The plants may be yellow due to lack of oxygen from wet conditions and not lack of fertilizer. Wait for conditions conducive to plant growth before applying fertilizer. See Figure 2 for an application schedule. Fall Assume the growing season begins with the fall rains. Do not apply N if adequate rain does not fall until late October or if the air temperature drops to or below freezing in October.
Many growers apply fertilizer to dry soil and note the disappearance of granules before any rain.
They fear volatile N loss. Nitrogen fertilizers, especially ammonium nitrate, often disappears overnight. Usually, this N dissolves in dew and moves onto the surface soil. In cold conditions, pastures will not grow enough to use fertilizer. Forages in southwest coastal sites generally grow throughout winter, while conditions in the northern Willamette Valley allow only occasional winter growth.