Apparent Nitrogen Recovery in Milk and Early Dry Season Nitrous Oxide Emission Factors for Urine Deposited by Dual-Purpose Cattle on Different Soil Types
Apparent Nitrogen Recovery in Milk and Early Dry Season Nitrous Oxide Emission Factors for Urine Deposited by Dual-Purpose Cattle on Different Soil Types
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DOI：
10.3389/fsufs.2020.602657
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发表时间：
2021-01
期刊：
影响因子：
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通讯作者：
Sandra Guisela Durango Morales;Rolando Barahona;D. Bolívar;J. Arango;L. Verchot;N. Chirinda
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文献类型：
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作者：
Sandra Guisela Durango Morales;Rolando Barahona;D. Bolívar;J. Arango;L. Verchot;N. Chirinda
牧场条件影响养分利用效率和沉积排泄物中氮 (N) 的损失。部分氮以一氧化二氮 (N2O) 的形式流失，这是一种强效温室气体。本研究的目的是表征两用牛牛奶中的表观氮回收率，并量化它们在放牧 Megathyrsus maximus cv. 后尿液中的 N2O 排放量。蒙巴萨。对哥伦比亚两个对比地区（卡萨纳雷和大西洋）的草和牛生产的牛奶中的氮含量以及牛奶尿素氮 (MUN) 含量进行了量化。使用康奈尔净碳水化合物和蛋白质系统估算牛的干物质摄入量 (DMI)。我们使用封闭式静态室技术来测量有或没有尿斑的地区土壤中的 N2O 排放量（在大西洋地区 21 天，在卡萨纳雷 35 天）。 Casanare 和 Atlántico 的估计 DMI 值为 11.5 和 11.6 kg DM day−1，产奶量为 6.5 和 5.9 L day−1，牛奶中表观氮回收率为 24% 和 23%，MUN 含量分别为 4.4 和 17.2 mg N dl−1。在卡萨纳雷和大西洋，以尿液形式施入土壤的氮对应的比率为 20 和 64 g N m−2，累积 N2O 净排放量分别为 350 和 20 mg N2O-N m−2。尽管所提供的日粮消化率较低，但牛奶中的氮回收率高于热带条件下奶牛的报告值。 Atlántico 站点的高尿液 N 输入并未导致高 N2O 排放，这表明基于 N 输入的默认方法 1 排放因子 (EF) 会高估 Atlántico 中基于尿液的 N2O 排放量。比较之前在哥伦比亚进行的研究，我们观察到基于尿液的 N2O 排放量存在区域间差异。这一观察结果表明，为了提高估算基于尿液的 N2O 排放量的确定性，哥伦比亚需要转向更加针对特定区域的 Tier 2 EF，并减少对默认 IPCC Tier 1 EF 的依赖。此外，养牛行业采用方法 2 EF 将有助于计算动物饮食对 N2O 清单的影响。
Pasture conditions influence the nutrients use efficiency and nitrogen (N) losses from deposited excreta. Part of the N is lost as nitrous oxide (N2O), a potent greenhouse gas. The objective of this study was to characterize apparent N recovery in milk of dual-purpose cattle and to quantify N2O emissions from the urine they deposit following grazing on Megathyrsus maximus cv. Mombasa. The N content in the grass and the milk produced by the cattle and the milk urea N (MUN) content were quantified in two contrasting regions of Colombia (Casanare and Atlántico). Dry matter intake (DMI) by the cattle was estimated using the Cornell Net Carbohydrate and Protein System. We used a closed static chamber technique to measure N2O emissions from soils in areas with and without urine patches (21 days in Atlántico and 35 Days in Casanare). Estimated DMI values were 11.5 and 11.6 kg DM day−1, milk production was 6.5 and 5.9 L day−1, apparent N recovery in milk was 24 and 23%, and the MUN content was 4.4 and 17.2 mg N dl−1 in Casanare and Atlántico, respectively. N applied to soil in the form of urine corresponded at rates of 20 and 64 g N m−2 and net cumulative N2O emissions were 350 and 20 mg N2O-N m−2 in Casanare and Atlántico, respectively. Despite low digestibility of offered diet, N recovery in milk was above the values reported at dairy cattle in tropical conditions. High urine-N inputs at Atlántico site did not result in high N2O emissions suggesting that the default Tier 1 emission factor (EF) which is based on N inputs would have overestimated urine-based N2O emissions in Atlántico. Comparing previous studies conducted in Colombia, we observed inter-regional differences by urine-based N2O emissions. This observation suggests that to increase certainty in estimating urine-based N2O emissions, Colombia needs to move toward more region-specific Tier 2 EF and reduce its dependence on the default IPCC Tier 1 EF. In addition, the adoption of Tier 2 EF in the cattle sector will facilitate accounting for the effect of animal diets on N2O inventories.