Arbejdsrapport fra Miljøstyrelsen, 3/2004 – Reduceret brug af kvælstof og pesticider - økonomisk og miljømæssig effekt

Reduceret brug af kvælstof og pesticider

Summary and conclusions

In 2001 the Danish Agricultural Advisory Service, LandboNord Farm Consulting & Accounting and the National Centre/Crop Production started a project demonstrating the effect of reduced use of nitrogen fertilizer and no use of pesticides. The demonstrations were carried out at two farms.

The purpose of the project was to demonstrate that it is possible to secure an effective agricultural production in the field and - at the same time - to protect the groundwater against pollution with nitrate and pesticides.

In spring 2001 six demonstration fields were established at two farms in the northern part of Jutland. In each of the fields two subfields were established, each of approximately one hectare. One subfield was cultivated with normal crop rotation for the farm, and the other was cultivated with a special rotation aiming at minimising nitrate leaching. In the subfield with normal crop rotation normal soil cultivation was compared with reduced soil cultivation.

In the demonstration fields nitrogen fertilisation according to the standards for the crops and for plant protection was compared to the reduced nitrogen fertilisation (60 pct. of the norms) with and without chemical plant protection.

No use of chemical plant protection resulted in a substantial reduction of economic income, especially for winter wheat. On the other hand, for spring barley the economic yield was not reduced. The reason for the reduction of the economic income was a large population of weeds, especially in 2002, caused by the lack of plant protection in 2001.

In the demonstration fields cover crops appeared to be an effective way to reduce nitrate leaching. On the other hand, the reduction of nitrogen fertiliser and reduced soil cultivation had no or only a very small effect on nitrate leaching.

In general, the results of the project show that in many cases reduced use of nitrogen fertiliser and pesticides did not cause severe reduction of the economic income from spring barley, whereas for winter wheat, the economic yield was severely reduced.

Together with results from other projects, the results from the demonstration project show how best to protect the groundwater in vulnerable zones, and what the economic consequences are. Tesults from this project can, however, not stand alone, as they are based on experience gained from only six fields in only two years.