This has been heroin's great heartland, where the narcotic came to life as an opium resin taken from fragile buds of red and white poppies. Last year, 75 percent of the world's opium crop was grown in Afghanistan, with the biggest yield sprouting from here in the fertile plains of the country's south, sustained by the meander of the Helmand River.

But something astonishing has become evident with this spring's harvest. Behind the narrow dikes of packed earth, the fields are empty of their most profitable plant. Poor farmers, scythes in hand, stoop among brown stems.

Mile after mile, there is only a dry stubble of wheat to cut from the lumpy soil.

Last July, the ruling Taliban banned the growing of poppies as a sin against the teachings of Islam. The edict was issued by Mullah Muhammad Omar, referred to as Amir-ul-Momineen, the supreme leader of the faithful.

Almost every farmer complied, some grudgingly, some not. ''Even if it means my children die, I will obey my amir,'' said Nur Ali, sitting in his fields, sipping tea. Like most Afghan men, he wore a turban coiled around his head like a holy bandage. ''And the day my amir says I can grow poppy again, I will do that too,'' he said.