Under temporary economic stress, producers may elect to grow crops without fertilization. However, information is lacking regarding crop and soil response to growing multiple crops without phosphorus (P) and potassium (K) fertilization on claypan soils in the eastern Great Plains. The objective of this study was to determine the effect of utilizing soil‐test P (STP) and soil‐test K (STK) reserves on yield of 5‐yr continuous soybean [Glycine max (L.) Merr.] grown on a claypan soil and on soil‐test values. In the first two low‐yielding years, soybean yield and yield components were unaffected by STP and STK concentrations. In the subsequent three average‐yielding years, soybean yields were up to 0.35 Mg ha⁻¹ less when STP was initially 5 mg kg⁻¹ or STK was initially 57 mg kg⁻¹ than at greater STP or STK. Greater STP increased pods plant⁻¹, whereas greater STK increased pods plant⁻¹, seed pod⁻¹, and seed weight. Even though P and K uptake at R2 (full bloom) did not correlate directly with yields, greater P uptake at R2 in average‐yielding years increased pods plant⁻¹ and greater K uptake at R2 increased seed pod⁻¹. Both STP and STK declined at more than 3 mg kg⁻¹ yr⁻¹ for larger initial STP and 15 mg kg⁻¹ yr⁻¹ for larger initial STK. While using residual soil P and K of varying concentrations in this claypan soil to grow soybeans marginally affected yields, the 5‐yr decline in STP and STK values may greatly affect subsequent sensitive crops and require high rates of fertilization.

中文翻译：

---

利用土壤磷和钾储量在黏土土壤上生产大豆

在暂时的经济压力下，生产者可以选择种植不施肥的作物。但是，缺乏关于东部大平原东部黏土土壤上作物和土壤对多种作物无磷（P）和钾（K）施肥的反应的信息。这项研究的目的是确定利用土壤试验P（STP）和土壤试验K（STK）储备对在平底锅上种植的5年连续大豆[ Glycine max（L.）Merr。]产量的影响。土壤和土壤测试值。在头两个低产年份，大豆产量和产量组成不受STP和STK浓度的影响。在随后的3平均收益年，大豆产率高达0.35镁公顷^-1以下时STP最初5毫克千克^-1或STK最初比更大的STP或STK为57 mg kg ^-1。较高的STP增加了豆荚植物^-1，而较大的STK则增加了豆荚植物^-1，种子荚^-1和种子重量。尽管R2（盛开）的P和K吸收与产量没有直接关系，但平均产量的年份R2的P吸收增加，豆荚植物^-1增加，R2的K吸收增加，种子荚^-1增加。对于较大的初始STP，STP和STK均下降超过3 mg kg ^-1  yr ^-1，而15 mg kg ^-1  yr ^-1对于较大的初始STK。虽然在这种粘土盘土壤中使用不同浓度的残留土壤P和K来种植大豆对产量的影响很小，但STP和STK值连续5年下降可能会严重影响随后的敏感作物，并需要高施肥量。