When properly applied, they also reduce the chance of foliar burning that is common with ammonium nitrate and urea. Foliar burning is the brownish discoloration that occurs on grass blades as a result of contact with soluble fertilizer. It can be minimized by watering the lawn immediately after fertilizing. Slow-release sources are less susceptible to leaching and are preferred on sandy soil types, which tend to leach. If WIN is not listed on the fertilizer label, youshould assume that it is all water-soluble or quickly available nitrogen.
Urea nitrogen is a water-soluble source of nitrogen.
Most fertilizers are applied at a rate determined by the type and amount of nitrogen present in the material. Nitrogen is the nutrient most used by the grass and often is the material that burns the lawn if applied at excessive rates. The pounds of actual N in every fertilizer can be determined by dividing the percent N listed on the label into 100. The calculation is the same as the first example. Excessive spring application of nitrogen to cool-season turfgrasses is detrimental because it leads to excessive leaf growth at the expense of stored food reserves and root growth.