Variation in soil properties under different land use types managed by smallholder farmers in central Ethiopia

Land use change causes a remarkable change in soil properties. The nature of change depends on multiple factors such as soil type, type and intensity of land use, climate, and the like. It is essential to study and understand how these factors interact and affect soil properties. In this study, we investigated the variation in soil physicochemical properties across five common land use practices, i.e. enset system, farmland, and grazing-land (closed and open), and Eucalyptus woodlots practiced on originally same soil type and comparable topographic and climatic settings. A total of 105 soil samples from three depths of 0-15 cm, 15-30 cm, and 30-45 cm were collected and analyzed for selected soil physicochemical properties. The results showed significant differences between the land uses in soil physical and chemical properties. Enset system had higher pH, available phosphorus (P), exchangeable potassium (K+), soil organic carbon (SOC), and total nitrogen (TN) and their stocks than other land use types. Further, the widely accepted notion of the alleged effects of Eucalyptus tree on soil nutrient composition was not demonstrated in this study except its lower pH of (5.61) and soil moisture contents of (26.14%) than other land use types over 15-20 years old. SOC stocks showed a decreasing trend of enset system (127.36 Mg ha(-1)) > closed grazing land (108.07 Mg ha(-1)) > eucalyptus woodlot (92.55 Mg ha(-1)) > open grazing-land (88.57 Mg ha(-1)) > cereal farm (76.65 Mg ha(-1)) at 0-45 cm soil depth, implying the potential of enset system for climate changes mitigation. TN was also measured in the same trend. Overall, some land use systems (e. g. enset agroforestry) improve the soil biophysical and chemical properties, while others such as cereal production degrade the soil. The low input continuous cultivation of cereal farm land coupled with its poor soil conservation measures in the area could be the major factors for the depletion of soil nutrient in cereal farming. Hence, future soil management strategies should be focused on mitigating the continuous loss of soil nutrients from the dominantly practiced cereal cropping system through the retention of crop residues, practice of crop rotation and scaling-up agro-forestry practice.

Automated summary

Land use change has a significant impact on soil properties. This study investigated the variation in soil physicochemical properties across different land use practices and found significant differences between them. Some land use systems, such as enset agroforestry, improve soil properties while others, like cereal production, degrade soil. Therefore, implementing appropriate soil management strategies is crucial to mitigate soil nutrient loss.