Uncomposted Mulch Not a Big Concern

 Q. Does incompletely composted material draw fertilizer components away from plants?

This is mulch. It should be applied to the soil surface.  "Mulchy" compost will have alot of wood undigested wood fibers in the finished product. You can see it. A product with  too much undigested mulch should not be used as a compost.

A. The finer the compost, the faster it will decompose. I don’t like compost that looks “mulchy” because that mulch appearance can mean it is not totally broken down. Mulchy compost will present a problem when preparing the soil, both with too many air pockets and the possible production of methane gas.

Viragrow Compost is totally decomposed so you cannot see any of the ingredients anymore. Any large pieces of green waste such as wood chips was screened out of the finished product. This helps to prevent air pockets and methane gas.

      Compost for vegetable gardens should be screened, be dark brown or black, smell good and earthy. Composts like this are good for preparing the soil for the planting of trees and shrubs. These composts are finished and will no longer break down. At this point the compost is called "humus".

      If compost is not completely broken down it can draw nitrogen out of the soil and possibly become a problem. When compost is nearing completion it should be consistent in color. But it depends on the carbon to nitrogen ratio of the compost. Even worse than that, if it continues to break down for a long time, deep in the soil, it will become anaerobic and produce methane - very toxic to plants and will cause plant death.

This wood surface mulch was applied to this desert soil. As long as it becomes wet it will slowly decompose using nitrogen to fuel the microorganisms and add nutrients to the soil, organic matter and enrich it. But mulch should never be buried or it can produce methane gas, a powerful plant killer and greenhouse gas.

Usually in regularly fertilized garden beds I do not worry about robbing nitrogen from the soil if the compost is not totally totally broken down.  Manure mixed into the soil is used all the time for vegetable production in many countries. But I do lightly fertilize vegetables once a month and this additional nitrogen keeps this kind of problem at bay. I use undigested compost as a surface mulch rather than burying it.