Bacteria harnessed to solve wine-farm pollution problems

Printed in: Farmer's Weekly, 15 June 2001

With an increase in intensive farming, getting rid of smelly effluents has become a problem, even in the wine industry. A soil and irrigation expert discusses a new way to get rid of this waste.

The use of intensive-farming methods is giving way to smelly effluents that are generally associated with factory farming, where the disposal of manure and other wastes is an increasing problem. Nowadays even "clean" agriculture, such as the wine farms of the Western Cape, is contributing to the pollution of our environment.

Dr Jean Piaget, one of South Africa’s foremost authorities on soils and irrigation, says he has seen streams running red with winery waste water. He says he is concerned about both the unnecessary waste of water and the fact that the effluent is so acid that it is bound to harm aquatic life and users lower down the stream.

Dr Jean Piaget is one of South Africa's foremost authorities on irrigation and water quality

Despite his concern, he says the problem is not difficult to deal with. A system that uses microbes to clean the effluent and air bubbles provided by air "injectors" may be the solution.

However, these injectors are imported from America. Farmers have to pay for them in dollars, and sometimes they have to be matched to heavy-duty macerating pumps that can cope with the detritus in ponds filled with untreated wash water. Many farmers draw the line because they say the pumps are too expensive.

"Wine farmers will happily spend many thousands of Rands on stainless-steel plumbing and imported oak vats," Dr Piaget says, "but when it comes to cleaning up the mess they make, they unfortunately become a tight-fisted bunch. They don’t see the disposal of effluent as important.

"What we need is a complete change of attitude. Waste products have to be managed as intensively as every other aspect of intensive farming."

He says farmers should learn how to help nature dispose of agricultural wastes. If the right methods and equipment are used, ponds can become smaller and deeper. They can be more conveniently sited, and free more land for cultivation.

Although effluent disposal might not be a priority for farmers at present, the scarcity of water will soon convince them that steps need to be taken to rectify the situation. Farmers see water as a precious resource and respect it. If it is used to hose down floors or transport wastes, then there is an obligation to clean up the water afterwards so that it is not returned to the environment in a polluted form.

Since the world export markets opened up to SA wines a few years ago, modern irrigation methods, such as drip lines and micro-systems, have not only made land more productive but enabled farmers to cultivate mountain sides and even small pockets of land in semi-urban areas.

SA farmers have proved they are quick to adopt new methods, especially when it comes to water conservation. One example he quotes is the use of plastic sheets that are laid on the land in broad strips. The vines are then planted in holes in the plastic. The method keeps the moisture in the soil, and competing weeds don’t grow in the darkness under the black plastic. Initially farmers were skeptical. Even when the technique was demonstrated on alternate rows in the same field with dramatic results there were reservations.

"They told me that to produce good wine a vine must struggle," he says. "The plastic made it too easy for the root stock, and the quality would suffer, but these fears have proved groundless, and today the use of plastic sheeting is an accepted practice."

SA farmers were also quick to use drip-line irrigation. "In fact they were too quick and were using the system before we understood how to space the drippers to suit the soil conditions," he says. "The initial results were sometimes disappointing, but farmers were not put off, and drip-lines are now making a comeback."

South Africa also invented micro-irrigation. Dr Piaget helped to pioneer the system. "A mining engineer came up with the idea as a way to keep mine dumps damp to solve the dust problem" he says. "It worked so well and it used so little water that the agricultural potential was quickly realised by a local farmer. The rest of the world learned from South Africa."

Dr Piaget says SA farmers have been quick to embrace ways to get the best possible value out of the country’s scarce water resources, but they have not been prepared to take a holistic view of intensive farming. He says they spend money on modern irrigation equipment to put good water into the vineyards, but they are not easily prepared to spend money on the treatment of their effluent.

Lack of suitable training in effluent disposal may be one of the reasons why wine farmers are not dealing with their waste effectively. Dr Piaget says he has pointed out many times that viticulture students in Stellenbosch receive too little training in effluent disposal despite the fact that it is a vital part of wine making.

Training wine makers-to-be in effluent disposal is one thing, but getting them to put the knowledge into practice is another.

"I hope the necessary courses have been introduced," Dr Piaget says, "but even if they have, it will still take a long time before the knowledge is out there on the farms."

He tells the story of how he received a lecture from an American traffic cop after he had parked in a "blue for disabled" parking bay near a hotel. The gist of the cop’s message was that "in America NO means NO".

"That’s what we have to learn in South Africa," he says. "When we lay down the law on how water can be used and how our streams and rivers must be kept free of pollution NO must mean NO." — by Tony Robinson