One of the main concerns with these and other forages is the accumulation of nitrates, which can lead to nitrate toxicity.

The yield and quality of most summer annual forages is increased significantly with nitrogen fertilization, even on dry years. So, how much fertilizer, if any, should be applied to a forage crop.

The primary cause of nitrate accumulation in a forage plant is weather that limits photosynthesis and growth, which in turn slows or prevents the conversion of nitrate to protein. This normally indicates drought conditions, but can be caused by a period of cool, cloudy weather.

Nitrate levels in the plant go up rapidly when severe drought stress is first broken by a rain shower. Nitrate uptake can be very rapid as growth first takes off, and can stay high for several days until photosynthesis catches up to the growth.