Physico-Chemical Characterization of Soils for Fertilizer Recommendations for Some Districts in Bench-Maji Zone, South West, Ethiopia

Understanding the characteristics of soils is prerequisite for designing appropriate management strategies towards natural resource management for sustainable development. The study was therefore carried out at four districts in Bench-Maji Zone with the objectives of determining soil physical and chemical characteristics for determining the recommended rate of N and P fertilizer. The representative soil profiles for each site were opened. A total of 16 surface and profile soil samples were collected for characterization of selected physicochemical properties of soils. The soil characteristics employed during characterization and classification were soil texture, bulk density, porosity, soil color, consistence, pH, organic carbon, total nitrogen, organic matter, C:N, available phosphorus, exchangeable bases, CEC, ECEC, PBS, ESP, EC and available micronutrients. The soil morphological and chemical properties were characterized and the recommended rates of N and P fertilizers for the districts were determined using NuMaSS (version 2.2) software. The NuMaSS nutrient diagnosis result showed that, high probabilities of P and N deficiencies were observed in almost all districts. It can thus be generalized that the soils of the districts have serious nutrient limitations. The prediction of fertilizer requirement by NuMaSS showed, recommended amount of P for maize crop ranged from 0 kg P/ha to 67 kg P/ha. Highest dose of P (67 kg P/ha) was required for soil of North-Bench followed by 52 kg P/ha for soils of Gurafarda, 47 kg P/ha for Soils of Debub-bench and no P required for soil of Jemu. The recommended amount of N for soils of Gurafarda, Debub-Bench, North-Bench and Jemu were 0 kg N/ha, 98 kg N/ha, 68 kg N/ha and 69 kg N/ha respectively. In addition, soil of Gurafarda, Debub-Bench, Jemu had no exchangeable Ca2+, Mg2+ and K+ problems. However, the soil of North-Bench had low Ca2+, medium Mg2+ and deficient to marginal K+ contents. Besides to nutrient recommendation, other management activity for the amelioration of these acidic soils is advisable. In general, management activities for these soils; should be practiced, and the strategies for which should be determined according to the crops being grown.