Cotton production in the desert Southwest is commonly characterized by a high input system oriented toward high yields. Water is commonly the first, most limiting factor in desert cotton production systems. Other important inputs include pest control, fertilizer nitrogen (N), and plant growth regulators. Since cotton is very responsive to crop inputs, such as water and fertilizer N, management of these factors is critical to achieve not only maximum agronomic, but also economic yield. Efficient management of all inputs is extremely important for crop management and realizing a profit. Producers need to critically manage crop inputs and have a relatively good assurance that any specific input actually has a high probability of having a positive effect on the crop.