Nitrogen based fertilizers [28%N, 10-34-0, and ammonium sulfate (AMS)] are recommended for use with many herbicides. These products may be used alone or in combination with a surfactant or COC. Nitrogen fertilizers perform different roles than surfactants or COC. One function of nitrogen fertilizers is to prevent deactivation of herbicides by minerals present in water. Sodium and calcium salts may bind to certain herbicides, therefore reducing the amount of herbicide absorbed into the plant. This is the function of AMS with Roundup Ultra. Research has also shown that these compounds may assist herbicide movement across the cell membrane as well as the cuticle.