Pakistan's aging irrigation infrastructure and years of little rain are adding up to major problems for farmers, prompting the government to subsidize a new drip-style irrigation system. But some farmers still find it too costly to install.

Pakistan's tribal areas. Graphic by Michael Harry. Pakistan's border region with Afghanistan is a rugged, mountainous area that has attracted militants and insurgents -- and become a target for Pakistani military operations and U.S. drone attacks. A number of…