13 January 2015

Crops can do their own weed control

Weed control Weeds are the enemy of crops and agricultural output worldwide. Organic and conventional farmers have their respective weed control strategies, either through the use of fuel guzzling, CO2 producing machines or environmentally harmful chemicals. Research from the University of Copenhagen now suggests that the war on weeds can be conducted more sustainably by asjusting sowing patterns and crop density.

Wheat sowed in a field with high weed pressure provided by rapeseed. Left photo: Low crop density, crops sowed in rows. Middle photo: High crop density, crops sowed in rows. Right photo: High crop density, crops sowed in grid pattern.

In conventional farming, the most frequently used herbicides for weed control have a negative impact on the environment. On the other hand, organic farmers enlist machines to battle unwanted growth. These machines guzzle fuel and produce CO2, while their tyres compact soil and damage its structure. New research results from the University of Copenhagen’s Department of Plant and Environmental Sciences report that weeds would have a tough time competing against crops such as corn, grains and beans if farmers were to alter their sowing patterns.

“Our results demonstrate that weed control in fields is aided by abandoning traditional seed sowing techniques. Farmers around the world generally sow their crops in rows. Our studies with wheat and corn show that tighter sowing in grid patterns supresses weed growth. This provides increased crop yields in fields prone to heavy amounts of weeds,” states Professor Jacob Weiner, a University of Copenhagen plant ecologist.

Weeds battered, crop yields bumped

Research studies performed in Danish wheat fields, together with recent studies in Colombian cornfields, demonstrate that modified sowing patterns and the nearer spacing of crops results in a reduction of total weed biomass. The amount of weeds was heavily reduced – by up to 72% – while grain yields increased by more than 45% in heavily weed-infested fields. The trick is to increase crop-weed competition and utilize the crop's head start, so that it gains a large competitive advantage over the neighbouring weeds.

Jacob Weiner explains:

- Our results make it possible for agriculture to be conducted in a far more sustainable manner while maintaining consistently high grain production. This requires affordable new technologies to make it proactical out in farmers' fields. We can develop methods for outcompeting weeds even more if we learn more about how plants interact.

The research results from Colombia have just been published in Weed Research, one of the leading scientific journals in its area. They were achieved via a collaborative effort between the Jorge Tadeo Lozano University in Colombia and the University of Copenhagen.

Link to article: Effects of density and sowing pattern on weed suppression and grain yield in three varieties of maize under high weed pressure

For further information:

Professor Jacob Weiner

Department of Plant and Environmental Science

Phone: +45 35332822/+45 42680644

Mail: jw@plen.ku.dk

Communications officer Rikke Pape Thomsen

Department of Plant and Environmental Science

Phone: +45 35 33 35 19

Mail: rpt@plen.ku.dk