Big agricultural companies say the next revolution on the farm will come from feeding data gathered by tractors and other machinery into computers that tell farmers how to increase their output of crops like corn and soybeans.

Monsanto Co., DuPont Co. and other companies are racing to roll out "prescriptive planting" technology to farmers across the U.S. who know from years of experience that tiny adjustments in planting depth or the distance between crop rows can make a big difference in revenue at harvest time.

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