improve the uptake and utilization of nitrogen by roots in soil，promote the accumulation and transportation of dry matter，and increase the yield by 32.86% compared with the shallow application of phosphorus fertilizer at 5 cm.

Key words: Foxtail millet, Phosphorus fertilizer, Application depth, Root, Dry matter accumulation, Nitrogen absorption, Yield

摘要： 采用大田试验，设置5 cm(P5)、10 cm(P10)、15 cm(P15)和20 cm(P20)4个磷肥施用深度，以不施磷肥为对照(CK)，研究磷肥施用深度对谷子根系分布、干物质积累和转运、氮素吸收利用、产量的影响，以期为谷子生产上磷肥的高效利用提供理论基础。结果表明，适当的磷肥施用深度能促进谷子根系生长，提高根长、根表面积和根干质量，整体表现为P15>P10>P5>P20>CK；随着磷肥施用深度的增加，深层土壤中谷子的根长、根表面积和根干质量增加，在20~40 cm土层表现为P20>P15>P10>P5>CK。适当的磷肥深施可以促进谷子干物质积累和转运，相较于P5处理，P10、P15和P20处理成熟期干物质积累量分别提高4.60%、10.29%和0.92%，干物质转移率分别提高6.49%、10.06%和- 20.13%。磷肥深施提高了根系对深层土壤中氮素的吸收和利用，深层土壤尤其是20~40 cm土层中的有效氮含量较P5处理显著降低，P10、P15、P20处理成熟期谷子总氮积累量分别较P5处理提高3.91%、17.85%、5.31%，氮素吸收效率分别提高5.88%、19.12%、7.35%，氮肥偏生产力分别提高18.95%、32.88%、-1.26%。适当的磷肥深施可以提高穗粒质量、产量和收获指数，均表现为P15>P10>P5>P20>CK，P10、P15处理产量分别较P5处理提高18.98%、32.86%，P20处理较P5处理减产1.27%。综上，15 cm为最优磷肥施用深度，可促进谷子根系生长及下扎，提高根系对土壤中氮素的吸收和利用，促进干物质积累及转运，相较于磷肥5 cm浅施增产32.86%。

关键词: 谷子, 磷肥, 施用深度, 根系, 干物质积累, 氮素吸收, 产量