[USCC] Availability of N from compost

[Steve Diver]

Hello Eugene -

It's good to see practical questions for end use of compost
on USCC. 

The information you've provided is helpful, but it would also
be good to know the application rate in tons per acre and
when crops will be established.

Your other post indicates that you're not sure about the
quality of compost.

If you sat down with an agronomist and looked over compost
and soil test analysis along with the crop schedule, it would be
much easier to grasp the situation.

I'd like to see light incorporation of the compost, especially
with crop residues, perhaps using an Aerway type implement. 

Nitrogen release will happen as soil temperatures, crop roots, and
rhizosphere / compost biology work together.    The biggest fertility
impact from compost is microbial-driven, beyond NPK analysis. 
The C:N ratio of compost is a good indicator of nutrient release.

March-applied compost should provide nutrients for late
April or early May planted crops. 

But the cropping situation depends on your cover crop,
compost quality, and rate of compost application.

Organic farms ideally build organic matter that provides
reserve fertilty each year.

What does Iowa State Univ or Practical Farmers of Iowa
suggest?

Best regards,

Steve Diver
NCAT-ATTRA


Eugene R. Moore wrote:

>Approximately how many days after spreading would one expect the N in a 
>compost to become available to a plant, if spread during the spring?
>
>More specifically, assume the following:
>
>Compost is broadcast spread, without any incorporation, during mid to late 
>March---------In southern Iowa.
>Thawing would have started by then, but soil temperatures would not reach 50 
>degrees F until about late April.
>First year available N is 12lbs according to lab tests.
>Weather conditions are as they have been for the last several 
>years--------lots of rain in early May.
>
>What would be the probable time table for the first year N to become 
>available to the plant?.........late May?    Mid June???
>
>  
>