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Abstract The aim of this study was to determine how soil bunds affected important soil characteristics based on the soil's reflectance in Aba Gerima, an Ethiopian midland of the Abbay River Basin. Soil samples were collected from 0 to 30 cm of the soil depth in 48 plots for soil texture, pH, organic carbon (OC), total nitrogen (TN), available phosphorus (av. P), and available potassium (av. K). Using a spectroradiometer, we evaluated the reflectance of soils that had been air‐dried, pulverized, and sieved. To locate and forecast the change in soil parameters, we employed regression modeling. We identified and predicted soil properties using the models, which were evaluated by the coefficient of determination (R2) and root mean square error. Soils from bunded plots had less reflection. Higher amounts of clay (61%), OC (2.30%), av. P (13.72 ppm), and av. K (116.55 mg/kg) were found in bunded plots. For calibration data, R2 was 0.93, 0.83, and 0.82 for clay, sand, and OC contents, respectively. Spectroradiometry could therefore complement conventional soil analysis. More study is needed to enhance spectroscopy's prediction performance.

Anionic polyacrylamide (PAM) has the potential to reduce soil erosion through soil conditioning. However, a comprehensive study about its effectiveness especially when applied combined with other amendments have rarely been conducted in the tropical highland climatic conditions, such as in Ethiopia. The study assessed the effectiveness of PAM (P = 40 kg ha−1) alone or integrated with other soil amendments such as gypsum (G = 5 t ha−1), lime (L = 4 t ha−1) and biochar (B = 8 t ha−1) on runoff and soil loss at Aba Gerima watershed in the Upper Blue Nile basin, northwest of Ethiopia, where there is high erosion-caused soil degradation. A total of 79 daily runoff and sediment data were collected from eight runoff plots (1.3m × 4m) with three replications planted with teff (Eragrostis tef) crop for two years (2018 & 2019) rainy seasons. Associated changes in soil physicochemical properties and crop growth parameters were investigated. Treatments reduced seasonal runoff by 12–39% and soil loss by 13–53%. The highest reduction in runoff was observed from P + B and PAM treatments while the highest reduction in soil loss was observed from that of P + L and PAM treatments. Integrating PAM with other amendments improved soil structural stability, moisture content, soil pH (P + L) and organic matter (P + B), leading to favorable environment for crop growth (biomass yield) and reduced runoff and soil erosion. Unlike PAM, biochar and lime amendments may need more time after application to be more effective. Hence continuing the field experiment and studying physico-chemical mechanisms for extended period will better elucidate their single or combined effectiveness over time.

Data from remote sensing devices are essential for monitoring environmental protection practices and estimating crop yields. However, yield estimates in Ethiopia are based on time-consuming surveys. We used Sentinel-2, spectroradiometeric, and ground-truthing data to estimate the grain yield (GY) of two major crops, teff, and finger millet, in Ethiopia's Aba Gerima catchment in 2020 and 2021. At the flowering stage, we performed supervised classification on October Sentinel-2 images and spectral reflectance measurement. We used regression models to identify and predict crop yields, as evaluated by the coefficient of determination (adjusted R2) and root mean square error (RMSE). The enhanced vegetation index (EVI) and normalized-difference vegetation index (NDVI) provided the best fit to the data among the vegetation indices used to predict teff and finger millet GY. Soil bund construction increased the majority of vegetation indices and GY of both crops. We discovered a strong correlation between GY and the satellite EVI and NDVI. However, NDVI and EVI had the greatest influence on teff GY (adjusted R2 = 0.83; RMSE = 0.14 ton/ha), while NDVI had the greatest influence on finger millet GY (adjusted R2 = 0.85; RMSE = 0.24 ton/ha). Teff GY ranged from 0.64 to 2.16 ton/ha for bunded plots and 0.60 to 1.85 ton/ha for non-bunded plots using Sentinel-2 data. Besides, finger millet GY ranged from 1.92 to 2.57 ton/ha for bunded plots and 1.81 to 2.38 ton/ha for non-bunded plots using spectroradiometric data. Our findings show that Sentinel-2- and spectroradiometeric-based monitoring can help farmers manage teff and finger millet to achieve higher yields, more sustainable food production, and better environmental quality in the area. The study's findings revealed a link between VIs and soil management practices in soil ecological systems. Model extrapolation to other areas will necessitate local validation.