Weeds are a major scourge for organic growers, who often must invest in multiple control methods to protect crop yields. A relatively new weed control method known as abrasive weeding, or "weed blasting," could give organic growers another tool. The method, recently field-tested at the University of Illinois, is surprisingly effective.
In conjunction with plastic mulch, abrasive weeding reduced final weed biomass by 69 to 97 percent compared to non-weeded control plots, said U of I agroecologist Samuel Wortman.
Abrasive weeding involves blasting weed seedlings with tiny fragments of organic grit, using an air compressor. For the current study, grit was applied through a hand-held siphon-fed sand-blasting unit connected to a gas-powered air compressor, which was hauled down crop rows with a walk-behind tractor.
The study looked at a number of grit sources: walnut shells, granulated maize cob, greensand, and soybean meal. If applied at the right plant growth stage, the force of the abrasive grit severely damages stems and leaves of weed seedlings.
Wortman found no significant differences between the grit types in terms of efficacy. "When it leaves the nozzle, it's at least Mach 1 [767 mph]," Wortman noted. "The stuff comes out so fast, it doesn't really matter what the shape of the particle is." Because ricocheting particles can pose a risk to the applicator, Wortman advises using protective eyewear.
Blasted grit does not discriminate between weed and crop seedlings, which makes it important to use this method in transplanted crops that are substantially larger than weed seedlings at the time of grit application. Although some visible damage occurred on stems and leaves of both tomato and pepper crops, the damage did not affect marketable fruit yield. Studies are ongoing to determine whether abrasions on crop tissues could result in increased susceptibility to disease, but early results show little effect.
Importantly, plots with plastic mulch and one or more blasting treatment achieved the same fruit yields seen in hand-weeded plots, and 33 to 44 percent greater yields than in non-weeded control plots.
An additional benefit of weed blasting is the potential for growers to use organic fertilizers, such as soybean meal, as blasting material. "We expect that abrasive weeding could contribute between 35 and 105 kg nitrogen per hectare [31 - 94 lbs per acre] to soil fertility." The idea that a grower could both fertilize and kill weeds in a single pass is appealing, but it is still unknown whether the fertilizer would be available for plant uptake within critical windows.
According to Wortman's research, weed blasting does affect some weeds more than others. Essentially, the smaller the seedling, the better. Also, seedlings whose growing points are aboveground (annual broadleaf species) are more susceptible to blasting than seedlings whose growing tips are located belowground (grasses and broadleaf perennials). Finally, Wortman noted that the presence of plastic mulch seemed to factor strongly into the equation. Weed blasting alone "is not a silver bullet, but it is an improvement," he said.
The method is now being tested in different horticultural crops, including broccoli and kale, with and without additional weed control methods. Early results suggest that the presence of polyethylene mulch or biodegradable plastic mulch strongly enhances the success of weed blasting, as compared with straw mulch and bare soil. Wortman and his collaborators have also developed a mechanized grit applicator, which they are currently testing.
The paper, "Air-propelled abrasive grits reduce weed abundance and increase yields in organic vegetable production," was published in Crop Protection. Funding was provided by the National Institute of Food and Agriculture's Organic Agriculture Research and Extension Initiative. The article can be found online at http://www.
Lauren Quinn | EurekAlert!
Researchers discover natural product that could lead to new class of commercial herbicide
16.07.2018 | UCLA Samueli School of Engineering
Advance warning system via cell phone app: Avoiding extreme weather damage in agriculture
12.07.2018 | Leibniz-Zentrum für Agrarlandschaftsforschung (ZALF) e.V.
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
17.07.2018 | Information Technology
17.07.2018 | Materials Sciences
17.07.2018 | Power and Electrical Engineering