Changes in land use on soil physicochemical properties: the case of smallholders fruit-based land use systems in arba minch, Southern ethiopia

Fruit-based land use systems and their effects on physicochemical properties of soils were assessed in Abaya-Chamo Basin of Gamo Gofa Zone, Southern Ethiopia. The study area lies between6°30’ to 6°38’ N and 37°33’ to 37°37’ E and altitude of 1200 masl. The physiography is characterized by flat plain under forest and cultivation. A survey was carried out using semi-structured techniques. Land use systems including maize, natural forest, monoculture banana field, and mixed banana and mango fields were identified. Twelve composite soil samples were made from120 random samples collected from the four land-use types. Organic Carbon (OC) and Total Nitrogen (TN) in the surface soils of maize field declined by 61 and 59%, respectively, compared to natural forest during the past 30-40 years. Similarly, OC and TN were reduced by 48.5 and 55.5% in banana and 34 and 52% in mixed fruit cropland fields, respectively, when compared to their contents under natural forest. Likewise, the depletion of CEC in the banana and the maize fields were 32 and 13%, respectively, as compared to the CEC in the forest land. Total nitrogen and Available Phosphorous (AP) contents correlated positively and highly significantly (P< 0.01) with OC and Electrical Conductivity (EC). Generally, OC, TN, PBS, exchangeable K, Ca and Mg, available P, Mn and Fe contents decreased in cultivated land-uses, whereas buildup of OC and TN were obtained in forest lands. The available micronutrients especially Fe and Cu were influenced by the difference in landuse management. These soil properties were positively and highly significantly correlated with TN and OC contents. Therefore, management practices that improve soil quality such as the inclusion of leguminous specious should be employed when converting the land to crop production.