Convoys of oxcarts loaded with gunnysacks of rice seed move along the roads in this western province, evidence that the first phase of emergency relief efforts to get seed to Cambodian farmers in time to plant this month and next is succeeding.

While distribution of desperately needed food aid remains painfully slow, foreign aid workers in Phnom Penh report that the Heng Samrin government has moved the initial seed shipments -- the basis for hopes that Cambodia will be able to feed itself at least partially next year -- with unprecedented speed.

The long-delayed shipments are the subject of endless debate among aid workers in the capital, because seed is seen as the key to agricultural recovery. If large quantities of seed are late, the harvest at the end of this year will be drastically reduced, forcing Cambodia to seek that much more food abroad in 1981.

But questions remain whether the government's transportation network, blamed in part for the slow arrival of food to the village level, can maintain this momentum in the coming weeks.

Seed is on the farmers' minds, too. A bit is left from last year and people have been told the government will provide. But so far, only a few farmers have received any. One farmer in Outapong village, 20 miles from the port of Kompong Som, was asked if he would plant this year. "We have no seed. I can't plan for the future. We have to live day-by-day," he replied.

U.N. and private relief groups plan to bring in over 21,000 tons of seed by early June at points controlled by the Vietnamese-supported Heng Samrin government. Hanoi has pledged an additional 10,000 tons. Meanwhile, foreign agencies in Thailand have passed out about 13,000 tons to people who come to the border.

Conversations with oxcart drivers along Battambang roads revealed most got their seed at the border. But random checks at villages in the province show seed was also arriving from Phnom Penh.

Agronomists hope that farmers, using both foreign and domestic seed, will plant vast expanses of paddyland -- perhaps as much as 3.75 million acres. As the rice is tended to maturity, the country will need about 250,000 tons of food in 1980, relief workers say, to make up for rice the fields did not produce last year.

Seed shipments began two months late because of export licensing problems in Thailand and lack of funds. By the time seed was cleared to go, relief agencies decided to airlift the program's 5,000 tons of "floating rice" seed to Phnom Penh airport at a cost of $5 million.

This was necessary, specialists said, because floating rice, used in areas where flooding is deep, must be planted in April or May, while other varieties normally go into the ground in June.

In Phnom Penh, foreign aid officials were relieved to find the government had cleared almost every logistical bottleneck in the distribution network. "They understand the priority," said one foreigner. One hundred trucks were assigned to the project. They loaded seed at the airport, then took it directly to the countryside or to Phnom Penh rail station for transport to Battambang Province in the west.

Under prodding from relief agencies, the government agreed to keep the seed moving during public holidays.

By April 19, about 1,100 of 1,800 tons earmarked for Battambang had reached the province, and most had been distributed to the district level, foreign workers were told. Other shipments were directed to provinces closer to Phnom Penh.

Plans called for ships to begin arriving early this month to keep filling the pipeline as the airlift ended.

Aid workers in Phnom Penh acknowledge that for the seed program to work, Phnom Penh must keep its distribution network performing at an emergency pitch. But they maintain this is feasible because Cambodian officials and their Vietnamese advisers understand the importance of seed.

If food shortages continue past 1981, it is argued, Phnom Penh will risk political troubles at home and have increasing difficulty blaming the shortages on the former Khmer Rouge government, deposed by Vietnamese troops in January 1979.

Good harvests would mean the departure of the international agencies, whose presence and continued assistance is a political embarrassment, aid workers said.

Still, other signs suggested Phnom Penh's logistical difficulties are not entirely cleared up. The director of Kompong Som port, in an interview 10 days before the first seed shipment was scheduled to arrive, was unable to say what steps he would take to assure prompt unloading or how much seed the port would handle.

In Thailand, where most of the seed is being purchased, many foreign aid officials argue that Phnom Penh cannot be relied upon to get the rice out in time. Huge quantities of seed should be sent across the Thai border, they feel. Although most will go only as far as Battambang Province, the country's largest rice producer before the wars that brought the communists to power, some will be carried to other areas.

Interviews in Battambang with cart drivers indicated a few were taking border seed to two neighboring provinces.

More than 13,000 tons of seed have been passed out along the border already, and plans call for 250 tons per day. While refusing to open an official land route from Thailand because of its continued recognition of the Khmer Rouge regime, Phnom Penh has turned a blind eye to the enormous traffic of carts that the frontier is attracting.

Relief workers in Phnom Penh generally condemn the border handouts as unnecessary and a potential source of political friction in dealings with the government there.

"The border operation is not coordinated with us and we don't want it to be," said one official working in the seed effort. His own agency was participating in border distribution from Bangkok, he said, but he did not know how much was coming across.

Even if seed does reach the villages in time, uncertainties remain over the farmers' ability to till the land. Buffaloes, which pull many of the country's plows, are estimated to have numbered 2.5 million in 1968, but only 800,000 today.

To this pessimists add shortages of farm implements and fertilizer, and such psychological factors as whether farmers will work the fields if they believe free food will be available at the border or district warehouse.

Optimists in Phnom Penh say the country will turn the corner in 1981. Pessimists, say 1983, if then. But most say it is too early to tell.