In built-up areas, however, yard waste needs to be managed deliberately. In the spring and fall when grass clippings and leaves appear in great amount, yard waste can comprise as much as half of the overall collection. Some communities require yard waste to be bagged separately from other waste fractions. Unlike mixed garbage or sewage sludge, separately collected yard waste can be composted effectively through simple, low cost, methodologies . Essentially, given a suitable site, the major steps may be as follows.
Windrow length depends on site configuration.
Over the course of 12-16 months, the material is transformed, through the action of indigenous, beneficial, microbes, to earthy, stabilized, compost. For every ton of yard waste received, about half a ton of compost is produced. Compost derived from mixed garbage, and especially from sewage sludge, may contain pathogenic, disease-causing, organisms, and potentially harmful levels of heavy metals. Yard waste cannot be said to be invariably free of such problems as, for example, with leaves spending time underneath a car with a leaky crankcase. But in general compost derived from yard waste need not be suspect and may be considered safe for use in the most sensitive of applications, as in the vegetable garden.