Chamla Valley, Northwest Pakistan, and Bogota, Colombia — Tall and thin, and wearing a long white shirt and baggy trousers, Pathan tribesman Mahman Dullah left his two-bullock plow and described how he was about to harvest half an acre of sugar cane on his best patch of ground.
He was no ordinary farmer. He and thousands of other Pakistani farmers are being watched with intense interest in New York, Washington, London Dublin, Boon , Rome, Vienna, and other capitals.
Until recently, Mahman and his family grew opium poppies. His were part of 9, 000 acres of poppies in the Buner district of Pakistan's North-West Frontier Province, five hours by twisting, mountainous road from Islamabad, and formerly the single largest poppy-growing area in the country.
Now a government prohibition order is backed by armed force. He had to plant another cash crop than wheat, which is his subsistence crop. Thanks to advice and seeds from a United Nations development program, he has turned to sugar cane.
The result: He says he is growing no poppies at all this year. The government says no poppies are being grown in Buner as a whole.
Can this be a crucial answer to world drug supplies - cutting them off in the very fields where they grow?
Well - maybe. There are plenty of skeptics - some recent West German visitors to the area, for instance.
They say poppies are still grown within sight of some Pakistani military facilities, that local tribal leaders, police, and military connive to continue growing poppies, that farmers are easily able to grow them closer to the Afghanistan border where government authority is virtually nonexistent, that farmers like Mahman do not tell the truth to strangers.
Even some UN officials in Vienna worry that it is hard to be sure that farmers are not simply planting poppy fields near the Afghan border areas to escape government agents.
It certainly remains true that the major loophole in this region is Afghanistan, whose Pathan tribesmen still produce as many as 300 metric tons of opium a year. They funnel both opium and refined heroin to Europe and North America via Pakistan and India.
Nonetheless, the UN program here has made at least some forward steps in rural development and in irrigation. It has begun to widen farmers' vision from poppies to other crops.
This, then is one way being tried to reduce supplies of drugs: rural development including substituting more conventional crops for opium poppies.
United States and UN officials recognize that it is a long and difficult process, but they say it is well worthwhile. The further drug crops move from the fields where they grow the more difficult they are to intercept and seize. With every step in the illicit distribution network, organic drugs are refined into smaller more concentrated quantities, easier to conceal and increasing greatly in value.
As well as substituting other crops, there is one other way to shut off supplies at the source: eradication by digging up or spraying. Eradication of coca in Columbia
On the eastern Andean slopes of Columbia, young coca-leaf bushes spread like a green tide over 30,000 to 40,000 acres. Along the northern coastal strip of the Guajira, marijuana flourishes.
In Bogota, cocaine addiction has suddenly erupted like a flame. Only two years ago, there were almost no cocaine addicts here. Now US officials estimate there are hundreds of thousands.
The US, which receives 90 percent of its illicit cocaine and 60 percent of its marijuana from Colombia, wants President Belisario Betancur to start serious digging up of coca plants and massive aerial spraying of marijuana. But the necessary approval order for spraying is still lying on the President's desk, unsigned.
Pressures on the President not to sign come from the wealthy and powerful ''cocaine cartel'' in Columbia which generates some $2 billion a year in illicit drug traffic.
Another worry by those who want tougher action: President Betancur is a leading member of the four-nation Contadora group (Colombia, Mexico, Panama, and Venezuela) that is trying to mediate in Central America. President Reagan wants the group's support - and is under pressure to reduce US pressure on the drug trade to get it.
''Rural development takes time,'' says Donnelly A. Sohlin, who is deputy executive director of the United Nations Fund for Drug Abuse Control (UNFDAC) in Vienna.
''Effective law enforcement against growing is essential. Only then can new crops and rural development take root.''
With a tiny budget of $9.5 million a year, UNFDAC nonetheless has 20 projects around the world, including crop substitution programs in Pakistan, Thailand, and Burma, and others on law enforcement and health.
The fund uses no UN money but relies on contributions. So far the bulk of the money has come from the US ($2 million a year), Sweden, Norway, West Germany, and Japan.
The fund's biggest news for many years is that Italy pledged in November this year to provide $40 million over the next five years to reduce supplies of coca leaves (and thus cocaine) from the Andes in South America.
Prodded by the Italian director of the fund, Judge Giuseppe de Gennaro, the Rome government has acted partly because members of the Italian Mafia are actively organizing cocaine traffic in Bolivia and Peru.
The fund is expected to use the virtual doubling of its budget to extract higher contributions from other donors.
The US also has State Department and foreign aid rural development programs in Peru, Bolivia, Colombia, Mexico, Haiti, Thailand, Pakistan, and Turkey. Crop substitution in Thailand
The Thais have six programs, trying to substitute coffee, kidney beans, potatoes, and other crops for opium poppies: the Netherlands has set up a coffee research station, Canada, West Germany, and the US have projects, and UNFDAC has a highland marketing and production scheme. Australia has provided a computer.
The UN is certain it has demonstrated that coffee and kidney beans can be successful replacement crops in Thailand. The US State Dept. is much more skeptical, saying the Thai government has not done nearly enough to ban poppy growing.
Norwegian Church Aid has provided $1.5 million since 1971 for a highland marketing program in Thailand. Norway supports UN projects in Burma. Church groups in West Germany contribute to the United Nations fund - and the Japanese Ship Building Industry Foundation has given fund projects a total of $860,000.
The UNFDAC program in Buner in the dust and poverty of mountainous northwest Pakistan illustrates both the triumphs and trials involved in replacing opium poppies with more legitimate crops.
Gale Day, a cheerful American who is UN field adviser in Pakistan, admits that many mistakes were made in the project's first phase (1976-81).
Tube wells were sunk for irrigation, but farmers were left to work out their own irrigation canal systems in their fields. Still permitted to grow poppies at the time, they didn't bother to dig the canals.
''Miracle'' replacement crops were tried - mint, garlic, saffron, tea, walnuts, apples, oranges - but farmers either could not grow them or could not sell them.
Not much really happened until the Pakistani government began in earnest to enforce its 1979 ''hadd'' (prohibition) order against poppy growing.
At the same time, high 1979 prices for opium began to plummet. Opium, morphine, and refined heroin flooded in with refugees after the Soviet invasion of Afghanistan.
For its part, the UN had learned some lessons. Its new on-site senior adviser , Tom Mulder of the Netherlands, says the next phase is to push more irrigation water to more fields, and to build more roads.
At current low opium prices, Mr. Mulder estimates, farm families in the Chamla Valley can make more money from two crops on irrigated land - tobacco and sugar cane - than from poppies on nonirrigated land. Tobacco can earn a family 4 ,282 rupees ($329) per irrigated acre, and sugarcane 1,382 rupees ($106) an acre.
Clearly, irrigation is the key. Poppies are still way ahead of all other money crops on nonirrigated land: 1,054 rupees for poppies, against 657 rupees for wheat.
Not all farmers are as fortunate as Mahman Dullah. Irrigation has not yet reached his land on the valley floor, but he has adequate ground water for sugarcane.
Obstacles remain high. Only 5,000 of the Buner's 135,000 acres are irrigated. Tube wells cost $80,000 each, including expensive diesel engines. The major task for the UN is to persuade the Pakistan government to run electricity into the Chamla Valley. Markets must also be kept open for tobacco, sugar cane, and other new crops.
In the old days, he said, clandestine opium buyers gave him credit at the local shop. In 1979 he received a record high price for his opium, four times higher than the current price of $30 a kilo (2.2 lbs.).
If opium prices rise or if a future government ease up on law enforcement to win votes, UN efforts could be in trouble. However, the value of irrigation seems to have sunk in, thanks largely to Mulder and his two assistants, Dutch agronomist Jan Poulisse and Italian irrigation engineer Giovanni Quaglia.
UN figures show nonirrigated land in Buner district is worth 5,000 rupees ($ 384) an acre, whereas leveled and irrigated land is fetching 60,000 rupees ($4, 615) an acre. Asia's biggest opium producers
The two big opium loopholes now are Afghanistan and Southeast Asia's ''Golden Triangle'' area where Burma, Laos, and Thailand intersect.
Afghanistan still produces 300 tons of opium a year, and some experts say privately that Pakistani production is considerably higher than reported. The high volume has lowered prices. Soviet troops in Afghanistan either cannot or will not stop poppy growing or cheap but effective heroin refining labs.
Burma generates 500 tons of opium, according to the US State Dept., in hill areas roamed by 5,000-man armies belonging to warlord Khun Sa, to the Burmese Communist Party, and to a former Chiang Kai-shek general. Recent visitors say it is beyond the power of Rangoon or Bangkok to control the illegal trade.
At the end of 1982 US Attorney-General William French Smith visited the North-West Frontier Province and told the governor, Lt. Gen. Fazle Haq, that the US (already providing Pakistan $3.2 billion in military aid) expected more to be done.
By June of this year Pakistan was claiming that 41 illegal laboratories had been ''smashed.'' In fact, the labs had been surrendered by Afridi tribesmen. Rival Shinwari tribes refused to stop refining and at least one shoot-out occurred.
US officials including the Drug Enforcement Agency's Doug Wankel were finally allowed to see the surrendered labs. They consisted of old buckets and tubing - no refining chemicals, no opium, no heroin.
''There are labs working on the Afghan side, at Jalalabad and Torkham,'' Mr. Wankel said in an interview in Islamabad.
US officials say the government well knows who the major Pakistani traffickers are. But in three years it has not arrested a single one. Heroin addiction in Pakistan
One other development in drug growing countries may turn out to be the most significant of all: rising local addiction rates which are leading to louder protests at home.
Into a small room in a one-story building in the Karachi slum of Lyari (population: about 1 million) flock Pakistanis with staring eyes and shambling steps. Some of them are well-educated, eager to shed the heroin habit.
''They thought heroin was something like charas (hashish), which people here have smoked for ages,'' explained Bernadette Dean, a Pakistani social worker of Portuguese descent as she greeted patients in the only heroin outpatient treatment center in the country.
A man in a gray shirt told me brokenly that he had a master's degree in Islamic history. He had run his own marble business, but a pusher gave him some free heroin three years ago, and he had become addicted.
''Heroin is hitting the middle classes now,'' Dr. Zaheer Khan of Karachi's Civil Hospital said.
''When it was just poor people, it was ignored. Now parents with influence in government and the media pay attention. We now have 100,000 addicts in Karachi alone, double my estimate of just two months ago. . . .''