A little fine-tuning will put food on all our tables

Organic farming won't feed the world, and its environmental benefits are overrated, say Louise Fresco et al

World governments have committed themselves to a double challenge. At the Earth Summit in Rio de Janeiro in 1992, they agreed to pursue sustainability. Ecologically speaking we are living beyond our means, with 60 per cent of the world's natural ecosystems under threat, mostly for use as farmland. In 1996 these same governments declared an intention to reduce world hunger by half over the next few decades. This, as well as expected population growth, is going to need more farmland.

As World Environment Day approaches it is important to examine the claims of organic farming against this background. The organic movement argues that by reverting to more traditional methods the negative impact on the environment will be less than that of intensive farming. In fact, the opposite is true: by denying the benefits of modern agricultural technology, organic farming is inherently less efficient, with a more negative impact on the environment than its science-based counterpart.

The main challenge for all farming is soil fertility. Crops absorb nutrients from the soil. Many soils quickly lose essential nutrients, which leads to a reduction in yield, water retention and can lead to erosion.

Organic farming dictates that lost nutrients can only be replaced by traditional methods, such as compost, manure or nitrogen-fixing plants.

This requires a great deal of land to lie fallow or be used for grazing.

The disadvantage of using manure or compost is that they do not lend themselves to fine-tuning. Chemical fertiliser, however, can be tweaked to supply a plant's exact nutritional requirements at any given time in its growth cycle.

In the past excessive use of fertiliser (and manure) has led to environmental problems. This does not mean that normal farming methods are inherently bad. Gradually the "more means better" paradigm is being replaced by a refined management of agricultural ecosystems. Artificial and natural fertilisers are used together when crops require an extra boost of, for example, elemental nitrogen.

Organic farming excludes pesticides and promotes the use of natural enemies and naturally occurring compounds for pest control for the sake of biodiversity. It is true that biodiversity on organic farmland may be greater than on high-production farmland, but the number of species still does not come near that found in, say, the rainforest, or even the humble British marshland. Even ignoring the extra land required, it is questionable whether organic farming is significantly better for the environment.

Pesticides have been improved. Research has made them more selective and biodegradable, reducing their negative environmental impact. Modern agriculture is beginning to use natural enemies, especially in horticulture. This integrated pest management is becoming standard practice, such as the use of "flowering fields" - areas of land that provide shelter for natural enemies of pests. This is particularly relevant to smallholders in the developing world, who cannot afford to lose crops or buy large quantities of chemical fertiliser or pesticide.

Ecological modernisation of agriculture over the past 25 years has been a great success. Yields per acre, per kilogram of fertiliser, litre of water and man-hour are increasing. Ten years ago it was calculated that in Europe the same levels of produce could be obtained with 20 per cent less fertiliser, 80 per cent less pesticide and 30 per cent less farmland.

Slowly but surely this is coming true through the use of precision farming and refinement of crops using genetic techniques. Restrictions on artificial fertilisers, synthetic pesticides and modern genetic techniques make an efficient use of resources impossible in this sector.

Organic produce constitutes a valuable niche market, but we should be under no illusion that this type of low-yield farming will help to meet the increasing demands on the world's food supply.

Conventional agriculture has learned lessons from the past and from organic farming. Rather than taking opposing views we must all work together to employ the whole arsenal of available techniques to develop modern farming.

Louise Fresco is assistant director general of the Food and Agriculture Organisation of the United Nations and distinguished professor at Wageningen University, the Netherlands. Rudy Rabbinge is dean of Wageningen Graduate Schools and university professor at Wageningen. Joost van Kasteren is a science writer in the Netherlands. Translation by Harriet Teare and Sander van Kasteren, both organic chemists at Oxford University.

The views represented here are those of the authors and not the FAO.