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Agricultural sustainability and land degradation can be monitored through studying soil nutrient dynamics. This study was conducted to investigate the balance and stocks of nitrogen (N) and phosphorus (P) under major land use types and land management (LM) practices in three contrasting agroecological environments in Ethiopia. We employed a nutrient monitoring approach and assessed soil N and P inputs and outputs at watershed and plot scales. Field data were collected from 72 sites representative of the major land uses of the three watersheds for the watershed scale analysis. In addition to the watershed data, 16 experimental runoff plots were established and the response of nutrient balances to improved LM practices for the major land uses, including cropland with three treatments (control, farmyard manure [FYM] and soil bund), grazing land with three treatments (control, exclosure and FYM + exclosure) and bushland with two treatments (control and exclosure). Nutrient balances, flows and stocks varied significantly among agroecological settings, land-use types and LM practices. Severe and negative N balances were found in all agroecological environments, with midland (-70.8) > highland (-61.7) > lowland (-50.3 kg ha-1 yr-1), whereas slightly positive P balances were found in all agro-ecosystems. As a result, the midland (4.2% yr-1) and highland (2.1% yr-1) sites had greater N depletion rates than the lowland site (1.0% yr-1). Our results also demonstrated that applied LM practices improved N balances: by 32%-40% in cropland through FYM and mineral fertilizer, by 7%-18% in grazing land via FYM and exclosure, and by 6%-36% in degraded bushland via exclosure, implying that, implementing FYM and mineral fertilizer for cropland and implementing FYM with exclosure on non-croplands can reverse nutrient depletion in the study sites and in other areas having similar agroecological conditions. [ABSTRACT FROM AUTHOR]

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. Core Ideas: Soil bunds improved the clay, silt, organic carbon, and potassium contents of soils.Bunded soils recorded less reflectance.Low soil reflectance indices show increased soil quality.Spectroscopy could better characterize soils as compared to convectional one. [ABSTRACT FROM AUTHOR]