Effects of land use practices on the spatial variability of soil physicochemical properties across a landscape in Wondo Genet, Southcentral Ethiopia

This study investigated the changes in physical, chemical and microbiological soil properties resulting from different land use practices. Soil samples were collected from two different depths, 0-30 cm and 30-60 cm, in three adjacent land use types: agricultural land, plantation forest and natural forest. A total of 15 samples were collected for analysis from each land use type. Key soil parameters, including total nitrogen, soil organic carbon and microbial biomass, were quantified using the micro-Kjeldahl and fumigation-extraction methods, respectively. In addition, geostatistical analysis using kriging interpolation techniques was performed within a GIS framework to visualize the spatial variability of soil parameters. The results showed that agricultural land/khate farm had the highest bulk density (0.96±0.018%), followed by plantation forest/Cupressus (0.93±0.012%) and natural forest (NF) (0.81±0.03%). Natural forest had the highest soil organic carbon content (4.25±0.28%), followed by plantation forest/Podocarpus (2.77±0.49%) and Coffee based agroforestry (2.92±0.16%). Furthermore, the total nitrogen content was highest in the top layer of natural forest (0.37±0.024 μg/g), showing significant differences compared to plantation forest and agricultural land. Microbial biomass carbon was also highest in natural forest (939.84±46.0 μg/g), followed by plantation forest/Grevillea (712.8±48.4 μg/g) and agricultural land/Enset (570.2±38.8 μg/g). Similarly, microbial biomass nitrogen was highest in natural forest (81.0±3.9 μg/g) and showed significant variations with plantation forest/Grevillea (60.08±4.2 μg/g) and agricultural land/Enset (40.96±3.3 μg/g). Overall, our results indicate a strong correlation between microbial biomass and soil physico-chemical properties, which are significantly influenced by vegetation type and soil depth.