Very interesting tale of two cities in The Long War Journal, with especial emphasis on the opium economy and its currency - opium paste.
A typical farm in the area uses a 100-meter well that extracts water from the ground with an electric submersible pump powered by a diesel generator. This system – limited by the cost of the fuel to run the generator – is suited for modest subsistence farming and ranching, but not the more extensive flood irrigation required for most business agriculture. An exception to this rule is poppy, which requires less water per acre while providing a greater profit margin than alternatives like wheat and corn. The illegal crop has additional advantages: bricks of opium paste can be stored for up to five years; the Taliban and other drug lords will pick up poppy from farmers, removing the hurdle of prohibitively expensive distribution; and the bricks can be used as cash to buy goods and services.
“Any bazaar will accept poppy as cash at a daily spot market rate in payment for anything from kids’ shoes, to land rent, to medical care. It’s the currency of the realm,” explained one American expert who declined to be named. “And water is so expensive, once it’s lifted to the surface, poppy is the only crop that is profitable enough to justify the expense, and there is enough profit left to grow a subsistence amount of wheat to feed the family and maybe sell a little bit on the side.”