Subject: [NAFEX] Re: What is inadequacy in typical compost?
Date: Tue, 15 Mar 2005 06:08:23 +0000 (UTC)
Charlie,
In preparing compost, people generally aim for a 20:1 carbon to nitrogen
ratio to supply N to crops, and if you've got vegetable scraps in it
you've probably got lots of other elements too (K, P, Ca, trace nutrients,
etc.) Hardwood leaves can have high C:N ratio, e.g. 40:1 which will tie
up N as the microbes use the abundant C and scavenge all the N, making the
N unavailable to plants. Food scraps and manures tend to be on the low
side, say 15:1, which means the N either mineralizes or is lost as N2 gas,
but the N is plant-available and so the compost functions more like a
fertilizer. The below webpage introduces the C:N balancing concept and
gives a list of C:N ratios for common mulch and compost materials at
the bottom.