Abstract

Soybean (Glycine max L) is among the most important legume crops produced in Ethiopia. However, declining soil fertility and poor soil fertility management practices decrease yields. Nitrogen fertilization is necessary to improve yield and quality of soybean at certain application times or rates. In order to achieve high yield potential, soybean must maintain high photosynthesis rates and store large amounts of N in seeds Sulfur (S) is among the 17 essential nutrients for healthy plant growth and is a requirement for soybean. With N, phosphorus, and potassium being primary macronutrients, S is a secondary macronutrient. In order to achieve maximum plant growth and high yield, nutrients must be at adequate levels. Phosphorus along with nitrogen and potassium is a primary nutrient required by plants to complete their life cycle. It's especially important during the early stages of growth and development. One important role of P in plants is to store and transfer energy produced by photosynthesis which is then used for growth and reproduction. If P is limiting, plants cannot grow adequately, which limits their ability to cope with stress. Slow root and shoot development results in delayed maturity and reduced yields although soybean yields have increased over the past decade, even greater improvement is in demand. Nontraditional practices such as applying nitrogen (N) to soybean for yield optimization might be one way to meet this demand. Also, sulfur (S) is becoming a more important limiting nutrient in production due to higher yielding crops.