Hi, you might be interested in this article on Low-tech Magazine, Bring back the horses, which argues that it would be a good move to replace tractors by horses in agriculture.
Because nowadays agriculture is largely based on fossil fuels (they are needed for the manufacture of artificial fertilizers and tractors, and for the operation of tractors) food security is in danger now that oil prices keep rising.
Horses produce their own fertilizer and they reproduce themselves. They need no fuel. The article links to some scientific studies which state that switching from tractors to horses is realistic and a win-win situation, even when taken into account the extra cropland needed to feed them
Main problem is that there are not enough horses and that we should start breeding them fast.
What do you think?