Features Agronomy Insect Pests
Crops can do their own weed control

Jan. 13, 2015 - 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 tires 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 per cent – while grain yields increased by more than 45 per cent 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 practical out in farmers' fields. We can develop methods for out-competing 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.

Wheat sowed in a field with high weed pressure provided by rapeseed. Left photo: Low crop density Research from the University of Copenhagen now suggests that the war on weeds can be conducted more sustainably by adjusting sowing patterns and crop density.