Tillage Effects on Soil Moisture and Sulfur use Efficiency by Sesame (Sesamum indicum L.) on Vertisol of North Ethiopia

Sesame, produced in Humera is among the highest quality seeds grown in Ethiopia and even in the world. However, its productivity is by far less than the production potential due to nutrient depletion, moisture stress and lack of crop response to applied fertilizer. An experiment was conducted to evaluate the effects of tillage practices and sulfur fertilizer rates on moisture conservation and agronomic sulfur use efficiency of sesame crop in 2015. The treatments were tied ridges (M1) and flatbed tillage practices combined with five rates of sulfur fertilizer at a split plot design with three replications. M1 and flatbed treatments were assigned to the main plots, while sulfur fertilizer rates were assigned to the sub-plots. Measurements of soil moisture content at 0-20 cm, 20–40 cm and 40–60 cm depth were conducted throughout the growing season at an interval of 13 days using the gravimetric method. The results showed that M1 increased the soil moisture content up to 44% compared to the flatbed. The highest amount of agronomic sulfur use efficiency 14.4 kg kg-1 was also obtained from M1 tillage at 10 kg S ha-1. On the other hand, the highest amount of agronomic sulfur use efficiencies under flatbed tillage was 9.5 kg kg-1 at 10 kg S ha-1. M1 increased agronomic sulfur use efficiency by 51.6%. Tied ridging is the best option to significantly increased soil moisture availability in the root zone and as a consequence it increased agronomic sulfur use efficiency of the sesame. Therefore, in-situ moisture conservation using tillage practices like M1 at farm level should be demonstrated at farmer’s field in the semi-arid Humera areas for improving sulfur fertilizer use efficiency.