<P> Watermills were introduced by the Romans, but were improved throughout the Middle Ages, along with windmills, and used to grind grains into flour, to cut wood and to process flax and wool . </P> <P> Crops included wheat, rye, barley and oats . Peas, beans, and vetches became common from the 13th century onward as a fodder crop for animals and also for their nitrogen - fixation fertilizing properties . Crop yields peaked in the 13th century, and stayed more or less steady until the 18th century . Though the limitations of medieval farming were once thought to have provided a ceiling for the population growth in the Middle Ages, recent studies have shown that the technology of medieval agriculture was always sufficient for the needs of the people under normal circumstances, and that it was only during exceptionally harsh times, such as the terrible weather of 1315--17, that the needs of the population could not be met . </P> <P> After 1492, a global exchange of previously local crops and livestock breeds occurred . Maize, potatoes, sweet potatoes and manioc were the key crops that spread from the New World to the Old, while varieties of wheat, barley, rice and turnips traveled from the Old World to the New . There had been few livestock species in the New World, with horses, cattle, sheep and goats being completely unknown before their arrival with Old World settlers . Crops moving in both directions across the Atlantic Ocean caused population growth around the world and a lasting effect on many cultures . Maize and cassava were introduced from Brazil into Africa by Portuguese traders in the 16th century, becoming staple foods, replacing native African crops . </P> <P> After its introduction from South America to Spain in the late 1500s, the potato became a staple crop throughout Europe by the late 1700s . The potato allowed farmers to produce more food, and initially added variety to the European diet . The increased supply of food reduced disease, increased births and reduced mortality, causing a population boom throughout the British Empire, the US and Europe . The introduction of the potato also brought about the first intensive use of fertilizer, in the form of guano imported to Europe from Peru, and the first artificial pesticide, in the form of an arsenic compound used to fight Colorado potato beetles . Before the adoption of the potato as a major crop, the dependence on grain had caused repetitive regional and national famines when the crops failed, including 17 major famines in England between 1523 and 1623 . The resulting dependence on the potato however caused the European Potato Failure, a disastrous crop failure from disease that resulted in widespread famine and the death of over one million people in Ireland alone . </P>

Where was the agriculture developed in the new world