EFFECTS OF BORON FERTILIZER RATES ON SELECTED SOIL PROPERTIES, GROWTH AND GROWTH PARAMETERS OF SORGHUM (SORGHUM BICOLOR L.) IN HARAMAYA DISTRICT, EASTERN HARARGHE ZONE, EASTERN ETHIOPIA

Currently, more attention is being given to fertilizing the soil with micronutrients in many Sub-Saharan African countries including Ethiopia. This study was initiated to assess effects of boron fertilizer rates on selected soil properties, growth and growth parameters of sorghum (Sorghum bicolor L.) in Haramaya District, Eastern Hararghe Zone, Eastern Ethiopia. A preliminary survey and field observation were carried out to get general information about the landform, vegetation cover and land uses, whereby 4 peasant association were selected from potential sorghum producing areas. A total of 64 soil samples from the topsoil (0-20 cm were collected from 4 peasant associations. A pot experiment was conducted in randomized complete design (RCD) with three replications and five levels of Boron concentrations ((0 (control), 2.8, 7. 9.8, 11.2, and 14, kg/ha ) in pots of 70 cm diameter and 50-cm height containing soil from the study area at Haramaya University in Greenhouse, Rare site. The study revealed that the initial average boron content of the soil of the study area ranged from 0.143 to 0.743 ppm, which is in the low range and the pH of the soil was 6.21. There was a significant improvement in available boron in the soil after the crop harvest (3.23 ppm) as compared to initial content (0.143 ppm) at 1.4 kg/ha. The maximum organic carbon in soil (1.27) was recorded at the treatment fertilized with 0.98 kg/ha. The maximum Available phosphorus (14.6 ppm) was recorded at treatment three. The boron contents in the shoot tissue increased significantly (p ≤ 0.05) with increased concentrations of Boron from 0.05 ppm at 0 mg kg -1 to 1.91 ppm at 14 kg/ha. Plant height was significantly higher (69.33 cm) at (P ≤ 0.05) at 9.8 kg/ha than the plant height at control (52.56 cm) and 14 kg/ha (52.5 cm). The highest mean value of green matter was recorded (70 g) at 9.8 kg/ha. The amount of boron used was found to increase significantly with the increased concentrations of Boron from 0.05 ppm at 0 kg/ha to 1.71 ppm at 14 kg/ha (P ≤ 0.05). Boron addition of mg 9.8 kg/ha seems to be the optimum rate for plant growth. Since this study was conducted under greenhouse conditions further study should be conducted under field conditions to recommend appropriate doses.