Denitrification (converting nitrate to N gases)
• Leaching (loss below the root zone)
• Erosion and runoff (loss with surface water during rain
events or irrigation)
Since nitrate is susceptible to many transformations and loss
pathways, nitrate concentrations should ideally be no more than
is required to meet plant nutritional needs. Soil nitrate should
be depleted as much as possible by the time harvest occurs to
minimize loss between crops. The use of non-legume winter
cover crops to recover residual soil nitrate can be effective in
some situations.
Soil temperatures in the major crop-growing regions of
California are warm enough to support mineralization of organic
matter throughout the year. This process continues to
contribute soil nitrate all year.