The Brazilian Cerrado is a large and expanding agricultural frontier, representing a hotspot of land‐use change (LUC) from natural vegetation to farmland. It is known that this type of LUC impacts soil organic matter (SOM) dynamics, particularly labile carbon (C) pools (living and non‐living), decreasing soil health and agricultural sustainability, as well as increasing soil greenhouse gas (GHG) emissions, and accelerating global climate change. In this study, we quantified the changes in the quantity and quality of SOM and GHG fluxes due to changes in land use and cropland management in the Brazilian Cerrado. The land uses studied were native vegetation (NV), pasture (PA) and four croplands, including the following management types: conventional tillage with a single soybean crop (CT), and three no‐tillage systems with two crops cultivated in the same year (i.e., soybean/sorghum (NT_SSo), soybean/millet (NT_SMi) and maize/sorghum (NT_MSo)). Soil and gases were sampled in the rainy season (November, December and January) and dry season (May, July and September). The highest soil C and nitrogen (N) stocks (6.7 kg C m⁻² and 0.5 kg N m⁻², 0–0.3‐m layer) were found under NV. LUC reduced C stocks by 25% in the CT and by 10% in the PA and NT. Soil N stocks were 30% lower in the PA and NT_MSo and 15% lower in the croplands with soybean compared to NV. δ¹³C values clearly distinguished between the C‐origin from NV (−25‰) and that from other land uses (−16‰). Soil (0–0.1 m) under NV also presented higher labile‐C (625 g C m⁻²), microbial‐C (70 g C m⁻²) and microbial‐N (5.5 g N m⁻²), whereas other land uses presented values three times lower. GHG emissions (expressed as C‐equivalent) were highest in the NV (1.2 kg m⁻² year⁻¹), PA (1.3 kg m⁻² year⁻¹) and NT_MSo (0.9 kg m⁻² year⁻¹) and were positively related to the higher SOM turnover in these systems. Our results suggest that in order to maintain SOM, it is necessary to adopt “best” management practices, that provide large plant residue inputs (above‐ and belowground). This can be seen as a pathway to achieving high food production with low GHG emissions.

中文翻译：

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土地利用和耕地管理对巴西塞拉多土壤有机质和温室气体排放的影响

巴西的塞拉多（Cerrado）是一个庞大且不断扩展的农业领域，代表了从自然植被到农田的土地利用变化（LUC）的热点。众所周知，这种类型的LUC影响土壤有机物（SOM）的动力学，特别是不稳定的碳（C）库（活的和非活的），降低土壤健康和农业可持续性以及增加土壤温室气体（GHG）的排放，并加速全球气候变化。在这项研究中，我们量化了巴西Cerrado地区由于土地利用和耕地管理方式变化而导致的SOM和GHG通量的数量和质量变化。研究的土地用途为天然植被（NV），牧场（PA）和4种耕地，包括以下管理类型：单一大豆作物的常规耕作（CT），_SSO），大豆/小米（NT _SMI）和玉米/高粱（NT _MSO））。在雨季（11月，12月和1月）和旱季（5月，7月和9月）对土壤和气体进行了采样。最高土壤C和氮（N）的股票（6.7千克碳米^-2和0.5千克氮米^-2，0-0.3米层）的NV下找到。LUC在CT中减少了25％的C库存，在PA和NT中减少了10％。与NV相比，PA和NT _MSo的土壤氮素存量比大豆减少了30％，农田中的氮素存量减少了15％。δ ¹³ C值的C-原点之间清楚地区分从NV（-25‰）和从其他土地用途（-16‰）。NV下的土壤（0–0.1 m）也表现出较高的不稳定度（625 g C m ^-2），微生物-C（70 g C m ^-2）和微生物-N（5.5 g N m ^-2），而其他土地利用的价值低三倍。内华达州（1.2 kg m - ²年^-1），PA（1.3 kg m - ²年^-1）和NT _MSo（0.9 kg m - ²年^-1）的温室气体排放量（以C当量表示）最高，与这些系统中较高的SOM营业额成正比。我们的结果表明，为了维持SOM，有必要采用“最佳”管理实践，该实践提供了大量的工厂残留物投入（地上和地下）。这可以看作是实现低温室气体排放的高粮食生产的途径。