The US plans to spend about $500 million next year fighting opium traffic in Afghanistan. It probably won't work any better than it did in previous years, maybe worse. At current prices, the "farm gate" price of the entire opium crop is about $560-$760 million, which is not really all that much more than we will pay in trying to use military force to eradicate it.
It seems to me that the Afghani farmer might be amenable to a classic American-style soil bank: in other words, we will pay them about what they would have earned growing opium not to grow it. And, it would cost us about what we would have paid trying to force them not to.
When I was in high school, after my dad retired from almost 30 years in the Marines, he satisfied a desire that he had had from when he was a little kid and lived on a farm with his mom & dad (both of whom died when he was young). He bought a small farm in Preston, GA (not far from Plains). He was able to do this because over half of the land was in the soil bank, meaning that he was able to get an income from the property without growing crops. In his case, it was even more strange, because apparently what people did fairly often in that area was to start a bunch of pine trees, put the land in the soil bank until they were of a proper size for making paper or whatever they make out of pine trees, take it out of the soil bank for a year, harvest the trees, and then put it back in. Kind of silly when you think about it. The rest of the land was in pecan orchards, and we did gather and sell pecans for (not much) money. This only lasted a short time, because my dad up and died before things really got going on our farm. Anyway, that was my exposure to the soil bank.
What if every Afghan farmer who would currently either grow or would be tempted to grow opium were given the oppurtunity to do what my dad did: put some or all of his land into the American soil bank, get enough income to satisfy basic needs with it, and grow something more interesting on the rest of the land (do pecans grow in Afghanistan?--probably not).
Actually, there really is no need for a "bank" of unproductive land in Afghanistan: instead, the money payments would be for them not to grow opium. They would be free to grow anything else on the land, but they would be free of worries regarding their survival while they were gearing to to grow wheat, tea, corn, or pecans. This is a little like what my dad did with the pine trees.
There could still be a role for soldiers, because there would be repercussions of a policy like that. The drug lords would try to scare the farmers into continuing to grow opium, and of course the price would go way up. But wouldn't it be more satisfactory for US troops to be protecting farmers from predatory narcotraffickers, than going around destroying their crops?