they will graze on fallow land, eating weeds and grasses, depositing fertilizer and tilling the land with their hooves in the process
Almost literally as it's described by John Seymour! Ok he talks about pigs, but there's not that much difference - quote: To say nothing of the fact that pigs are the finest free cultivators that were ever invented! They will clear your land, and plough it, and dung it, and harrow it, and leave it nearly ready for you to put your seed in, with no more labour to you than the occasional shifting of an electric fence