Potassium is an essential macronutrient for plants, and its availability strongly affects biomass production, tolerance to stress, and yield. Since only a small fraction of the soil potassium content is plant available, plants must develop efficient strategies for the uptake of potassium from the soil. The most important strategy used by plants to acquire nutrients is the arbuscular mycorrhizal (AM) symbiosis, a mutualistic association between the majority of land plants and ubiquitous soil fungi. AM fungi play an important role for plant and soil health. These beneficial fungi take up nutrients and water from the soil and deliver them to the plant. Although most studies have been done on the acquisition of phosphorus and nitrogen, we have recently demonstrated that AM fungi also have a positive impact on the potassium nutrition in legumes. A better understanding of the strategies used by legumes, and particularly soybean, to acquire potassium will be crucial to improving future crop productivity and environmental sustainability of crop production. The increasing demand for food and the development of alternative strategies for enhancing crop yields while reducing the use of chemical fertilizers represents a critical priority. We propose here to test if similar benefits provided by AM fungi can be observed in soybean in the field and in greenhouse, and to quantify the actual transport of K from the soil to mycorrhizal soybean roots in laboratory condition. The proposed project will allow us to determine whether AM fungi affect the yield, nutrient content, and productivity of soybean under different K regimes. Disseminating these results within the North Carolina Soybean Producers Association will help local soybean growers and producers to breed and select varieties that are able to interact more efficiently with mycorrhizal fungi, and to reduce the use of potash without affecting soybean growth and yield.