Germination damage is also controlled by the fertilizer form. Fertilizer Form Fertilizers can damage the seed in two ways. The first, and most serious, way that fertilizers damage the seed is by specific toxicity. The second way is by salt damage. All commercial fertilizers dissolve in water and make the soil solution saltier near the point of application.
Most phosphate fertilizers have a minimal salt effect.
Fertilizer form controls the amount of nitrogen that is released into the soil as NH 3 . The NH 3 causes severe injury when in close proximity to the seed. The greatest potential for germination damage occurs with anhydrous ammonia because it is released into the soil as NH 3 . Urea fertilizer has the next highest potential to lower seed germination. Although urea is not an ammonium fertilizer when applied in the granular form, it quickly hydrolyzes to ammonium carbonate in the presence of the urease enzyme commonly found in soil.