Afghanistan is appealing for $142m (£92m) to feed 2.6 million people this winter as it faces the worst drought for a decade.
The agriculture minister described the situation as extremely serious, with 14 provinces - about half the country - in the north and east hit by drought.
Many farmers have sold their livestock and will now depend on food aid to keep alive during winter.
The World Food Programme has issued an urgent appeal for assistance.
Agriculture Minister Mohammed Asif Rahimi said that Afghanistan had not been able to develop the systems necessary to deal with shocks like this on its own.
"Lower harvests due to drought, and rising food prices world-wide, have created an emergency for Afghans in the north," he said, adding that food support would be needed for the next six months.
Shortfall in aid
An extra 2.6 million hungry people would bring Afghanistan's total to nearly 10 million. The World Food Programme says it is already facing a shortfall in food aid as an earlier appeal was not answered in full.
Farmers in villages in the northeast told the BBC's international development correspondent David Loyn that it was worse than 2001 - the last very dry year.
In many areas wells have dried up, and people will have to move off their land to survive.
The Taliban and other insurgents have been making strong gains in recent years in the drought-affected areas, particularly in the north-east, which is likely to affect the delivery of food supplies to those who need them, our correspondent says.
Mr Rahimi listed the drought-hit provinces as Balkh, Samangan, Takhar, Saripul, Herat, Badghis, Faryab, Jowzjan, Baghlan, Kunduz, Badakshan, Bamiyan, Daikundi and Ghor.