Soil acidity is a major land degradation issue in sub-Saharan Africa, severely constraining regional agricultural productivity and threatening food security. In Ethiopia, nearly half of the rainfed agricultural land is affected by soil acidity, with about 12% classified as strongly to extremely acidic (pH < 5.5). As an important agricultural region in Ethiopia, the Upper Blue Nile Basin faces a particularly prominent soil acidity problem. Current soil management strategies mostly adopt a top-down approach, prioritizing scientific interventions such as lime application to mitigate soil acidity, but these strategies have limited adaptability to local conditions. Although Ethiopian farmers possess generations of accumulated soil knowledge, this knowledge has long been excluded from mainstream agricultural policy and research, and academic research on farmers’ specific perceptions of soil acidity remains limited. Most related studies in Ethiopia have focused on the effectiveness of lime in mitigating soil acidity, often neglecting farmers’ traditional adaptive strategies and the similarities and differences between these strategies and scientific assessments.
Recently, the team led by Belstie LULIE at the College of Agriculture and Environmental Sciences, Bahir Dar University, Ethiopia, published a research paper titled “Integrating farmer perceptions and scientific assessments of soil acidity in the Upper Blue Nile Basin, Ethiopia” in ENGINEERING Agriculture (DOI: 10.15302/J-FASE-2026690), an ENGINEERING cluster journal of the Chinese Academy of Engineering. The study focused on three key objectives: assessing farmers’ perceptions of the causes and widespread impacts of soil acidity, documenting the adaptive measures farmers have taken to mitigate the effects of soil acidity, and linking farmer perceptions with scientific assessments of cultivated soil, aiming to provide scientific support for building more inclusive and effective soil management policies.
The research team used a cross-sectional household survey design, conducted in 2022 in three kebeles (the smallest local administrative units) in the Amhara Region, supplemented by field reconnaissance and soil sampling and testing. Before the formal survey, the team conducted a rapid rural appraisal during the pre-survey phase and a pilot survey of 50 people. A multistage sampling method was used to select the study areas and respondents: in the first stage, three districts—Machakel, Baso Liben, and Banja—were selected based on their soil acidity profiles; in the second stage, one kebele was randomly selected from each district, namely Debre Kelemua, Limichim, and Sankit Lidet; subsequently, a total of 292 households were randomly selected from the three kebeles (96 from Debre Kelemua, 96 from Limichim, and 100 from Sankit Lidet).
Soil samples were collected using a stratified random method. Based on questionnaire responses, farmers were grouped into three levels of soil acidity perception: high (n = 67), medium (n = 194), and low (n = 31). On this basis, a total of 146 composite soil samples were collected, this stratified sampling design ensured representative coverage across the gradient of farmer-perceived soil acidity and enabled precise comparison with laboratory-measured soil pH (H₂O) and Munsell soil color classification.
The results showed that farmers generally identified yield reduction (> 97%) and stunted crop growth (> 90%) as the most prominent indicators of soil acidity. Farmers considered the top three causes of soil acidity to be lack of crop rotation, poor field management (continuous cropping and soil compaction), and inadequate soil reclamation measures (insufficient lime application, complete removal of crop residues, and poor organic fertilizer management). For farmland judged by farmers as having high soil acidity, the main causes shifted to lack of crop rotation, absence of fallow periods, and poor field management. For farmland judged by farmers as having medium or low soil acidity, more than half of the respondents attributed it to heavy rainfall and continuous use of mineral fertilizers.
For soil acidity, farmers’ subjective classifications were significantly correlated with laboratory-measured soil pH. Laboratory results showed that many fields were classified as very strongly to extremely acidic, and there was a discrepancy between farmers’ subjective perceptions and measured pH values. The research team pointed out that the high, medium, and low categories assigned by farmers represent a relative severity gradient within an overall acidic soil environment, rather than a precise mapping to pH thresholds. This explains why laboratory measurements often showed that fields judged by farmers as “low acidity” were often more severely acidified.
Regarding soil management strategies, farmers widely adopted organic fertilizer application, planting bitter white lupin, and retaining crop residues. In addition to these main measures, crop rotation was implemented on more than 70% of farmland subjectively judged by farmers as having medium and high acidity. About two-thirds of the farmland had soil conservation structures established. Lime application was inconsistent: nearly half of the farmers did not apply lime, with a higher proportion of non-application in the low-acidity group. Among farmers who applied lime, 13% applied the full recommended rate once every 5 years, and 28% applied the full recommended rate once every 3 years; in the high-acidity group, about 45% of farmers followed a three-year cycle. Organic fertilizer was applied almost universally, with compost being the most common; animal manure was widely applied in medium-acidity areas, while green manure (mainly bitter white lupin) was used more frequently in medium- and high-acidity fields.
The study concluded that local farmers have a high level of awareness of soil acidity but rely on late-stage crop symptoms, which limits proactive management, highlighting an urgent need for rapid soil testing tools. Farmers’ attributions are consistent with scientific findings, and rotation with acid-tolerant crops and increased organic fertilizer application can mitigate acidity. Farmers’ soil acidity classifications represent a relative severity gradient; integrating empirical soil testing with farmer knowledge can improve the precision of management decisions. The study recommends promoting affordable and accessible soil testing tools, rotation with acid-tolerant species, organic amendments, optimized lime application guidance, integration of farmer perceptions with scientific assessments, introduction of alternative legume rotations, planting of nitrogen-fixing trees, and fostering participatory research.
DOI: 10.15302/J-FASE-2026690