erosion, 8.6 percent by salinity and sodicity, and 8.6 percent by flooding and ponding; fully 96 percent suffer from less-than-adequate organic matter. These problems often occur simultaneously and produce synergistic impacts on agricultural productivity. Soils can suffer from both water and wind erosion, and poor organic-matter content is universal, reducing the potential productivity of the best as well as the worst of soils.Water. An arid and semi-arid country, Pakistan's water sources have always been limited. The country has regularly experienced critical water shortages, which lead to power blackouts and also to inadequate supplies of irrigation water for the main crop-growing season. To compensate, a finely balanced system of water management for irrigation, electricity, and industry has been developed. The system is shaped in part by the Indus Waters Treaty. Signed in 1960 by India and Pakistan following long-standing water disputes, the treaty gives Pakistan control over the Indus and its western tributaries the Jhelum and Chenab, while India controls the Ravi, Beas, and Sutlej branches in the east. The treaty also allowed Pakistan to construct two large storage and hydroelectric dams: the Tarbela on the Indus and the Mangala on the Jhelum, as well as a system of smaller dams, inter river canals, and irrigation canals. This irrigation network now services about 16 percent of the country and is one of the largest such systems in the world. As much as 65 percent of agricultural land is irrigated, accounting for about 90 percent of the country's food and fiber production.Approximately 175 billion cubic meters of water enters the Indus Basin annually. Of this, 128 billion cubic meters is diverted for irrigation purposes to the canal heads, while remaining water flows to the sea. Although this flow to the sea is needed to maintain a viable river ecosystem, especially in the Indus estuary, experts agree that much of it could be store...
