The effect of cropland fallowing on soil nutrient restoration in the Bale Mountains, Ethiopia

Abstract

Fallowing is considered an important management practice in maintaining soil productivity. This study investigated the level to which traditional cropland fallowing restored soil fertility in the Bale Mountains of Ethiopia. It included a comparison among a three-year fallow, cropland and natural forest. A total of 36 surface soil samples (3 altitudinal ranges×3 landuse types×4 soil samples from 0–0.20 m depth) were collected and analysed for soil organic carbon, total nitrogen, exchangeable bases, cation exchange capacity (CEC) and percentage base saturation (PBS). Results showed that soil organic carbon content (p<0.001) and total N (p=0.001) were significantly higher in the fallow land and natural forest than in cropland. Except for exchangeable Mg2+ and Ca2+, the differences in exchangeable bases were significant with landuse types. Exchangeable K+ was higher in the fallow land than in cropland soils. Cation exchange capacity and PBS also showed significant variation with landuse type (p<0.001 and p=0.004, respectively) and altitudinal ranges (p<0.001 and p=0.006, respectively). The overall mean CEC was higher in the natural forest and fallow land than in cropland. The CEC in fallow land was strongly related to the soil organic carbon (r2 = 0.84, p<0.001). The nutrient build-up and rise in CEC and PBS in soil within the three-year fallow period could be due to the addition of soil organic matter.