Homemade compost adds nitrogen and other nutrients to soils. It improves tilth and contributes to microbial action that greatly enhances plant health.
No wonder throwing good stuff from the kitchen down the drain or sending organic materials to the dump is anathema to me and to all other organic gardeners. Almost all of it can be used as mulch or turned into wonder-working compost right here in my own home garden. There are a few exceptions to what can be added to a compost pile. Meat, bones, and gravy are no-no’s in suburban settings because they attract wild and domestic animals, but on farms even these wastes are recycled, usually into the tummies of pigs. Pet wastes must never be added to compost, since they contain pathogens that can harm humans, but chicken, sheep, goat, rabbit, cow, or horse manures are fine.
I have always wanted to practice the art of composting here in Southern California, as I did with my family in the faraway places where I grew up. Imagine my distress, therefore, when many years ago I discovered that, for a number of reasons, composting here is not at all easy.
Making compost is a process of piling up organic matter and letting it rot. Originally, compost piles were simply dumps. Farmers and householders threw everything onto an out-of-the way heap, and after a few years, a gardener or farmer could roll up a wheelbarrow and fill it with well-rotted organic matter that he or she dug from the bottom of the pile. This magical material was dark brown or almost black, smelled pleasantly earthy, and had a fine texture. Often it was full of earthworms. By looking at it, one could not discern what had gone into it. The wonder was that all this took no work at all.
In Yorkshire, England, during the 1930s when I was not yet ten years old, I took great pleasure in watching Viney, our head gardener, digging dark brown or black, sweet-smelling, organic matter from the bottom of his compost heap, and then putting it through a sieve in the potting shed and filling pots for planting. He would tuck all manner of flowers and vegetables into the pots and carry flats of them into the greenhouses that were lined up side-by-side on the edge of the large vegetable garden. I stood beside Viney, watching, my nose reaching the level of his potting bench. The experience was sheer bliss. But this kind of life no longer exists, and is like looking back on a dream — another world from what I experience here and now.
Viney’s composting method was the old, original slow method. Sometimes, the pile got hot; other times, it cooled down again. Once in a while it got so hot — most often from grass clippings — that it would burst into flames. A compost pile here that bursts into flames from spontaneous combustion is a badly maintained pile and could be extremely dangerous; it might start a wildfire. But a compost pile that occasionally flamed and then morphed into a slowly smoldering heap didn’t matter much in a climate where the next rain would wet down the pile and leave it smoking. Besides, Viney’s compost pile was sited in an appropriate location, a safe distance from buildings and hidden behind a tall garden wall. The charred remains of twigs and branches simply added some useful potassium to the whole magical concoction. The action of burning had another benefit as it often broke down organic woody stuff too large to rot as rapidly as the rest.
Though the old-fashioned or slow-compost pile was a haphazard thing that took care of itself, the mysterious biological events that took place inside it were the essence of science. The heat that builds up within a compost pile and causes the materials in it to rot is the result of microbial action. By piling up organic materials and keeping them damp, one allows microscopic organisms to eat the organic matter, breaking it down and creating heat and nitrogen in the process. When this material is rotted enough so one doesn’t know what went into it, then it’s time to dig it into the ground, where it becomes what we call humus.
Today’s manufacturers often label bags of compost as “humus,” but this is a misuse of the word. Technically, soil is the thin layer of ground rock and organic matter that covers the surface of our planet Earth, and humus is the partially rotted organic matter that exists in soil. Compost does not become humus until it is added into the soil. Then, as humus, it rots further in the ground and in the process gives off nitrogen into the soil in a form that plant roots can absorb and use for growth. Humus also contains natural fungi that contribute to plant health. Beneficial fungi in homemade compost attack and kill harmful fungi that cause plant diseases. So, making homemade compost does much more than simply adding to the organic content of soil; it is also a fine way to control plant diseases without the use of poisonous sprays that cause cancer, killing us along with whatever else they are meant to attack.
In the 1930s and ’40s, Sir Arthur Howard, J.I. Rodale, and other writers promoted a more complicated and scientific method of composting. Over a period of 30 years in India, Howard had seen large-scale hot composting done in that country. Based on what he saw, he developed a method of hot composting that could be managed by gardeners working on a smaller scale. Howard’s new method produced compost more rapidly than the old method used by Viney and his ilk. Hot composting consists of alternating more or less even layers of nitrogenous materials (wet or green organic materials, such as manure, green leaves, or grass clippings) with carbonaceous materials (dry organic materials, such as wood shavings, dry leaves, chipper materials, raw sawdust, or bagged rabbit litter). First, you create a pile about three feet square — this is the optimum size — by alternating these layers of nitrogenous and carbonaceous materials in roughly even quantities, then you keep the pile damp, and finally you toss and turn it to mix in air. Mixing in air keeps the heat going by providing necessary oxygen, but it also cools down the pile, thus preventing it from getting too hot and bursting into flame as Viney’s pile used to do.