Grass is a third category and is piled separately. When materials are combined for composting, wood chips or leaves can serve as the base of the windrows. This dry, high-carbon source needs to be mixed with manure or grass clippings, both of which contribute nitrogen. The leaf-manure mixture will compost well on its own. But they monitor their windrows, especially for temperature.
Thermometers protrude from windrows.
If we didn't, we'd be in trouble because we don't use any herbicides on our crops. The thermometers also tell when the windrows have reached a stable temperature and can be stockpiled for spreading. They have invested money in the project. Not only does it take acreage, it takes machines. They have a tractor with front-end loader, a compost turner, a grinder for wood and a screener to remove undesirable materials from the finished material.