Abstract:
Depletion of soil fertility due to soil erosion and nutrient mining farming system leads to decline in soil productivity and subsequently crop yields. This study was initiated to assess soil fertility status and to determine micronutrient concentration in the tissues of maize and sorghum grown at Daro Labu district, Eastern Ethiopia. Twelve maize and twelve sorghum growing fields from four peasant associations (PA) were selected purposively. Field survey was conducted to collect general information about soil fertility management practices and record spatial data. A total of 24 composite soil samples from the depth of 0-20 cm and 12 maize and 12 sorghum tissue samples at appropriate stage were collected from selected PA during the main cropping season of 2018. Data were analyzed by using SPSS version 20. The soil texture was sandy clay loam and sandy loam for soil of maize and sorghum fields respectively. Soil bulk density of maize (1.33 - 1.42 g cm-3) and sorghum (1.35 - 1.53 g cm-3) fields were within an acceptable range. The total porosity for soil of maize (41.49 - 45.27%) and sorghum (41.49 - 45.27%) fields were very high. The soil pH of maize (6.33 - 6.77) and sorghum (6.31 - 6.93) fields varied from slightly acidic to neutral level. The soils were very low to low in OM content with values ranging from (0.87 - 1.47%) and (0.60 - 1.18%) for soil of maize and sorghum fields respectively. The TN content of soil for maize (0.04 - 0.22%) and sorghum (0.06 - 0.14%) growing fields was low. The soils were better in their available P content with the values ranging from 10.08 - 16.20 and 8.43 - 12.07 mg kg-1 for maize and sorghum fields respectively. The CEC of soil ranged from medium to high. Exchangeable Ca and Mg were found to be high and medium respectively while, that of Na was Low to medium in soils of the study area. Exchangeable K was high to very high for soil of maize whereas, low to medium for soil of sorghum fields. The soil had adequate level of DTPA extractable Fe and Mn whereas deficiency of Cu and B was recorded in 100% of soil. The soil of maize and sorghum fields showed deficiency of Zn in 25% and 75% of soil respectively. Maize tissue had sufficient concentration of Fe (57.40 - 86.00 mg kg-1) and Mn (40.30 - 65.67 mg kg-1) and also sorghum tissue had adequate concentration Fe (62.40 - 116.80 mg kg-1) and Mn (23.88 - 38.81 mg kg-1). However, 41.67%, 41.67% and 75% of maize tissues were deficient which varied from Cu (1.75 - 14.04 mg kg-1), Zn (15.69 - 25.10 mg kg-1) and B (0.36 - 6.68 mg kg-1) concentration respectively, and also 66.67%, 16.67% and 58.33% of sorghum tissues were deficient with a range of Cu (0.35 - 10.53 mg kg-1), Zn (7.06 - 20.39 mg kg-1) and B (0.18 - 4.69 mg kg-1) concentration respectively. The extractable Fe, Mn, Cu, Zn and B concentration in a plant tissue were positively correlated with their respective soil micronutrients. The physical parameter studied indicate that the soils are at normal condition, while chemical fertility parameters such as OM, total N, K, Cu, Zn and B are the limiting factors for crop production. The use of sustainable soil nutrient management practices with increasing organic matter addition should be implemented. Fertilizers containing Cu, Zn and B need to be applied by conducting further experiments under green house and field conditions by considering soil type and crop variety for realizing better production in the study area. The rating of soil and plant nutrient content should be done by considering the local situation.