Encourage the diversity surrounding the farm. The ecology of your farm does not end at the property lines.
Plant trees around the farm that act as windbreaks and also provide habitat for local birds (which can prey on insects that prey on crops).
Tolerate natural predators that keep pests at bay (for example, snakes that feed on gophers, ladybugs that feed on aphids, spiders that feed on insects which spread diseases to crops).