Abstract Agricultural extension services in many peanut (Arachis hypogaea L.)-producing regions recommend that farmers reduce nitrogen (N) fertilization rates, or apply N credits, to crops planted after peanut but do not typically specify how peanut residue management or planting schedules of subsequent crops affect the magnitude of peanut N credits. The objective of this study was to quantify peanut N credits to winter wheat (Triticum aestivum L.) in a conservation tillage cropping system in different subtropical growing environments. A five site-year study was conducted in Florida, USA beginning in 2016. A split-plot experimental design was arranged in which summer crop [peanut, cotton (Gossypium hirsutum L.), and weed-free fallow] was the main plot factor, while N rate (0, 34, 67, and 101 kg N ha−1) to winter wheat was the split plot factor. Peanut and cotton were planted under strip-tillage, while winter wheat was drilled into peanut and cotton residues and weed-free fallow plots without tillage. Although peanut residues accumulated 54–93 kg N ha−1, plant available N at winter wheat planting in the 0–15 cm soil depth range of former peanut plots was only higher than in former cotton or fallow plots for one site-year. A previous peanut crop did not affect winter wheat grain yield, but there were cases of lower grain yield, grain N removal, and agronomic efficiency following cotton relative to peanut depending on site. Nonlinear regression procedures predicted that N rates required to optimize grain yields following peanut would exceed 94 kg N ha−1, further indicating the absence of detectible peanut N credits in this study. These results suggest that assuming peanut provides N credits to subsequent crops in the southeastern USA is not justified and, if assumed, will reduce the productivity of subsequent crops.

中文翻译：

---

在美国东南部的保护性耕作管理下，冬小麦的花生氮信用可以忽略不计

摘要 许多花生 (Arachis hypogaea L.) 产区的农业推广服务建议农民降低氮 (N) 施肥率，或对花生后种植的作物应用 N 信用，但通常不具体说明花生残留管理或种植计划随后的作物影响花生 N 信用的大小。本研究的目的是量化不同亚热带生长环境中保护性耕作系统中冬小麦 (Triticum aestivum L.) 的花生氮信用。从 2016 年开始在美国佛罗里达州进行了为期五年的研究。 安排了一个裂地试验设计，其中夏季作物 [花生、棉花 (Gossypium hirsutum L.) 和无杂草休耕] 是主要的地块因素，而冬小麦的 N 比率（0、34、67 和 101 kg N ha-1）是裂区因子。花生和棉花种植在条耕下，而冬小麦则在花生和棉花残留物和无杂草休耕地进行免耕。尽管花生残留物积累了 54-93 kg N ha-1，但在原花生地块 0-15 cm 土深范围内种植冬小麦的植物有效氮仅比原棉花地或休耕地一年高。前一季花生作物未影响冬小麦籽粒产量，但在不同产地，棉花相对于花生籽粒产量、籽粒氮去除和农艺效率较低。非线性回归程序预测，优化花生后谷物产量所需的 N 比率将超过 94 kg N ha-1，进一步表明本研究中缺乏可检测的花生 N 信用。