Fig 1.
Locations of study catchment and soil sampling plots: (a) Ethiopia, (b) Aba Gerima land-use/land-cover (LULC) types, and (c) Soil sampling plots.
Fig 2.
Long-term (1994–2021) monthly rainfall (RF), maximum temperature (Tmax), and minimum temperature (Tmin) in the study area.
Fig 3.
Treated with stone-faced soil bunds (a) and with soil bunds (b) at the upper and lower slopes in Aba Gerima catchment.
Fig 4.
Soil spectral measurement: (a) soil samples, (b) FieldSpec Pro spectroradiometer with battery, (c) a close-up of fiber optic cable, and (d) soil reflectance measurement with the sensor.
Table 1.
Descriptive statistics and Shapiro–Wilk probability test of soil parameters in Aba Gerima catchment, Blue Nile basin.
Fig 5.
Pearson’s correlation matrix among soil variables in the 0–30 cm soil layer.
Correlation values are colour-coded. OC, organic carbon; TN, total nitrogen; av. P, available phosphorus; av. K, available potassium. Asterisks indicate significant differences: *P < 0.05 and **P < 0.01.
Table 2.
Analysis of variance in the effect of bunding on soil properties in Aba Gerima.
Fig 6.
Soil reflectance spectra with and without bunding.
Fig 7.
Influence of soil texture on soil spectral signatures.
Fig 8.
Effects of soil organic carbon content on soil spectral reflectance.
Fig 9.
Loading (contribution) of relevant wavelength for modeling soil properties.
(a) Clay, (b) Sand, and (c) organic carbon contents.
Fig 10.
Scatterplots of the model validation results for soil organic carbon (a), clay content (b), and sand content (c). R2, coefficient of determination and RPD, ratio of performance to deviation.