For farmers and researchers, a field is often like a giant chemistry set. The timing and amounts of different fertilizers to supply nutrients can interact with each other, the soil and crops. For example, potassium, an essential macronutrient for crops, is often applied to a field in the form of potassium chloride. Potassium and nitrogen are the two nutrients that crops need in abundance. Past research has documented an uptake between chloride and nitrate, a form of nitrogen that crops take up.