High-yielding corn response to applied phosphorus, potassium, and sulfur in Nebraska

Nutrient management recommendations may change as yield levels and efficiency of crop production increase. Recommendations for P, K, and S were evaluated using results from 34 irrigated corn (Zea mays L.) trials conducted in diverse situations across Nebraska. The mean yield was 14.7 Mg ha−1 with adequate fertilizer applied. The median harvest index values were 0.52, 0.89, 0.15, and 0.56 for biomass, P, K, and S, respectively. Median grain yields were 372, 49, and 613 kg kg−1 of aboveground plant uptake of P, K, and S, respectively. The estimated critical Bray-1 P level for corn response to 20 kg P ha−1 was 20 mg kg−1 when the previous crop was corn compared with 10 mg kg−1 when corn followed soybean [Glycine max (L.) Merr.]. Soil test K was generally high with only three site-years <125 mg kg−1 Over all trials, application of 40 kg K ha−1 resulted in a 0.2 Mg ha−1 mean grain yield decrease. Application of 22 kg S ha−1 did not result in significant yield increase in any trial. Soil test results accounted for twice as much variation in nutrient uptake when soil organic matter (SOM) and pH were considered in addition to the soil test nutrient values. The results indicate a need to revise the current recommendation for P, to maintain the current K and S recommendations, and to use SOM and pH in addition to soil test nutrient values in estimating applied nutrient requirements for irrigated high yield corn production.

随着作物产量水平与生产效率的提升，养分管理推荐方案可能随之调整。本研究针对磷（P）、钾（K）、硫（S）的推荐方案，基于美国内布拉斯加州不同种植条件下开展的34项灌溉玉米（Zea mays L.）试验结果进行了评估。试验中施用足量肥料时的平均产量为14.7 Mg·ha⁻¹。生物量、磷、钾、硫的收获指数（Harvest Index）中位数分别为0.52、0.89、0.15与0.56；单位地上部植株吸收的磷、钾、硫对应的籽粒产量中位数分别为372、49与613 kg·kg⁻¹。当玉米前茬为玉米时，其响应20 kg P·ha⁻¹施用量的Bray-1磷（Bray-1 P）临界估计值为20 mg·kg⁻¹；而当玉米前茬为大豆[Glycine max (L.) Merr.]时，该临界值为10 mg·kg⁻¹。整体而言土壤速效钾（Soil Test K）含量普遍较高，仅3个试验点年的土壤速效钾含量低于125 mg·kg⁻¹。综合所有试验来看，施用40 kg K·ha⁻¹会使籽粒平均产量降低0.2 Mg·ha⁻¹；而施用22 kg S·ha⁻¹在所有试验中均未带来显著的籽粒产量提升。相较于仅纳入土壤测试养分含量，当同时考虑土壤有机质（Soil Organic Matter, SOM）与酸碱度（pH）时，土壤测试结果对养分吸收量变异的解释度提升了一倍。本研究结果表明，亟需修订当前的磷养分推荐方案，维持现有钾、硫养分推荐方案，并在估算灌溉高产玉米生产的养分施用量时，同时纳入土壤有机质、酸碱度与土壤测试养分含量指标。