As classical soil analysis is time-consuming and expensive, there is a growing demand for visible, near-infrared, and short-wave infrared (Vis-NIR-SWIR, wavelength 350–2500 nm) spectroscopy to predict soil properties. The objectives of this study were to investigate the effects of soil bunds on key soil properties and to develop regression models based on the Vis-NIR-SWIR spectral reflectance of soils in Aba Gerima, Ethiopia. Soil samples were collected from the 0–30 cm soil layer in 48 experimental teff (Eragrostis tef) plots and analysed for soil texture, pH, organic carbon (OC), total nitrogen (TN), available phosphorus (av. P), and potassium (av. K). We measured reflectance from air-dried, ground, and sieved soils with a FieldSpec 4 Spectroradiometer. We used regression models to identify and predict soil properties, as assessed by the coefficient of determination (R2), root mean square error (RMSE), bias, and ratio of performance to deviation (RPD). The results showed high variability (CV ≥ 35%) and substantial variation (P < 0.05 to P < 0.001) in soil texture, OC, and av. P in the catchment. Soil reflectance was lower from bunded plots. The pre-processing techniques, including multiplicative scatter correction, median filter, and Gaussian filter for OC, clay, and sand, respectively were used to transform the soil reflectance. Statistical results were: R2 = 0.71, RPD = 8.13 and bias = 0.12 for OC; R2 = 0.93, RPD = 2.21, bias = 0.94 for clay; and R2 = 0.85 with RPD = 7.54 and bias = 0.0.31 for sand with validation dataset. However, care is essential before applying the models to other regions. In conclusion, the findings of this study suggest spectroradiometry can supplement classical soil analysis. However, more research is needed to increase the prediction performance of Vis-NIR-SWIR reflectance spectroscopy to advance soil management interventions.

Polyacrylamide (PAM) mitigates soil nutrient depletion and increases nutrient utilization; however, the effect of PAM combined with other amendments have not been tested much under field condition. The objective of our study was, therefore, to identify the best combination of amendments that can improve soil nitrogen (N) and phosphorus (P) balances while maximizing utilization efficiency and profitability under teff cultivation. A field experiment was carried out for 2 years in the midland agroecology of Ethiopia. A total of 24 experimental plots were designed using RCBD with three replications. The treatments were PAM (40 kg ha À1 ), biochar (B = 8 t ha À1 ), lime (L = 4 t ha À1 ), gypsum (G = 5 t ha À1 ), PAM+B, PAM+L, PAM+G, and a control.N and P inflows from atmospheric deposition, biological fixation, and fertilizers; and outflows by water erosion, leaching, gaseous emissions, and harvested products were monitored in all plots via NUTrient MONitoring approach. Results showed that all the applied soil amendments improved nutrient balances (8-134%) compared with the control. Of the measured outflows, harvested products (43-60%) and water erosion (14-31%) were the major contributors to N depletion, followed by leaching (15-23%) and gaseous emissions (11-13%). Among the soil amendments, PAM+L appreciably reduced P loss from water erosion (61%); and N losses from erosion, leaching, and emissions by 55, 10, and 3%, respectively; and increased N use efficiency by 31% compared with the control. Moreover, PAM+L provided a net benefit much higher compared with others. Thus, application of PAM+L would be an effective strategy for sustainable agriculture, especially in acidic and degraded dryland areas.

The temporal dynamics of soil respiration change in response to different land management practices is not well documented. This study investigated the effects of soil bunds on the monthly and diurnal dynamics of soil respiration rates in the highlands of the Upper Blue Nile basin in Ethiopia. Six plots (with and without soil bunds, three replicates) were used for measurement of seasonal soil respiration, and eighteen plots were used for measurement of diurnal soil respiration. We collected seasonal variation data on a monthly basis from September 2020 to August 2021. Diurnal soil respiration data were collected four times daily (5 a.m., 11 a.m., 5 p.m., and 11 p.m.) for two weeks from 16-29 September 2021. A Wilcoxon signed-rank test showed that seasonal soil respiration rates differed signi cantly (p < 0.05) between plots with and without soil bunds in all seasons. In plots with soil bunds, seasonal soil respiration rates were lowest in February (1.89 ± 0.3 µmol CO 2 m − 2 s − 1 , mean ± SE) and highest in October (14.54 ± 0.5 µmol CO 2 m − 2 s − 1 ). Diurnal soil respiration rate was signi cantly (p < 0.05) higher at 11 a.m. than at other times, and was lowest at 5 a.m. Both soil temperature and moisture signi cantly affected seasonal variation in soil respiration. Diurnal variation in soil respiration was signi cantly affected by soil temperature but not by soil moisture. Further study is required to explore how differences in soil microorganisms between different land management practices affect soil respiration rates.

Mitigating soil nutrient depletion and increasing utilization efficiency is a prerequisite of sustainable agriculture. Therefore, a field experiment was carried out for 2 years in the midland agroecology of Ethiopia, to identify soil amendment types that can improved soil nitrogen (N) and phosphorus (P) balances at the same time maximize utilization efficiency and profitability under teff cultivation. Using RCBD with three replications, the soil amendments applied on the degraded acidic farmland plots were polyacrylamide (PAM = 40 kg ha−1), biochar (B = 8 t ha−1), lime (L = 4 t ha−1), gypsum (G = 5 t ha−1), PAM+B, PAM+L, PAM+G, and a control. N and P inflows from (atmospheric deposition, biological fixation, and fertilizers), and outflows by (water erosion, leaching, gaseous emissions, and harvested products) were monitored in the 24 plots via NUTrient MONitoring model. Results showed that all of the applied soil amendments improved nutrient balances (by 8–134%) compared with the control. Of the measured outflows, harvested products (43–60%) and water erosion (14–31%) were the major contributors to N depletion, followed by leaching (15–23%) and gaseous emissions (11–13%). Among the applied soil amendments, PAM+L appreciably reduced P loss from water erosion by 61% and N losses from erosion, leaching, and emissions by 55%, 10%, and 3%, respectively, and increased N use efficiency by 31% compared to control plot. Moreover, PAM+L provided a net benefit much higher compared with others. Thus, application of PAM+L would be an effective strategy to combat nutrient depletion and foster crop production in dryland agriculture.