Abstract:
A study was conducted in Dodoma district, Dodoma region Tanzania to assess the soil fertility status for sesame production. The study was initiated due to the continuous decline of sesame yield to alarmingly low levels. The objectives of the study were to determine the levels of N, P, K, S, Mg, Ca, Na, Zn, Cu, Fe and Mn in soils and evaluate the response of sesame crop to the application of N, P, K, S and Zn. This was done by analysing soils from twenty sesame growing areas of Dodoma district. The analysis included determination of total N, OC, P, exchangeable bases and micronutrients, and then field experiments were conducted at two sites located at Makutupora and Hombolo villages. The plant samples were analysed for N, P, K, S, Ca, and Zn. The results of soil analysis indicated that all the soils analysed were deficient in N, about 70% had low available P, 90% had low extractable S and 60% had low Ca levels. Also, most of these soils had low Zn levels and only one site had adequate Zn levels. All the soils had adequate levels of Mg, K, Cu, Fe and Mn. The field experiment showed that application of N, P, K, S and Zn increased nutrient contents in sesame at both sites. However, the deficiency was observed in the absolute control treatments. It was further revealed that combined application of sulphur along with Zn and N, P and K significantly increased seed yield and straw dry yield. Following the results from the field exeriments, it was concluded that most of the soils under sesame production in Dodoma district that were analysed through this study were deficient in N, P, S and Zn. However, in order to optimise production and increase sesame yield, these nutrients (N, P, S and Zn) must be applied at rates of 45 kg/ha, 20 kg/ha, 45 kg/ha and 25 kg/ha, respectively.
