I have been down the road with soybean plots several times. I have had plots ranging from 1/2 acre to 3 acres. At 1/2 to 1 acre, the deer literally mowed down the plot...when I say "mowed", it literally looked like a mower had gone over it and cut everything back to a height of 2-3 inches. Anything in a retention cage went up over a foot. At about 2 acres, the plot was better, but still suffered a lot of browse. As a side note: I have good habitat (plenty of acorns, plenty of crops around the area including corn, beans, alfalfa) but the smaller plots seem to really get hammered.

What did seem to help was planting a decent sized plot of clover on each side of the beans. It seemed to take some of the browsing pressure off the beans.