Farming has changed since 1930. I know your history textbooks stopped covering it then (for good reason, after 1930 farming hasn't been significant), but that doesn't mean farming has stood still. Plowing as practiced in your history books is out of style and only rarely done. Farmers are well aware that soil washed away is gone forever, and are working to conserve it. Farmers are aware that fertilizer is a significant cost and what washes off is wasted money. No-til, strip til or other minimal till farming is the normal for many farmers. Cover crops are fast becoming popular. The old plows often are sold for scrape when in perfectly good shape (plows wear out fast in use)