Composting Yard Waste: Making Compost

To make traditional compost, alternate different types of shredded plant materials in 6- to 8-inch layers. Layering helps compost reach the correct nitrogen balance. Use equal parts by volume of dry and green plant materials in the overall mix. Use caution when you add layers of fine green plant wastes such as grass clippings. Grass mats easily and prevents water from moving through the mass. Use 2-inch layers of fine materials or process them through a machine shredder. Alternate fine materials with woody plant prunings to prevent clogging the machine and to create an equal balance of dry and green materials.

Traditional composting includes soil as one of the layers. While soil can serve as a source of microbes to “inoculate” plant wastes, research has found that the microorganisms that break down plants also are present on the surface of the leaves and stems. It’s natural for some soil to cling to pulled weeds and uprooted vegetable and flower plants. When you add large amounts of soil, you increase the weight, which makes composting difficult and less efficient. Large amounts of soil also can suffocate microorganisms. Soilless composting is often practiced.

Add water to the compost after every few layers of material. If the plant materials are dry and no green material is available, add a small quantity of blood meal or a commercial nitrogen fertilizer free of weed killers. One-half cup of ammonium sulfate per bushel of material is sufficient. Livestock manure also can be added and supplies some nitrogen. Like soil, manure adds weight and bulk. The space devoted to manure could be used to compost yard wastes.

There is no advantage in adding compost starters or inoculum to the compost. The microbes that cause decomposition multiply just as rapidly from those that are naturally found on the plant waste.