I tried the Dutch Clover cover crop between rows 5-6 years ago. I sowed the Clover, then marked out rows, and planted I'm thinking sweet corn in that spot. The National Weather Service predicted a 70% chance of rain that evening, so I figured it'd be a good time. Rain went just to the South of here, with a few sprinkles dotting the dust. Then, no rain for about a week. Apparently enough moisture in the ground to sprout weeds, but not enough for clover or sweet corn. About 10 days, and sweet corn was spiking, and clover just sprouting in the very small 2 leaf stage. By then, the weeds were getting big, so I cultivated,and killed most of the clover.
If I ever try it again, since I now have a Brinly planter, I'll sow the clover 14-20 days ahead of time, then plant whatever into the stand of clover. The reason for sowing the clover was a two-fold plan. A living mulch, and a nurse crop supplying N for the corn Looked good on paper, Mother Nature fooled us again.