The amount of water and fertilizer in the soil affects how much soybeans can grow on sloped land. Adding more water makes soybeans grow better, and using the right amount of phosphorus and nitrogen fertilizers also helps. When used together, these fertilizers increase soybean yield and water use efficiency more than when used alone. The best ratio of nitrogen to phosphorus is 1.3 to 1. Overall, adding fertilizer can boost soybean yield by up to 470% and water use efficiency by up to 438%.