*2.3. Soil Physico-Chemical Properties*

Soil samples were taken from both Alefa and Affesa sites before the intervention of our treatments mainly to observe if there was variability between experimental plots for a paired t-design. Five sampling plots were randomly selected from a total of 10 plots at each site. Considering the maximum root depth of the various crops grown in the study sites (i.e., onion, garlic, potato, cabbage, and maize) in Yimam et al. [22], Iwama [49], and Gao, et al. [50], and the soil layer classification in Westerveld, et al. [51] and Hsu, et al. [52], soil samples were collected from three depths (i.e., 0–30 cm, 30–60 cm, and 60–90 cm). A total of 30 soil samples were collected: 15 samples from each experimental site. Soil laboratory analysis was conducted at Amhara Design and Supervision Works Enterprise (ADSWE) to determine the various physio-chemical properties (i.e., field capacity, permanent wilting point, soil texture, available organic matter, pH, total N, available P, and available K). A representative soil mass of about 1 kg was sampled from each plot. Soil texture was measured using hydrometer, while field capacity and wilting point were determined using pressure (porous) plate apparatus. The details of each laboratory analysis and approach used by ADSWE can be found from Tesema et al. [53]. Coefficient of variation was calculated from the 15 soil samples at each experimental site (i.e., Alefa and Affesa) for each soil physio-chemical properties.
