Wetenschap - 1 januari 1970

Bulb industry in search of environmentally friendly cultivation

Bulb industry in search of environmentally friendly cultivation

Bulb industry in search of environmentally friendly cultivation

Bulb cultivation is one of the most polluting forms of agriculture. Bulb growers are doing their best to reduce pesticide and fertilizer losses, but they still have some way to go

Any self-respecting tourist who visits the Netherlands comes in the spring to see the bulb fields. From Wageningen this means going west. Bulbs require fertile and well-drained soil. Along the coast between The Hague and Haarlem and in North Holland around Castricum and Limmen the conditions are ideal. Bulb growing however is gradually spreading to other areas of the Netherlands. It is a lucrative business despite the drawbacks. Rotation with other crops would reduce pressure on the environment, but lack of space in the West prevents this. Spreading to other areas is one solution

The Netherlands is the largest flower bulb producer in the world, devoting a total of 20,000 hectares to bulbs and cut flowers for export. That is two thirds of the total bulb area worldwide. The tulip upholds its position as the symbol of Holland by taking up 10,000 hectares. While the area under bulb cultivation is still on the increase, the number of farms involved is decreasing. At the beginning of the 1960s there were some 16,000 bulb growers; by 1998 there were just 3,000 growers

A large amount of pesticides is needed to ensure that a bulb reaches countries like Japan in perfect shape and disease-free. The use of crop protection measures is high. Bulb growers spray an average of 23 kg of active substances over one hectare of tulips. Only fruit trees, roses and chrysanthemums receive higher amounts, with lilies topping the list at 117 kg per hectare. The bulb sector as a whole uses an average of 78 kg of active substance per hectare. The amount used on tulips is in the same league as the amounts used for seed potatoes (20 kg). In contrast, another important field crop in the Netherlands, sugar beet, uses a mere 3 kg of active substance per hectare. Fertilizer and pesticide use has been considerably reduced in recent years. In 1987 the bulb sector still used 120 kg per hectare, but further reductions are deemed necessary. The goal set by the government for 1995 has not yet been reached, never mind the figure for 2000 (48 kg per hectare)

It is relatively easy to measure the amount of fertilizers and pesticides which are used. However quantity does not necessarily indicate the extent of effect on the environment. It is much more important to know which toxic substances the growers are using. The Centre for Agriculture and Environment (CLM) in Utrecht has devised a method for measuring this. The CLM has examined the effect of all pesticides and fertilizers on water organisms, soil organisms and ground water. The results of this study indicate that all three aspects of the environment were worse off in 1997 than in 1994 and 1996. This negative effect is due to just a few insecticides which are particularly damaging. Another problem is the amount of pesticides which are washed away into the surface water. On this point the bulb growers score badly, often overstepping the limits. Measurements indicate that five substances (three fungicides and two insecticides) are responsible for 90% of the offences. Fertilizer use tends to stay within the limits set. Growers are allowed to apply 100 kg of phosphates per hectare. On average they use 80 kg per hectare, but there are exceptions. Twelve per cent of the growers exceed the limits. A ceiling for nitrogen use has not yet been set. Use has declined anyway, from 325 kg per hectare in 1994 to 210 kg per hectare in 1997

The bulb growers themselves are aware that they have to move with the times. Research is on hand to help: The Laboratory for Flower Bulb Research in Lisse (LBO) now forms part of Wageningen UR and carries out research on ways of reducing the amounts of fertilizer and pesticides used. Researchers have developed a warning system for blight in lilies. This system enables a grower to treat plants only when necessary, which saves on pesticide use. The LBO is now working on similar systems for tulips and gladioli. Members of the Chair Group of Theoretical Production Ecology at the University have collaborated with the DLO Institute for Agrobiology and Soil Fertility (AB-DLO) to develop models to help make bulb cultivation more environmentally friendly. The growers remain wary. They are under pressure from Japan and the US to deliver perfect bulbs. In order to try and overcome the wariness of the growers, the project Bulb growing after 2000 has been established. Twenty-four bulb growers are participating and are doing everything they can to keep the losses of pesticides and fertilizer to a minimum. The idea is that these growers provide an example for their fellow bulb growers. L.N