by KEITH REID

The fertilizer industry, naturally, focuses on the benefits of fertilizer use, going so far as to claim that the natural environment would suffer if agricultural inputs were reduced. Environmental groups, on the other hand, focus exclusively on the harm caused by nutrients in the environment. Both sides make valid points, so how do we sort out the balance between the two?

Nothing that we do is completely without risk, so the worth of any activity is measured by whether it provides enough benefit to justify the risk. Most of the time, we are weighing our personal risks and benefits for something that we are planning to do, but the same model can be used for societal issues. Complications occur when the perceived risks are intangible, or when the risks accrue to all of society, while the benefits are all to individuals.

This is often the case with nutrients, where the benefit of higher crop yields go to the farmer, while the cost of impaired water quality or reduced species diversity happen somewhere downstream. Despite these challenges, a case can be made to balance the societal risks and benefits of fertilizer use, ignoring for the moment the direct economic costs and benefits to the farmer.

The risks from nutrient use include potential nitrate contamination of groundwater, eutrophication of surface water from nitrogen or phosphorus loading, and fish kills from ammonia addition to surface water. There are other indirect risks attributed to fertilizer use, but these should not be considered since they have no direct connection to nutrients, other than that they result from agricultural systems made possible by the use of mineral fertilizers. These include factors such as loss of species diversity, soil erosion and loss of soil quality.

On the benefits side of the ledger, the increased productivity from fields receiving adequate nutrients means that fewer acres are needed for a given amount of production. This leaves more acres free for other land uses, including wildlife habitat and buffer strips. Vigorous crop growth also increases the input of organic matter into the soil, which increases the density of crop cover and protects the soil from erosion by wind and water.

The unique thing about nutrients in the soil is that both the risks and the benefits depend on the concentrations of the nutrients, but the relationship is not linear. The risk of pollution by nutrients depends on their movement off the field, which means either transport with the soil or leaching from the field.

Where soil erosion from a field is occurring because of poor crop cover, adding fertilizer to improve crop growth could actually reduce the amount of nutrient reaching the stream. Adding fertilizer above levels where the crop responds, though, will increase the risk of leaching losses. The benefits to the crop of added fertilizer increase up to a threshold level, and beyond that there is no further yield increase. In extreme cases, extra fertilizer can actually hurt the crop and reduce yields. The greatest benefit from the lowest risk is going to occur with moderate nutrient additions.

How about organic? Organic agriculture is often considered to be environmentally benign, and it may be if it is managed properly, but the lack of commercial fertilizer is not enough on its own to guarantee there will be no off-site impacts from crop production.

The key point overlooked by some proponents is that it is the quantity of nutrients applied, rather than the form, that dictates the risk to the environment. Composted manure applied to a legume sod, and then plowed down in late summer to allow weed control by tillage, can pose a greater risk of nitrate leaching than a similar amount of nitrogen applied as anhydrous ammonia, either preplant or sidedress.

The other hidden risk factor with organic agriculture is that it depends on the cycling of nutrients, and every natural cycle is, inevitably, leaky. Even the tightest systems will have some loss, with the milk, meat or crops that are sold off the farm. If these nutrients are not replaced from some outside source, the productivity of these fields will eventually decline.

Sound nutrient management is the key. Too much or too little fertilizer is bad for the environment. The key to minimizing environmental risks from nutrients is to match the nutrient additions (from all sources) to the crop needs. Good economic crop management is generally also good environmental crop management. BF

by NORMAN DUNN

For a start, small and extremely mobile bands of anti-GM activists who give themselves the above description have successfully destroyed acres of genetically modified crop trials from the Scottish Highlands to Bavaria this year, as they did last year and the years before.

This kind of pressure seems to have convinced most European governments to continue their veto on commercial GM crop growing. Spain, on the other hand, has never had any real problem with GM crops and this summer some 50,000 acres of Bt-corn are being grown there.

Meanwhile, the British farmers who have actually been hosting GM trials on their land may have shown some initial scepticism sceptical about the benefits of herbicide-resistant oilseed rape and sugar beet. But a survey showed this attitude has quickly changed. A 70 per cent swing towards approval has been recorded and, by this year, 90 per cent of the farmers involved were absolutely in favour of commercial GM cropping.

Of course, this doesn't answer popular fears that eating food derived from GM crops might affect human health. But as one irate grower in Scotland wrote in the national farming press recently, "A billion people have eaten GM food over the past eight years with no ill effects."

European consumers may soon be in the position to join these millions because the European Union has approved legislation to allow appropriately identified GM-derived foods in the stores soon. This could be great news for countries exporting GM crops to Europe but, under the present politics, leaves home producers with an expanding market, which they are not permitted to supply.

Another problem is the present effort by pressure groups in Britain to stop farmers spraying in the vicinity of houses. There are two points of importance here. First, most crop growers in Britain are pretty intensive producers with a high dependence on herbicides and fungicides for targeted yields, such as three to four tonnes of wheat per acre. Second, many farmers there have already established a voluntary no-spray margin -- generally from 10 to 20 metres --where homes are in the vicinity of fields. But skilful lobbying in parliament has encouraged the government to propose new legislation that might a no-spray margin of up to 300 metres.

One such pressure group, the Pesticides Action Network (PAN) estimates that there are more than five million people living in the British countryside, a quarter of a million with houses next to fields which are regularly and "intensively" sprayed. Growers have already reacted by saying such legislation would put them right out of business as intensive grain, oilseed, sugar beet or potato growers. The government reckons that the 300-metre no-spray margin would affect around 3.5 million acres of arable crops.

Britain's Department for Environment, Food and Rural Affairs (DEFRA) is now collecting reactions to the proposal and indicates that it wants to be reasonable. For instance, it suggests that there could be an argument for a much smaller no-spray margin, maybe just 100 metres or less. Also, ways of finding financial compensation for the affected farmers may be possible.

Most farmers, however, are pretty cynical about this collection of reactions prior to legislation. They know that it is the pressure groups that will provide the opinions and this is why many growers are already preparing to cut down their spraying soon -- by a wide margin.

As always, it's the "them and us" attitude and the lack of communication and understanding between agriculture and non-farmers in overcrowded Europe, which leads to such confrontations. But many have seen the danger signals and opened up their farms for school visits and public open days.

Others, like Bavarian wheat grower Otto Funck, are making real money out of showing visitors that even commercial wheat crops are so safe you can sleep in them. Otto runs what is probably Europe's first "wheat field hotel." Natural conditions in the German countryside mean this is only open for two weeks in August just before harvest every year.

For $15 Cdn, the night visitors get a huge barbeque and a secluded mown "room" in a wheat field with plenty of straw to bed down in. Own sleeping bags are recommended. Also included is a farmhouse breakfast with local produce only, accompanied by discussions on farming and its problems -- including relations with non-farmers and the growing influence of pressure groups. BF

Norman Dunn writes about European agriculture from Germany.