The American military is expanding its efforts to rebuild Afghanistan's agriculture after decades of war left the nation's farm-based economy in ruins.

Once a major exporter of dried fruits, nuts and exotic crops such as pomegranates, Afghanistan is now known mainly for growing poppies for the opium trade.

Many farmers who knew how to successfully raise food crops were killed or fled the country during the past three decades, said Col. Martin Leppert, who oversees the Army National Guard's Afghan agribusiness effort from offices in Arlington, Va.

"Imagine if everyone who was a farmer got up and left Kansas _ we'd have to re-teach those people who are still there. That's what we're trying to do in Afghanistan," Leppert said.

The military began sending agribusiness units to Afghanistan in early 2008. They now work in 14 of the nation's 34 provinces, where they are trying to improve irrigation and water management practices and bring new ideas to farmers who eke out a living much as American farmers did 150 years ago.

A 63-member Indiana Guard unit returned last week from an 11-month mission to Khowst province, which borders Pakistan. A second Indiana unit is already in place in that province to carry on the farmer education work.

Col. Brian Copes, the commander of the 1-19th Agribusiness Development Team, said a big part of the unit's 11-month mission was training agricultural extension agents in each of the province's 13 districts to better perform their jobs.

Each agent learned to use a $2,500 soil-testing kit left in his care to enable him to test local farmers' soils to determine how much fertilizer or other treatments their land needs.

Sgt. Maj. Scott Bassett, one of the unit's 15 agriculture specialists, said soil tests in the province revealed many farmers are using more than twice the amount of fertilizer needed on their fields _ and over-application is reducing yields.

The unit trained 50 farmers in each of the 13 districts in new approaches, such as how to irrigate fields using drip hoses that deliver water to crops while conserving the precious resource during the region's long dry season.

To show the benefits of using less fertilizer and other new methods, the unit is paying one farmer to grow half of his crops Afghan-style and the other half the American way.

When that farmer's fields are harvested this year, the hope is the advantages of the new methods will be readily apparent to him and his neighbors.