Decomposition stops when a pile is too dry and becomes anaerobic if too wet. Nitrogen is necessary for decomposition to occur. Rotted oak leaves and pine needles are only slightly more acidic when fully decomposed. There are usually enough microorganisms on leaf surfaces, in the soil on roots of weeds, etc. for decomposition to occur. This means 25 parts carbon to 1 part nitrogen.
Small pieces break down more rapidly and give a more even result.
Small quantities of kitchen or yard waste can also be buried 12 inches deep at intervals throughout the garden. For neatness and efficiency, a bin or container may be desired. When a bin is filled, the contents will heat up to 140 F or higher, accelerating the decomposition process and possibly destroying disease organisms and weed seeds. A pile taller than 5 feet may weigh itself down and drive out oxygen creating an anaerobic condition. They can be individual bins, called holding bins , where materials are added and held until they decompose, a relatively slow process.