Windrow composting is a method of composting organic matter in long, triangular or trapezoidal heaps that are turned periodically to allow aeration and accelerate decomposition. This method is frequently used for large-scale composting operations, such as on farms or in municipal composting facilities.
At the start of composting in open heaps, biodegradable waste, agricultural residues, manure, etc. are piled up in long rows, typically 2.5 to 5 meters wide and 1.2 to 2.5 meters high. The rows are left for a few days to allow the internal temperature of the stack to rise, typically to around 50 to 70 degrees Celsius. The first “hot” stages of the composting process are important to kill any harmful bacteria or pathogens in the organic material and to speed up the entire process.

During the composting phases, the heaps must be turned over with a special compost turner that loosens and aerates the heap. Turning the pile also helps regulate the internal temperature and moisture content of the compost. The process of moving and controlling the pile takes anywhere from several weeks to several months, depending on the size of the windrow and the type of organic material being composted. Once the compost is fully degraded and stabilized, it can be used as a soil conditioner for agricultural or landscaping purposes, or as a feedstock for organic fertilizers.

The shape and size of the windrows depends on the type of compost turner, as does the layout of the composting facility.
Input volume, process time and space availability are considerations for choosing the right type of compost turner. The volume of material in process, the process duration as well as the turning frequency and machine running time determine the size and capacity requirements.