Land-use change (LUC) can impact soil quality. In semi-arid areas of Brazil, impacts of LUC need to be understood for better soil management. This study evaluated the impact of LUC on soil organic carbon (SOC), nitrogen (N), and phosphorus (P) distributions through the soil profile and stocks of a Haplic-Cambisol in the Brazilian Semi-arid region. Three land-use systems (LUS) were investigated: agricultural management (30 years), regeneration under controlled grazing (25 years) after 5 years arable management, and native dry forest. Soil contents of P, total C, total N, and N fractions were used to calculate stocks and their stoichiometric ratios for layers 0–5, 5–10, 10–20, and 20–40 cm. Data from these LUS were compared using Kruskal–Wallis non-parametric tests. Changes to soil microbial biomass reflected the substantially reduced SOC concentration and stock in managed soils compared with that of the natural dry forest area. Total N stock was not affected by LUC, although increases in nitrate and ammonium offset a significantly reduced organic N fraction in the agricultural area. The largest P stock was found in agricultural land, followed by the grazed fallow regeneration site. LUC significantly influenced the stoichiometric ratio of C, N, and P, with the change from Caatinga to agriculture affecting the equilibrium between organic residues’ input and mineralization. LUC resulted in significant changes to C, N, and P stocks, which did not recover to the original values, even after 25 years of regeneration under controlled grazing.

中文翻译：

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土地利用变化改变了巴西半干旱地区 Haplic Cambisol 的碳、氮和磷储量

土地利用变化 (LUC) 会影响土壤质量。在巴西的半干旱地区，需要了解 LUC 的影响以更好地进行土壤管理。本研究通过巴西半干旱地区 Haplic-Cambisol 的土壤剖面和储量评估了 LUC 对土壤有机碳 (SOC)、氮 (N) 和磷 (P) 分布的影响。调查了三个土地利用系统（LUS）：农业管理（30 年）、5 年耕地管理后的受控放牧再生（25 年）和原生旱林。P、总 C、总 N 和 N 组分的土壤含量用于计算 0-5、5-10、10-20 和 20-40 cm 层的储量及其化学计量比。使用 Kruskal-Wallis 非参数检验比较来自这些 LUS 的数据。与自然干旱林区相比，土壤微生物生物量的变化反映了管理土壤中 SOC 浓度和存量的显着降低。总氮储量不受 LUC 的影响，尽管硝酸盐和铵的增加抵消了农业区有机氮含量的显着降低。最大的磷储量在农田中发现，其次是放牧的休耕更新地点。LUC 显着影响 C、N 和 P 的化学计量比，从卡廷加到农业的变化影响有机残留物输入和矿化之间的平衡。LUC 导致 C、N 和 P 库的显着变化，即使在受控放牧的情况下经过 25 年的再生，也没有恢复到原始值。