In this study, we measured nitrous oxide (N2O) emissions from plots of fall-planted hairy vetch (HV, Vicia villosa) grown as a green nitrogen (N) source for following summer forage crabgrass (Digitaria sanguinalis). Two treatments were compared: (i) HV grown solely as green manure where all biomass was incorporated by tillage, and (ii) harvesting of aboveground HV biomass prior to planting of crabgrass. Fluxes of N2O were measured with closed chamber systems on 27 dates during a 2-month growth period of crabgrass after the termination of HV in early May. At termination, the average aboveground biomass yield of HV was 4.6 Mg ha−1 with 146 kg N ha−1 content. The N2O emissions were as high as 66 g N2O-N ha−1 day−1 on day 1 after HV incorporation, but reached close to zero within a week. Emissions of N2O increased with subsequent rainfall and irrigation events from both treatments but emission peaks were not observed during the rapid growth of crabgrass. Two-month cumulative emission of N2O (mean ± s.e., n = 4) from HV incorporated plots (921 ± 120 g N2O-N ha−1) was three times (P < 0.05) of HV harvested plots (326 ± 30 g N2O-N ha−1). However, crabgrass biomass yields, N concentrations and total biomass N uptake were decreased significantly by harvesting HV. In conclusion, the results suggested that whereas removal of HV biomass for use as forage may significantly reduce N2O emissions, quantity and quality of the following recipient crops may be constrained.

中文翻译：

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基于毛茸茸的紫云英绿肥的掺入和收获管理影响一氧化二氮排放

在本研究中，我们测量了一氧化二氮（N2O) 秋季种植的多毛紫云英 (HV,紫花苜蓿) 作为绿色氮 (N) 来源种植，用于随后的夏季牧草马唐 (血楹）。比较了两种处理：(i) HV 仅作为绿肥种植，其中所有生物质都通过耕作结合，以及 (ii) 在种植马唐之前收获地上 HV 生物质。N的通量2在 5 月初 HV 终止后的 2 个月马唐生长期内，用密闭室系统在 27 个日期测量 O。终止时，HV 的平均地上生物量产量为 4.6 Mg ha-1含 146 kg N ha-1内容。然后2O 排放量高达 66 g N2开哈-1日-1在 HV 并入后的第 1 天，但在一周内接近于零。N的排放2随着随后的降雨和两种处理的灌溉事件，O 增加，但在马唐快速生长期间未观察到排放峰值。N的两个月累积排放量2O（平均值±瑟,n= 4) 来自 HV 合并地块 (921 ± 120 g N2开哈-1) 是三倍 (磷< 0.05) HV 收获地块 (326 ± 30 g N2开哈-1）。然而，收获 HV 显着降低了马唐生物量产量、N 浓度和总生物量 N 吸收。总之，结果表明，去除用作草料的 HV 生物质可能会显着降低 N2以下接收作物的 O 排放、数量和质量可能会受到限制。