The piles were about three feet high. She started new piles in the fall and winter. During the winter microbes that decay compost are not very active. But the moist conditions along with the freezing and thawing soften the course materials. Food wastes dissolve down into the course material.
Manure helps fuel the composting process when the weather warms.
Mother said she was seeding the pile with the old compost or dirt since they contain the necessary composting organisms With warmer spring temperatures and rains, compost heats up and the microbes use up the most readily available nutrients and moisture. Adding fresh yard and garden wastes at this time keeps the pile working. It leads to a more uniform, finished compost. A smelly pile is to wet and needs more course material and more regular mixing. A pile that is to dry will have a dry center and needs more moisture, green clippings or a few shovel fulls of moist dirt.