Information on greenhouse gas (GHG) emissions in organic crop production using sheep (Ovis aries L.) grazing to control weeds is lacking. We examined GHG emissions from May 2013 to April 2016 under wheat (Triticum aestivum L.)-based sequences in organic and conventional crop productions in the northern Great Plains. Organic crop production included sheep grazing to control weeds without N application (OCP) and conventional crop production included herbicides, pesticides, and N applications (CCP). Cropping sequences in a 5-yr rotation of safflower (Carthamus tinctorius L.)/sweetclover cover crop [Melilotus officinalis (L.) Lam.]–sweetclover cover crop–winter wheat–lentil (Lens culinaris L.)–winter wheat were lentil after winter wheat (L–W), winter wheat after sweetclover cover crop (W–C), and winter wheat after lentil (W–L). The CO₂ and N₂O fluxes peaked immediately after tillage, planting, fertilization, intense precipitation, and snowmelt, but CH₄ uptake increased in the autumn. Cumulative CO₂ flux was lower with OCP than CCP for W–C in 2014–2015 and for W–L in 2015–2016. Cumulative N₂O flux was also lower with OCP than CCP for W–C in 2014–2015, but was greater with OCP than CCP for L–W in 2015–2016. Treatments did not affect cumulative CH₄ flux. The global warming potential (GWP) was lower with OCP than CCP for W–C in 2014–2015 and for W–L in 2015–2016. Organic crop production using sheep grazing with no chemical input reduced GHG emissions under winter wheat following clover cover crop or lentil compared with conventional crop production using chemical inputs under lentil following winter wheat.

中文翻译：

---

以冬小麦为基础的有机和常规作物生产的温室气体排放

缺乏关于使用绵羊 ( Ovis aries L.) 放牧来控制杂草的有机作物生产中温室气体 (GHG) 排放的信息。我们研究了 2013 年 5 月至 2016 年 4 月在大平原北部有机和常规作物生产中基于小麦 ( Triticum aestivum L.) 的序列下的温室气体排放。有机作物生产包括放牧以控制不施氮 (OCP) 的杂草，常规作物生产包括使用除草剂、杀虫剂和施氮 (CCP)。红花（Carthamus tinctorius L.）/甜菜覆盖作物 [ Melilotus officinalis (L.) Lam.]-甜菜覆盖作物 - 冬小麦 - 扁豆（Lens culinarisL.)-冬小麦在冬小麦之后是扁豆（L-W），在甜三叶草覆盖作物之后是冬小麦（W-C），在扁豆之后是冬小麦（W-L）。CO ₂和N ₂ O通量在耕作、种植、施肥、强降水和融雪后立即达到峰值，但秋季CH ₄吸收增加。2014-2015 年 W-C 和 2015-2016 年 W-L 使用 OCP 的累积 CO ₂通量低于 CCP。2014-2015 年 W-C 的 OCP累积 N ₂ O 通量也低于 CCP，但 2015-2016 年 L-W 的 OCP累积 N ₂ O 通量高于 CCP。处理不影响累积 CH ₄通量。2014-2015 年 W-C 和 2015-2016 年 W-L 使用 OCP 的全球变暖潜能值 (GWP) 低于 CCP。与在冬小麦种植后种植小扁豆种植化学品的传统作物生产相比，采用无化学品投入的绵羊放牧有机作物生产减少了种植三叶草或小扁豆种植后冬小麦种植的温室气体排放。