One important part of organic farming is feeding the land. Conventional farming makes sure there are enough nutrients in the soil to sustain their crops and pastures by adding chemical nutrients directly to the ground.
Organic farmers choose not to use these chemicals, but simply skipping this step would leave the soil without enough nutrients for healthy growing plants. And without healthy plants to eat the animals suffer as well. This is an important chain on the farm--from the soil to the plants to the animals.
Luckily there is another very natural link in that chain that helps complete the nutrient cycle. Animal manure is a natural food for the soil and all the little critters that help keep the soil healthy--from the dung beetle down to soil microorganisms.
This is part of what makes rotational grazing such a wonderful way to farm. The animals remove plants and nutrients from the soil when they graze, but also do a wonderful job of spreading their own manure and its fertility as they move through the pasture, feeding the soil that is feeding them.
Every year we make hay on some of our pasture land so our animals will have good feed for the winter when they can't graze. This land has missed some of the benefit of animal manure during the growing season so we make sure to spread any bedding we collect in the barns back on those areas that need it most. In addition we feed our winter hay to the animals right on the fields that need the fertility. Come spring the hens help us out by turning the leftover feed and manure, and spreading the nutrients across the pasture.
That is the beauty of a system that works for everyone!