One of the variables in any fertilizing program is measuring the amount of nitrogen is available to the plants over time.  Most vegetables will be happy with having 2 to 3 pounds of nitrogen per 1000 square feet over the growing season. [Note – turfgrass needs 4 lbs. of N per 1000 square feet]  Generally 3 applications of quick-acting nitrogen fertilizer or one application of slow release nitrogen fertilizer provides 3 to 4 pounds of N per 1000 square feet.  

 

However, those of us who pay attention to our soil and make sure there is an addition of organic matter to our soil every year, have something else going on down below the soil’s surface.  Earthworms are coming to the surface and grabbing a piece of organic matter and pulling down into the soil.  The earthworms eat some of their harvest but also spread uneaten particles around for other creatures to chomp on.  Soil with only 5 earthworms per cubic foot will get 1 lb. of N from those worms each year.  Most gardens having had organic matter added yearly have 10 to 15 worms per cubic feet; that is 3 lbs of N per year from earthworm poop alone.

 

Nitrifying bacteria will produce about the same amount of N each year as do the earthworms.  Other microbes contribute more for a total of 2 to 3 more pounds of N per 1000 square feet.  Why are you using any fertilizer?