Published 20.12.2022
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Strip cropping has great potential
Strip cropping attempts to mimic the principles of natural ecosystems while maintaining high productivity.
The dominant landscape element in Denmark is increasingly larger and more efficiently managed fields of mainly monoculture farming. The large, uniform cultivation areas form fertile ground for epidemic attacks by pests such as insects and fungi, which in organic farming can cause very serious losses in yield and crop quality.
Strip cropping suggests cultivating narrow strips with different crops next to each other on the same field and utilising positive neighbour effects between different crops to create robust farming systems and enhance bio-diversity.
Strip cropping field trials have demonstrated an increase in overall biodiversity and the number of beneficial insects, higher yields of different crops, slower development of pest and disease attacks and less soil structural damage. Among other effects, a significant reduction of and delay in the development of potato blight has been found in potatoes grown in strip cropping systems rather than monoculture.
Strip cropping can provide:
- robust crops
- enhanced biodiversity
- higher and more stable yields
- delayed/reduced fungal and insect attacks
- fertile soil
- less erosion and soil compaction
- increased landscape value
Strip cropping can be put into practice in many ways
The general purpose of strip cropping is to create variety. The more crops, the greater the possibilities for variation.
There are many ways in which strip cropping can be incorporated into a crop rotation in a field. The design does not have to be particularly complex. If a simple design is desired, a good start is to introduce a new crop in the crop rotation so that two crops are included in a strip cropping system for one year. (see figure).
It is also possible to combine two crops that are already part of the crop rotation, so that two crops are grown in a strip cropping system for two years of the crop rotation. If all the crops in the rotation are paired two by two, the crops in pairs switch places after half the time of the crop rotation.
If greater variety is desired, more than two crops can be cultivated in the field each year. The full variety is achieved if all crops of the crop rotation are grown in a strip cropping system on the field each year.
Figure: There are many ways in which strip cultivation can be incorporated into the crop rotation of the field. Here are five examples of a six-year crop rotation. A regular crop rotation is shown at the far left, and a gradual increase in spatial diversity is shown towards the further right of the figure. Source: Isabella Selin Norén, Wageningen University.
The right neighbours
When practicing strip cropping, carrying out the fieldwork by smaller tractors and machines is a clear advantage, but no special equipment is needed to get started. The width of each strip is determined by the required working widths of the available machines. The narrower the strips, the greater the neighbour effect and the diversity effect.
Which crops are good neighbours is one of the big questions that needs to be resolved before the strip cropping system can be upscaled and depends on e.g. the growing season of the crop, soil cover and expected interactions.
By choosing plants with different development and morphology, the utilization of nutrients, water and light can be improved. The more diverse crops are chosen, the greater variety is offered to the beneficial organisms of the field.
At the same time, natural enemies are supported if a suitable soil cover is cultivated in the neighbouring strip, to which the insects can migrate during disturbances such as tillage, weed control and harvesting.
Trials in Denmark
In Denmark, strip cropping is practiced in trials by farmers and on research plots. Researchers are investigating the effects of strip cropping on e.g. pests, beneficial animals, diseases and yield.
One of the big questions that needs to be addressed, however, is first and foremost whether strip cropping can be put into practice by Danish farmers. In 2022, strip cropping systems were established at two organic farms using the farmers’ own machinery.
At one of the farms, located in the middle part of Denmark, potato is the main crop. Nine-meter strips of potatoes, peas, flowers, and spring barley are established there. The other farmer grows blackcurrants in nine-meter rows and has agricultural crops in an eight-meter system between the berries.
The hope is that strip cropping systems adapted to local conditions will be developed in Denmark in a setup in which crop yield and quality are less affected by devastating diseases and pests.
Various versions of strip cropping systems adapted to Danish organic farming are being tested in several places in the country. The picture shows an experimental setup in Lolland, where beet, quinoa, horse beans, peas, spring barley, oats, spring wheat and spring rye are grown in three- and six-meter strips. Photo: Nordic Beet Research Foundation.
Conclusion
- In a strip cropping system, fields are cultivated in narrow strips with different crops that are cultivated next to each other.
- The strip cropping system provides spatial diversity in a field, which can enhance biodiversity and create a more robust system.
- Strip cropping systems are investigated in field trials in Denmark with the aim of creating suitable living conditions for robust populations of beneficial animals and increase resistance to disease.
