Pakistan's economy is heavily dependent upon agriculture, which accounts for a quarter of the gross domestic product (GDP) and employs over half the population. Most of the agriculture relies on water supplied through some 64000 kilometres (40,000 miles) of irrigation canals, almost all of which are on the Indus plain. Rising salinity, caused by poor drainage, is a growing problem, affecting about half of all irrigated land.
Wheat is the principal food crop, followed by rice, millet, maize, barley and pulses. Cotton is by far the most important cash crop and accounts for five percent of world production. High-quality Basmati rice, grown mainly in Lahore Division, is also a major export. Other major crops include sugar-cane, oil-seeds (mustard, rape, sesame, linseed and castor), tobacco, fodder, fruit (citrus, mangoes, bananas, pomegranates, apples and apricots, among others), and vegetables such as potatoes, onions and chillies