Regasa Abu, Haile Wassie, Abera Girma
College of Agriculture and Natural Resource, Dambi Dollo University, Dambi Dollo, Ethiopia.
College of Agriculture, Hawassa University, Hawassa, Ethiopia.
Sci Rep. 2025 Aug 27;15(1):31565. doi: 10.1038/s41598-025-13597-w.
Soil acidification is a critical global challenge that threatens agricultural productivity by limiting nutrient availability and degrading agroecosystems. In Ethiopia, a significant portion of arable land suffers from soil acidity, particularly in the mid and highland areas, posing serious constraints on crop yields. Assessing soil acidity extent across different land uses, soil types, and altitude gradients is essential for managing its spread and mitigating its impact on agroecosystems. This study examined the variation in soil acidity across land uses (coffee farms vs. croplands), soil types (Nitisols vs. Cambisols), and elevation (1500-2346 m.a.s.l.) in the Sayo District, western Ethiopia. A total of 78 composite soil samples (48 from Nitisols and 30 from Cambisols) were collected and analyzed for selected physicochemical properties. Results showed that with increasing elevation, soils became sandier (sand content rose from 31.7 to 47.5% in Nitisols) and less fertile, with clay content, organic matter (OM), total nitrogen (TN), and available phosphorus (Av. P) all declining. Soil pH decreased significantly with altitude indicating greater acidity (dropping from 5.47 to 4.86 in Nitisols and from 5.58 to 5.21 in Cambisols), while exchangeable acidity and aluminum toxicity increased, especially in croplands. Bulk density also rose with altitude and was higher in croplands (1.28-1.29 g/cm) than in coffee farms (1.13-1.16 g/cm), reflecting compaction from cultivation. Coffee farms consistently maintained higher OM (5.50-6.00%), TN (0.28%), Av. P (6.47-11.14 mg/kg), and cation exchange capacity (CEC) greater than in croplands due to organic inputs and reduced soil disturbance. Nitisols had lower sand content, pH, and Av. P, but higher clay content and exchangeable acidity than Cambisols. The significant interaction between elevation and land use underscores how both factors jointly intensify soil acidification and fertility decline. These findings highlight the urgent need for sustainable soil management strategies to mitigate acidification, enhance productivity, and preserve agroecosystem resilience in mid and highland farming systems.
土壤酸化是一项严峻的全球性挑战，它通过限制养分有效性和破坏农业生态系统来威胁农业生产力。在埃塞俄比亚，很大一部分耕地存在土壤酸化问题，尤其是在中部和高地地区，这对作物产量构成了严重限制。评估不同土地利用方式、土壤类型和海拔梯度下的土壤酸化程度，对于控制其蔓延并减轻其对农业生态系统的影响至关重要。本研究考察了埃塞俄比亚西部萨约区不同土地利用方式（咖啡种植园与农田）、土壤类型（铁铝土与雏形土）和海拔（1500 - 2346米海拔）下土壤酸化的变化情况。总共采集了78个混合土壤样本（48个来自铁铝土，30个来自雏形土），并对选定的理化性质进行了分析。结果表明，随着海拔升高，土壤变得更沙质化（铁铝土中的砂含量从31.7%升至47.5%）且肥力下降，黏粒含量、有机质（OM）、全氮（TN）和有效磷（Av. P）均下降。土壤pH值随海拔显著降低，表明酸性增强（铁铝土中从5.47降至4.86，雏形土中从5.58降至5.21），而交换性酸度和铝毒性增加，尤其是在农田中。容重也随海拔升高，且农田中的容重（1.28 - 1.29克/立方厘米）高于咖啡种植园（1.13 - 1.16克/立方厘米），这反映了耕作造成的压实。由于有机投入和较少的土壤扰动，咖啡种植园始终保持着比农田更高的有机质（5.50 - 6.00%）、全氮（0.28%）、有效磷（6.47 - 11.14毫克/千克）以及阳离子交换量（CEC）。铁铝土的砂含量、pH值和有效磷较低，但黏粒含量和交换性酸度高于雏形土。海拔与土地利用之间的显著相互作用突出了这两个因素如何共同加剧土壤酸化和肥力下降。这些发现凸显了迫切需要采取可持续的土壤管理策略，以减轻酸化、提高生产力并保持中部和高地农业系统中农业生态系统的恢复力。
