1.5 million tons of soy, 862 thousand tons of sunflower seed, 829 thousand tons of apple, 726 thousand tons of onion, 537 thousand tons of tomato, 474 thousand tons of lemon, 445 thousand tons of grapefruit, 444 thousand tons of banana, 421 thousand tons of barley, in addition to smaller productions of other agricultural products, such as avocado, pineapple, peach, tangerine, pumpkin, cabbage, carrot, rapeseed, sorghum etc. The agricultural industry contributes around 5% of formal employment, relatively low compared to other parts of Africa, as well as providing work for casual labourers and contributing around 2.8% of GDP for the nation. However, due to the aridity of the land, only 13.5% can be used for crop production, and only 3% is considered high potential land. The sector continues to face problems, with increased foreign competition and crime being two of the major challenges for the industry. The government has been accused of either putting in too much effort, or not enough effort, to tackle the problem of farm attacks as opposed to other forms of violent crime. Maize production, which contributes to a 36% majority of the gross value of South Africa's field crops, has also experienced negative effects due to climate change. The estimated value of loss, which takes into consideration scenarios with and without the carbon dioxide fertilization effect, ranges between tens and hundreds of millions of Rands. According to FAOSTAT, South Africa is one of world's largest producers of: chicory roots (4th); grapefruit (4th); cereals (5th); green maize and maize (7th); castor oil seed (9th); pears (9th); sisal (10th); fibre crops (10th). In the first quarter of 2010, the agricultural sector earned export revenues for R10.1 billion and used R8.4 billion to pay for imported agricultural products, therefore earning a positive trade balance of R1.7 billion. The most important agricultural exports of South Africa include: edible fruit and nuts, beverages, preserved food, tobacco, cereals, wool not carded or combed, miscellaneous food, sugar, meat, milling products, malt and starch. These products accounted for over 80% of agricultural export revenue in the first quarter of 2010. The most important agricultural imports, which accounted for over 60% of agricultural import value during the same period, include: cereals, meat, soya-bean oil cake, beverages, soya-bean oil and its fractions, tobacco, palm oil and its fractions, miscellaneous food, spices, coffee, tea, and preserved food. The dairy industry consists of around 4,300 milk producers