This paper discusses methods of combining fertilizers and pesticides for simultaneous application. The following are two reasons for the growing interest in producing and applying fertilizer-pesticide mixtures:

1. It saves time, energy, and money by reducing the number of separate application operations.

2. The scarcity of farm labor and the need for accurate and uniform application, especially of pesticides, cause farmers to use custom application rather than buy and maintain increasingly expensive application equipment.

Since only a small quantity of active pesticide is usually recommended, compared with several hundred times this amount for fertilizers per hectare, dry fertilizers are usually coated with either powdered or fluid pesticides, to provide adequate ground coverage, rather than mixed with granular pesticides. The powders must be stuck to the fertilizer to prevent segregation and dusty, nonuniform application. Fluids used for sticking agents may be the pesticide or pesticide carrier. This fluid should not overwet the fertilizer since this will cause a sticky or nonapplicable mixture.

With fluid fertilizers it is necessary to make sure that the fertilizer and pesticide are physically compatible. A four-step procedure for testing physical compatibility is outlined. Whether applied separately or in a fertilizer-pesticide mixture, pesticides should always be used according to the instructions on the pesticide label.