RE: Crop Rotation
Rob,
I' ve planted buckwheat a couple times. Its best as a spring planting, as a summer forage, and the deer really eat on it hard when the seeds are just forming 8-10 weeks from planting. They will eat the whole tops (which will be about shoulder height with good soil). In my experience, once the seeds turn brown and get hard, the deer stop eating it - and birds & mice come from all over. If its still growing at first frost (mid september in NY where I am), its done after that. In fact - frost will lay it flat right on the ground (good for mice and birds, but not deer in Mid Oct).
July planted buckwheat will offer some forage in the end of August/beginning of sept. It could be the seeds will not ever get hard when July planted. But do not count on it as a fall forage after the 1st frost. Again, I Like buckwheat for the massive root structure (read sod-buster) in a new planting, and for how easily it breaks down in the soil - a great first planting on sod heavy soil.