Pasture fertilization may influence the subsequent corn crop in integrated crop-livestock systems, but few tools exist to assess the likelihood and magnitude of this carryover effect. Our goals were to determine whether a previous pasture with N fertilization could supply adequate N nutrition to a succeeding corn crop and affect its P and K nutrition using the concept of N dilution curve and relationships between N, P, and K in corn shoot biomass. The experiment consisted in a winter grazed pasture followed by a corn crop in summer. Treatments were N fertilization of a black oat (Avena strigosa) winter pasture (0 and 200 kg N ha⁻¹) as main plots and four sidedress N fertilization rates (0, 100, 200, and 300 kg N ha⁻¹) applied to corn as sub-plots in a randomized complete block design with split-plot restriction. The N nutrition index, that is, the ratio of observed shoot N concentrations to critical N concentration determined by a critical N dilution curve, adequately identified situations of deficient N nutrition in corn following a pasture with or without N fertilization. This carryover effect from a winter pasture should therefore be accounted for in N fertilizer recommendations for corn in tropical soils. Corn P nutrition, based on critical P concentrations derived as a function of N concentration, was nearly optimal when no N was applied to the pasture, but it was less than optimal when N was applied. Although no critical K curves have been published, our results confirm that the relationship between shoot K and N concentrations varies with the level of N nutrition as does the relationship between shoot P and N concentrations. Our results confirm that the concept of critical N and P concentrations serves as a useful reference to assess the status of N and P nutrition during corn growth in tropical soils with the potential to improve nutrient management of corn following a pasture in an integrated crop-livestock system.

牧场施肥可能会影响综合作物 - 牲畜系统中随后的玉米作物，但很少有工具可以评估这种遗留效应的可能性和程度。我们的目标是使用 N 稀释曲线的概念以及玉米芽生物量中 N、P 和 K 之间的关系，确定先前施氮肥的牧场是否可以为后继玉米作物提供足够的 N 营养并影响其 P 和 K 营养。该实验包括在冬季放牧的牧场，然后在夏季种植玉米。处理是以黑燕麦 ( Avena strigosa ) 冬季牧场( 0 和 200 kg N ha ^-1 ) 作为主要地块的施氮肥和四种副施氮肥率 (0、100、200 和 300 kg N ha ^{-1 )}) 在具有裂区限制的随机完整区组设计中作为子区应用于玉米。N 营养指数，即观察到的枝条 N 浓度与由临界 N 稀释曲线确定的临界 N 浓度的比率，充分确定了在施肥或不施氮的牧场后玉米中缺乏 N 营养的情况。因此，冬季牧场的这种结转效应应在热带土壤玉米的氮肥建议中加以考虑。根据作为 N 浓度函数得出的临界 P 浓度，玉米 P 营养在牧场不施氮时几乎是最佳的，但在施氮时则不太理想。虽然没有发表临界 K 曲线，我们的结果证实，地上部 K 和 N 浓度之间的关系随着 N 营养水平的变化而变化，就像地上部 P 和 N 浓度之间的关系一样。我们的研究结果证实，临界 N 和 P 浓度的概念可作为评估热带土壤中玉米生长过程中 N 和 P 营养状况的有用参考，具有改善作物畜牧综合牧场后玉米养分管理的潜力系统。