According to the last national agricultural census, there were 1.6 million farms in 2010 (-32.4% since 2000) covering 12.7 million hectares (63% of which are located in Southern Italy). The vast majority (99%) are family-operated and small, averaging only 8 hectares in size. Of the total surface area in agricultural use (forestry excluded), grain fields take up 31%, olive tree orchards 8.2%, vineyards 5.4%, citrus orchards 3.8%, sugar beets 1.7%, and horticulture 2.4%. The remainder is primarily dedicated to pastures (25.9%) and feed grains (11.6%). The northern part of Italy produces primarily Maize, rice, sugar beets, soybeans, meat, fruits and dairy products, while the South specializes in wheat and citrus fruits. Livestock includes 6 million head of cattle, 8.6 million head of swine, 6.8 million head of sheep, and 0.9 million head of goats. The total annual production of the Fishing industry by country from capture and aquaculture, including crustaceans and molluscs, is around 480,000 tons.
Question: Which takes up more total surface area in agricultural use, grain fields, or olive tree orchards?
Answer: grain fields