Field experiments were conducted in Wisconsin for 3 years on irrigated sandy and silt loam soils in an attempt to better calibrate potato phosphorus (P) needs and to determine which of several P fertilizer placements/timings were best for crop yield and quality or could improve P fertilizer use efficiency. In 2 of 3 years at both locations, positive yield and tuber quality responses were seen with phosphate rates ranging from 45 to 200 kg P₂O₅ ha⁻¹ on the sand and 124 kg > 224 kg P₂O₅ ha⁻¹ on the silt loam. Row placement improved P fertilizer use efficiency on the sand but not on the silt loam. In-season P applications improved plant P concentrations, but did not always result in tuber yield or quality responses, although this method may be effective as a rescue treatment. Early season (~35 days after emergence, dae) petiole P analysis was useful for predicting P sufficiency with a critical level of 0.35% P. Later sampling (> 50 dae) did not adequately separate responsive from non-responsive treatments. Based on this research, row-placed P at modest rates (about 100 kg P₂O₅ ha⁻¹) is recommended on sandy soils, whereas on the medium-textured soil all placement/timings performed similarly except the in-season treatment. A higher rate was needed (~160 kg P₂O₅ ha⁻¹) on this soil to optimize yield and quality.

中文翻译：

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马铃薯上肥料磷速与定位/授时的相互作用

在威斯康星州的灌溉沙质和粉质壤土上进行了为期三年的田间试验，以试图更好地校准马铃薯的磷（P）需求，并确定几种磷肥施用方式/时机中哪一种对作物的产量和质量最有效或可以改善磷肥料使用效率。在这两个位置的三年中的2年中，在沙子上的磷酸盐速率范围为45至200 kg P ₂ O ₅ ha ^-1和124 kg  >  224 kg P ₂ O ₅ ha ^-1时，看到了积极的产量和块茎质量响应。在粉壤土上。行放置提高了沙子上磷肥的使用效率，但对淤泥壤土而言却没有。季节性施磷可提高植物磷的浓度，但并不总是导致块茎产量或质量响应，尽管这种方法可能可以有效地挽救生命。早期（出苗后约35天，dae）叶柄P分析可用于预测P的临界水平为0.35％P的充足性。后期采样（> 50 dae）不能将反应性与非反应性治疗充分分开。根据这项研究，以中等速率（约100 kg P ₂ O ₅ ha ^-1建议在沙质土壤上使用），而在中等质地的土壤上，除按季节处理外，所有放置/调整均以类似方式进行。在这种土壤上需要更高的比率（〜160 kg P ₂ O ₅ ha ^-1）以优化产量和质量。