Crop production has increased dramatically over the last few decades, much of which has been due to the widespread introduction of chemical fertilizers starting in the mid-1900s. Matching fertilizer application rates to crop needs is an essential component of optimizing crop production. However, different crops in separate fields will require varying rates of the major nutrients – nitrogen (N), phosphate (P2O5), and potassium (potash, K2O) – due to variations in soil types, soil test phosphorus and potassium levels, and nutrient ranges of different crops.