Organic Nitrogen Sources.

One of my favorite topics has been nitrogen management.  I recently had a discussion with some people about the value of organic nitrogen sources in pollution prevention.  Some of them did not realize that organic sources of nitrogen can cause nitrogen pollution just as commercial fertilizers can.  Organic producers often look to manure or legumes (AKA green manure)  as a nitrogen source.  A strong argument can be made for using such sources to reduce the need for commercial fertilizers in conventionally grown cropping systems as well.  Keep in mind that organic sources of nitrogen go through the same nitrogen cycle as commercial fertilizers.  Organic nitrogen it too complex for plant uptake and must be broken down to nitrate and ammonium forms of nitrogen.  The ammonium for is further broken down to nitrate which is the preferred source of nitrogen for most plants.  Once the nitrification (transformation to nitrate) occurs the nitrogen is just as subject to loss from leaching or denitrification as commercial fertilizers are.  The good news is that organic nitrogen is slower release.  The bad news is that organic nitrogen is not foolproof.  Over application is still possible.  Also be sure to take credit for organic nitrogen when you are using legumes and manure along with commercial nitrogen.