Keep plants and animals around that indirectly benefit the farm's stability and productivity. For example, yarrow and nettles add to the nutritional value of plants grown near them, as well as increase the volatile oil content of plants grown for oils. Plant extra basil to serve as an insecticide, and keep guinea fowl around to keep ticks at bay. As they roam your farm (and the surrounding countryside), guineas eat the ticks left by browsing deer off tall grasses. They are traditionally reputed to kill or keep rattlesnakes away as well.