It remains uncertain how oat ( Avena sativa L.) and hairy vetch ( Vicia villosa Roth.) impact both nitrogen (N) and sulfur (S) recycling in cover crop-maize ( Zea mays L.) systems as well as N and S diagnostic methods in maize. Field trials were conducted at three sites in the southeastern Argentinean Pampas to evaluate the effect of oat, hairy vetch, and bare fallow combined with four N and S fertilization treatments (unfertilized, N-, S-, and NS-fertilized) on maize. Soil N and S content at maize sowing, chlorophyll meter reading (CMR) at silking, and grain yield were determined. Overall, soil NO 3 − -N content (0–60 cm) at maize sowing was hairy vetch > bare fallow > oat, while SO 4 −2 -S content was hairy vetch > bare fallow = oat. Maize yield response to N was predicted from soil NO 3 − -N content ( R 2 = 0.80). The CMR was negatively correlated with cover crop residue quality (carbon (C)/N and C/S ratios). Also, CMR accurately predicted variations in maize grain yield. In the unfertilized treatment, maize yield was hairy vetch > bare fallow > oat, in two of the three sites. There was no yield response to N or S with hairy vetch. Oat and hairy vetch differentially affected N and S recycling in cover crop-maize cropping systems. Soil NO 3 − -N and SO 4 −2 -S content at maize sowing combined with CMR are reliable diagnostic tools to assess maize N and S, allowing for sustainable fertilization management.

中文翻译：

---

覆盖作物 - 玉米系统中的氮和硫回收和诊断

尚不确定燕麦 (Avena sativa L.) 和多毛紫云英 (Vicia villosa Roth.) 如何影响覆盖作物 - 玉米 (Zea mays L.) 系统中的氮 (N) 和硫 (S) 循环以及 N 和 S玉米的诊断方法。在阿根廷东南部潘帕斯草原的三个地点进行了田间试验，以评估燕麦、多毛紫云英和裸露结合四种施氮和施肥处理（未施肥、施氮、施硫和施氮肥）对玉米的影响。测定了玉米播种时的土壤 N 和 S 含量、抽丝时的叶绿素读数 (CMR) 和谷物产量。总体而言，玉米播种时土壤NO 3 - -N 含量（0-60 cm）为紫云英>裸休耕>燕麦，而SO 4 -2 -S含量为紫云英>裸休耕=燕麦。玉米产量对 N 的响应是根据土壤 NO 3 - -N 含量预测的（R 2 = 0.80）。CMR 与覆盖作物残留质量（碳 (C)/N 和 C/S 比）呈负相关。此外，CMR 准确预测了玉米产量的变化。在未施肥处理中，三个地点中的两个地点的玉米产量为有毛野豌豆 > 裸休耕 > 燕麦。有毛紫云英对 N 或 S 没有屈服反应。燕麦和多毛紫云英对覆盖作物 - 玉米种植系统中 N 和 S 循环的影响不同。玉米播种时土壤 NO 3 - -N 和 SO 4 -2 -S 含量与 CMR 相结合是评估玉米 N 和 S 的可靠诊断工具，可实现可持续施肥管理。有毛紫云英对 N 或 S 没有屈服反应。燕麦和多毛紫云英对覆盖作物 - 玉米种植系统中 N 和 S 循环的影响不同。玉米播种时土壤 NO 3 - -N 和 SO 4 -2 -S 含量与 CMR 相结合是评估玉米 N 和 S 的可靠诊断工具，可实现可持续施肥管理。有毛紫云英对 N 或 S 没有屈服反应。燕麦和多毛紫云英对覆盖作物 - 玉米种植系统中 N 和 S 循环的影响不同。玉米播种时土壤 NO 3 - -N 和 SO 4 -2 -S 含量与 CMR 相结合是评估玉米 N 和 S 的可靠诊断工具，可实现可持续施肥管理。