In June, Suzette Striegel from the Mahaska County Extension Office presented a program on composting to the Centerville Garden Club. The reference materials used for this article are available though Iowa State Extension. Ms. Striegel shared the following about good composting practices.
Compost is an organic amendment to improve soil. Adding compost to garden soil improves the soil’s ability to hold water and increases productivity. Soil with compost will act as a sponge soaking up water when it rains and slowly releasing water during dry spells. Compost improves the structure of both sandy and clay soils. A couple of different techniques for composting are active composting or passive composting. Active composting involves adding ingredients, maintaining temperatures, turning (weekly), maintaining moisture and harvesting. Passive composting only involves harvesting and is used primarily when there isn’t a lot of direct hot sunlight. To start, first select a location, preferably away from the house with access to water. Next choose a style, either one bin, two or three bins or bin-less. There are good directions for building your own bins from ISU extention.
A rule of thumb is anything that has lived can be used in your compost. Most yard and garden waste can be used for composting, such as; leaves, grass clippings, straw and finely chopped tree and shrub trimmings. Some kitchen scraps can be added to your compost including fruit and vegetable waste, coffee grounds and egg shells. Bury food scraps in the pile to help prevent odors and flies. Do not add meat scraps, bones, grease, whole eggs or dairy products. These items break down slowly, will smell badly and can attract rodents. Ingredient size matters. Smaller pieces of plant material is better.
One of the most important factors for composting is maintaining a balance of carbon and nitrogen. A ratio for C:N is 30 parts carbon to one part nitrogen. Carbons are brown ingredients; dry leaves and yard waste, dried grass clippings, shedded newspapers, saw dust and wood chips. Nitrogens are green materials; fresh grass clippings, fruit and vegetable waste, egg shells and coffee grounds. Layer loosely alternating browns with some greens. Monitor your compost pile. Turning weekly adds oxygen. The pile should feel warm and moist. Examples of problems are an ammonia odor meaning too much nitrogen. Add browns. A rotten egg odor means oxygen is needed, so turn the pile and add dry ingredients. Add dry material if there is too much water.
A good compost pile which has a mixture of chopped material, is turned regularly and kept moist will be ready to use on your garden in about two to four months. You will know when your compost pile is ready to use because it will be half its original size and will have a nice earthy smell.