Over 300,000 hectares of the best land in Ireland is engaged in tillage farming, or the annual production of crops for harvest. Cereal crops are the main output, led by barley, then wheat and then oats. Did You Know: The pounds of feed (grain, forage, etc.) a dairy cow needs to eat to produce 100 pounds of milk has decreased by more than 40% on average in the last 40 years.