Organic matter, such as animal waste and plant residues, which has been actively decomposed in a closely managed process involving aeration and mechanical mixing achieving appropriate time and temperature points. Compost is the product of a managed process (treatment, turning, etc) through which microorganisms break down plant and animal materials into more available forms suitable for application to the soil as a fertilizer. According to EPA, compost must be produced through a process which combines plant and animal materials with an initial Carbon:Nitrogen ratio of between 25:1 and 40:1. Producers using an in-vessel or static aerated pile system must maintain the composting materials at a temperature between 131°F and 170° F for 3 days. Producers using a windrow system must maintain the composting materials at a temperature between 131°F and 170° F for 15 days, during which time the materials must be turned a minimum of five times.