Composting, by definition, converts raw organic materials into humus, a vital soil additive. Composting garden and kitchen scraps allows you, the gardener, to establish your own recycling, sustainable ecosystem.
Garden compost is a mixture of vegetable waste materials (eg: coffee grounds, crushed egg shells, apple cores) which are collected together in an enclosed container and left to rot. Properly made and well rotted, garden compost can take the place of animal manures. Organic matter is a necessary addition to garden soil. It provides plants with nutrients and acts to aerate the soil structure, while fertilizers provide food but no humus. Rotted organic matter provides humus, which is vital for vegetable development.
There are five necessary conditions in making a good compost: oxygen, moisture, warmth—inside and outside, and nitrogen and a proper carbon-to-nitrogen ratio. All conditions help bacteria live and function successfully to break down organic matter into humus. The heat generated by the composting materials, kills pathogens and weeds, and keeps the bacteria happy.
Any soft vegetable material can be added to the compost heap: grass clippings—making up the bulk of the heap, flowers, leaves, stems. Vegetable waste can also be put into the heap—potato peelings, fruit skins, lettuce stubs, ect. Tough woody stems and evergreen leaves do not rot quickly and should not be added to the heap. Also, you should keep the compost heap free of plastic, glass, and stones, in addition to pest-ridden or diseased plants. Invasive weeds and seeds should be burned along with rhizomes. Any animal by-products should be kept away from the compost heap, since raccoons and rats are attracted to such waste. The heap should contain approximately twice as much brown matter as green matter, by volume. Brown matter is high in carbon—leaves, hay, sawdust, straw, woody prunings. Green matter is high in nitrogen, consisting of soft vegetable materials. Smaller pieces the better, since they decompose faster.
A 3 X 3 X 3’ compost heap will yield approximately half a ton of compost. The faster the heap is constructed, the faster the temperature will rise, accelerating the rotting process. Wooden slats, brick, wooden poles, wire mesh all work well as construction material for a compost heap. A square container of 2” wire netting supported with wooden posts (make sure the wood used is decay resistant: heartwood or redwood) can be constructed quickly.
The compost heap is built directly in the soil, with a base of woody stems of 1” deep. Build layers 4-8” deep of vegetative material (green matter) followed by 1” of soil with some lime sprinkled on top, to keep the acidity high, closer to a neutral pH, and then a layer of brown matter. Repeat layers until desirable height is reached. Keep air pockets to a minimum. Spray each layer lightly with water. In turning your compost, the sides should be moved to the middle, which will keep rotting consistent throughout the entire heap and help dispel any unpleasant odors from arising. It should be turned weekly, to accelerate decomposition by introducing more oxygen to the pile. If necessary, add more water, so the pile is slightly moist.
When your compost is ready to use it should be dark in color and be crumbly, resembling fibrous soil. If you can still identify what you placed in the heap, then the compost is not yet decomposed enough to be considered organic material, and should be given more time. 10 pounds per square yards should be used in poor, sandy soil, or in soil that is short in humus and stony. In better soils, you need only to use about half the amount (5 lbs per square yard). Organic matter should be added in autumn when preparing planting beds for spring growing, or about a month before tree or soft fruit plantings.
(Sources: Sunset Western Garden Book, and Home Growing—by Edwin F. Steffek)
