Stella Otto: The Backyard Fruit Gardener

Today's Tip: Mow vegetation short around the base of fruit trees and bushes to reduce winter habitat for rodents.

Factors that Affect the Composting Process

Finished compost ready for the fruit garden

Fin­ished com­post ready for the fruit garden

Given even remotely accept­able mate­ri­als and con­di­tions, com­post will occur over time. The break­down of organic mat­ter is a nor­mal part of nature’s cycle. To cre­ate com­post in a timely man­ner and of qual­ity that is use­ful in our gar­dens, it helps to under­stand how some fac­tors influ­ence the com­post­ing process.

Car­bon and Nitro­gen sup­ply­ing mate­rial — These mate­ri­als are the food and energy sources for the microor­gan­isms that facil­i­tate the com­post process. They will also pro­vide numer­ous nutri­ents to feed our plants once bro­ken down into their chem­i­cal components.

Air — Com­post­ing is an aer­o­bic process; that is one that takes place in the pres­ence of oxy­gen. Lack­ing oxy­gen, the process will become anaer­o­bic. The pile will fer­ment and may start to smell.  The com­post pile needs to con­tain some pore space to allow for the pres­ence of air. Mix­ing small par­ti­cles with larger coarse par­ti­cles will cre­ate needed pore spaces. Turn­ing the pile as bro­ken down mate­r­ial starts to set­tle and the process slows down, also fluffs up the pile and intro­duces air to keep the oxi­da­tion process moving.

Mois­ture — This is pos­si­bly the most impor­tant fac­tor influ­enc­ing the com­post­ing process. Ide­ally, you want to main­tain a mois­ture con­tent between 40 and 60% — that is moist, but not drip­ping — much like a wrung out sponge. If you can squeeze mois­ture from your com­post it is too wet. In wet areas or rainy sea­sons, cov­er­ing the com­post pile may be needed. Like­wise, in the heat of a dry sum­mer, you may need to water your pile; just as you would your gar­den, if there is not enough nat­ural rainfall.

Tem­per­a­ture — The com­post process typ­i­cally takes place best between 120 and 150 degrees F. This is the tem­per­a­ture range within which the microbes involved in the process func­tion best and repro­duce to keep the process mov­ing. If weeds with seed heads are thrown on the pile, as is often the case, the seeds will lay dor­mant to sprout later in your gar­den unless the pile becomes suf­fi­ciently hot to kill the seeds. This is typ­i­cally achieved at 130 degrees F or above. Com­post piles smaller than a cubic yard may not heat up suf­fi­ciently to kill weed seeds.

Par­ti­cle size — Smaller par­ti­cles have more sur­face area exposed for microor­gan­isms to pop­u­late. Con­se­quently, smaller par­ti­cles will be bro­ken down more quickly to a use­ful com­post. When adding coarse mate­ri­als to the pile such as woody branches, corn cobs, or tough plant stalks, it is help­ful to chip, grind, or cut up these mate­ri­als for faster composting.

Pile size or vol­ume — Small vol­ume com­post piles have a ten­dency to dry out too quickly and require more fre­quent water­ing. In north­ern cli­mates the win­ter tem­per­a­tures may be too cold to allow com­post­ing to occur on the exte­rior of the pile. If the pile vol­ume is large enough, as sug­gested ear­lier, the inte­rior of the pile will con­tinue to “work,” albeit at a slower pace.

For more infor­ma­tion see —

Cre­at­ing Com­post
Com­post — Where to Begin
Con­tain­ing Your Com­post
Recipe for a Com­post Pile
Com­post No-nos: What not to put in your com­post pile

Stay tuned for  —

Com­post Conun­drums — Trou­bleshoot­ing your com­post pile
Com­post Myths