Speaking at a seminar held in An Giang Province last week, they said the country had become one of the world's top rice exporters with the help of favourable natural conditions and the government's support policies, but poor management of the fertiliser market had caused losses for farmers.
Dr. Mai Thi Anh Tuyet, deputy director of the An Giang Province's Science and Technology Department, said the use of mineral fertiliser on Vietnamese fields had increased year by year, from 40 kilos per hectare in 1976-1981, to 120 kilos in 1982-1988, and to 140-150 kilos now.
The use of plant protection chemicals has also increased, as shown by the local pesticide industry's average annual growth rate of five per cent in recent years. In 2009, the country used a total of 8 million tonnes of fertiliser and 50,000 tonnes of plant protection chemicals, she said.
Despite the need for such large volumes of fertiliser and pesticide, the domestic fertiliser market still relies mostly on imported products.
Most domestic producers must import raw materials to make fertiliser, which raises production costs.
Between 2001 and this year, the market had imported 60 per cent of urea fertiliser and 100 per cent of imported fused calcium magnesium phosphate (FMP), ammonium sulphate (SA) and Kali fertilisers, Tuyet said.
Multi-layered distribution networks, together with weak oversight by market management agencies, are also factors that have significantly raised prices of fertilisers and pesticides, and led to a preponderance of low-quality products on the market.
Fertiliser and pesticide company agents are receiving 20 and 40 per cent commission compared with the producers'prices.
As a result, many kinds of agricultural materials have had prices raised by 30 and 40 per cent compared with the factory rates charged directly to farmers.
Bui Ba Bong, deputy minister of Agriculture and Rural Development, also stressed the need to apply strict fines or penalties on those who produce or trade in fake or low-quality fertilisers and pesticides.
Fertiliser manufacturers who doctor their products for profit will be fined up to VND150 million (US$8,000) by inspectors from the ministries of Industry and Trade and Agriculture and Rural Development, according to officials.
Phung Ha, head of the Viet Nam Chemical Agency, said this was the first time the two ministries had been authorised to punish fertiliser companies that broke the law.
"There have been an increasing number of cases of fake fertilisers being sold on the market," Ha said.
He said that last year a fertiliser manufacturer in the Central Highlands had used salt to bulk up the volume of its product with the result that hectares of coffee plantations were ruined. In 2008, he said inspectors analysed one product and found that it contained no nitrogen at all, the basic constituent of fertiliser.
Inspections, which started on Monday, are slated to finish by the end of this month.
Officials said provincial authorities should be more rigorous with their checks before issuing business permits.
"In many provinces, authorities only care about a company's capital when issuing a permit." Ha said.
He added that the Government wanted to eradicate bad practices and reassure consumers.
Nguyen Hac Thuy, chairman of the Viet Nam Fertiliser Association, doubted that the inspection programme would be effective.
"Government regulations state that firms must be given seven days prior notice before inspections are carried out. That means that companies have enough time to cover their tracks," Thuy said.
Ha said that inspectors often had to be circumspect when investigating companies suspected of doctoring their products.
"We often have to be subtle when carrying out inspections. For example, we might have to get fertiliser samples without the firm's knowledge," he said.
Out of 270 products inspected during the first six months of last year by the Ministry of Agriculture and Rural Development, 110 were found to be substandard.
The domestic market consumes about 9.1 million tonnes of fertiliser a year. Of that, 3.3 million is imported, according to the Ministry of Industry and Trade.