Traditional plows would become gunked-up with soil, forcing farmers to repeatedly stop and clear away soil. Moldboard plows repel soil, lowering the cost of farming.
John Deere was an ordinary blacksmith, creating pitchforks and other common farm instruments. Farmers complained about the time wasted stopping and clearing their plows. Deere thought there must be a better solution. He reasoned that a differently shaped plow, with a polished steel end, would naturally repel soil.
Iron was more common than steel, so Deere melted down an old sawblade. He iteratively worked with different shapes until finding one that slid through the soil. By polishing it, soil slid off rather than building up.
“Deere must have given a great deal of thought to the shape, to the special curve of his moldboard, for its exact contours would determine just how well the soil would be turned over after the share had made the cut.”
Smithsonian curator Edward Kendall after testing an 1838 Deere plow.
Deere sold his plows first locally then further away. Within a decade, he was selling 2,000 plows per year. Twenty years later, sales continued booming and Deere offered nine different models depending upon a farmer’s needs.