Ever gazed on beautiful green fields with cows or sheep grazing in the sunshine? The verdant green grass seems to feed the hungry animals without ever receiving anything in return and once they have moved on, it quickly regrows and seems none the worse for the experience. Yet that’s not the whole picture.
As they feed, the animals digest the grass and deposit it back in the form of manure and urea (in copious quantities if you’ve ever walked over one of those fields). It might be unintentional, but they put back much of what they take as they graze. A myriad of organisms works on the manure and incorporates it into the soil, which is enriched and rejuvenated. Fallen leaves and rotting vegetation add still further to the rich mix of humus and nutrients; all part of nature’s natural cycle.