The Ankole, which produce little milk and leaner meat, could also be extinct throughout the century. Their digestive system has advanced to process grasses and different crops. Corn and other grains trigger a cow’s digestive system to become acidic. Irrigated agriculture represents 20 percent of the total cultivated land and contributes forty percent of the entire meals produced worldwide. Irrigated agriculture is, on common, at least twice as productive per unit of land as rainfed agriculture, thereby permitting for more production intensification and crop diversification. Many of these were adopted over the next century or so throughout Europe. For instance, the Norfolk four-field system, developed in England, proved quite successful. It concerned the yearly rotation of several crops, including wheat, turnips, barley, clover, and ryegrass. This added nutrients to the soil, enabling farmers to develop enough to sell some of their harvest with out having to go away any land unplante