In the Brazilian Amazon, nitrogen input strategies are required to maintain forage–livestock systems productivity. However, greenhouse gases (GHG) emissions mitigation from tropical soils is also a global demand. This research aims to assess productivity and nitrous oxide (N₂O) emissions from Oxisol cultivated with Marandu palisade grass (Brachiaria brizantha [Hochst. Ex A.Rich.] Stapf) submitted to nitrogen (N) input strategies (N fertilization and biological N fixation) in the Brazilian Amazon. The treatments were the following: control (unfertilized); U40 (fertilized with 40 kg N/ha as urea); U80 (fertilized with 80 kg N/ha as urea); AS40 (fertilized with 40 kg N/ha as ammonium sulfate); AS80 (fertilized with 80 kg N/ha as ammonium sulfate); and IAB (inoculated with Azospirillum brasilense). From January to March 2016, soil N₂O emission, forage accumulation (FA) and relative emission (RE) were assessed during two 28‐day cycles. The FA was greater in the U80 and AS80 than in control and IAB. The highest peaks of soil N₂O flux occurred from 4 to 7 days after N fertilization, primarily in the highest N rates treatments. Overall, 40 kg N/ha resulted in higher N₂O flux than control and IAB, which were lower than 80 kg N/ha regardless of the N source. The lowest fluxes occurred in the control and IAB (below 20 μg N‐N₂O m⁻² hr⁻¹). All of the emission factors (EF) calculated for both fertilizers and rates were lower than 0.35%, which is below the 1% established by the IPCC. Our results indicate the need for discussion of the EF in the pasture intensification to contribute to avoid deforestation and mitigating emissions. The inputs of 40 kg N/ha per application with urea or ammonium sulfate, due to the low EF and RE, are recommended as a pasture N input strategy in the Brazilian Amazon.

中文翻译：

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提交给N种输入策略的巴西亚马逊草料-畜牧系统中的一氧化二氮排放量和草料积累

在巴西的亚马逊地区，需要采用氮输入策略来维持饲草-牲畜系统的生产力。然而，缓解热带土壤温室气体排放也是全球需求。本研究旨在评估提交给氮（N）输入策略（氮肥和生物氮）的Marandu木栅草（Brachiaria brizantha [ Hochst。Ex A.Rich。] Stapf）种植的Oxisol的生产力和一氧化二氮（N ₂ O）排放。固定）在巴西亚马逊。处理方法如下：对照（未受精）；U40（以40 kg N / ha作为尿素施肥）；U80（以80千克N / ha作为尿素施肥）；AS40（以40千克氮/公顷的硫酸铵施肥）；AS80（以80千克N / ha的硫酸铵施肥）; 和IAB（接种巴西固氮螺菌（Azospirillum brasilense）。从2016年1月至2016年3月，在两个28天的周期内评估了土壤N ₂ O排放，饲料积累（FA）和相对排放（RE）。U80和AS80中的FA大于对照和IAB中的FA。施氮后4至7天，土壤N ₂ O通量的最高峰出现在土壤中，这主要是在施氮量最高的土壤中。总体而言，40 kg N / ha的N ₂ O通量高于对照和IAB，无论N源如何，均低于80 kg N / ha。对照和IAB中发生的通量最低（低于20μgN‐N ₂ O m ^-2  hr ^-1）。为肥料和比率计算的所有排放因子（EF）均低于0.35％，低于IPCC确定的1％。我们的结果表明，需要在集约化牧场中讨论EF，以有助于避免森林砍伐和减少排放。在巴西亚马逊地区，由于EF和RE较低，建议每次施用尿素或硫酸铵的氮素输入量为40 kg N / ha，作为牧场氮素输入策略。