Electric weeding
Weed control using an electric current
Thématiques
Strictly speaking, electric weed-killing consists of passing apowerful electric current (with a power of 3,000 Watts, voltage of 4-7,000 V, or intensity of 0.5-2 A, depending on the resistance of the plant and the soil) directly over the plants to be controlled, right down to the roots, via an electrode touching the aerial part of the plant. The weeds are eradicated, both the aerial parts and the underground parts.
Presentation
Characterisation of the technique
Unlike manual or mechanised hoeing, this technique does not cause the soil to move. This avoidserosion and disruption of the soil structure, as well as encouraging seed dormancy. As the killed plants remain in place, the soil surface remains shaded and new seeds will not find a seedbed conducive to germination. As a result, weedregrowth is delayed.
Main points :
- A new alternative weed control technique
- Electro-physical destruction of weeds or cover crops
- Mode of action based on a closed, uniform and targeted electrical circuit
- Root action: treats the plant from the leaves down to the roots in the soil
- Great importance attached to the safety of users and wildlife
It should not be confused with electrical thermal weeding, which consists of creating a thermal shock using air heated to 650°C by a resistor subjected to an electrical current, although the principle is the same, drying out the weed cells and causing them to burst.
For purely electrical weed control, a second electrode is placed at ground level to recover the current and close the electrical circuit.
Electric weed control depends on a number of parameters. There are those linked to :
- the plants to be eliminated (species, size, age, density, root system, etc.)
- the environment (soil moisture and resistivity, climatic conditions, etc.)
- the machine (electrodes used, power, speed of movement, contact time, etc.).
Example of implementation :
Semi-industrial tests have been carried out in Brazil in agriculture (coffee, soya, maize, grass, oats and wheat) and in non-agricultural areas, using a model developed by the Brazilian ex-Sayyou, now Zasso Brazil, a subsidiary of Zasso Group AG, the Swiss-German parent company. The CRA of French Guiana and the DRAAF took part in an on-site presentation in 2015 : a video was shot and can be viewed on the Ecophytopic channel on Youtube. Since 2017, Zasso Group has been adapting and developing tailored solutions for the Local Authorities, Green Spaces and Agriculture/Viticulture segments. Its target markets in Europe are France, Germany, Switzerland and the Benelux countries.
In France, the first quantitative impact tests and demonstrations took place in 2018, notably in May 2018 during the Journées Terres Innovation - Agriculture et Viticulture organised by the Marne Chamber of Agriculture and Acolyance, in July by the Institut de la Vigne et du Vin, and in mid-September 2018 with ARVALIS and an Agro Club led by Vincent Vaccari of Dijon Céréales.
Technical details :
Zasso's XPOWER consists of a generator and two rows of applicators operating as two poles. It is based on a closed circuit that travels from a first row of applicators to the undesirable plants, before returning to a second row. The electric current passes through the leaves and stems to the roots, bursting the vessels in the plants and drying them out in a matter of minutes. The system has a stable, uniform power supply.
What's more, the Electroherb effect is independent of climate and season, since the electrical current does not need to be flowing through the sap to be distributed. The flow of current through the plant takes effect immediately, rapidly damaging the vascular bundles, right down to the roots, without having to heat the whole plant. Contact times of between 0.01s and 1s are sufficient, depending on the size of the plant. Larger plants are by definition in contact for longer.
In terms of power, in most cases a generator is connected directly to the drive shaft of a tractor or similar carrier. In the case of very large systems or insufficiently powered vehicles, a separate power generator may be used. Portable equipment is controlled from a socket or small generator.
Zasso's first commercial equipment in 2019 will be used for potato stubble removal and cover crop destruction (inter-cropping), i.e. full weed control. Inter-row applicators for maize/soya, as well as intercep for vineyards/arboriculture, are currently being developed.
In order to optimise treatment parameters, including working speed, time and power output, AGXTEND, the Case New Holland equipment manufacturer's platform, will provide an application service to help XPOWER users in its application.
Application of the technology to...
Applicationperiod : During intercropping, on established crops. Depending on the season, the plant species and the size of the plant, a treatment once every 1 to 4 months during the growing season may be necessary.
Spatial scale of implementation : Plot / Farm.
All crops : Generalisation can be tricky.
Plants with a high water content and/or few stems and roots in relation to their leaf mass require little energy and are relatively easier to treat. On the other hand, tall, dense or woody grasses require more energy and special applicators.
All types of soil : Generalisation can be tricky.
The soil can be a factor to be taken into account when setting the parameters of the machine: in particular, its humidity and resistivity can influence the power of the electric discharge experienced by the plants to be eliminated.
Zasso's XPOWER has relatively fewer humidity constraints than chemical herbicides. For the electricity to have an impact on the plants instead of dissipating on the surface, the plants must not be full of water. Wet soil is not in itself a problem as long as the tractor can move without damaging the soil. The "Electroherb" method does not encourage germination, as it neither stirs nor warms the soil. Plants with larger rootstocks or rhizomes are severely weakened, but may require more than one treatment.
All climatic conditions : Easily generalised, no particular contraindications.
Effects on the sustainability of the cropping system
Environmental" criteria
Tests on the environment (in particular on biodiversity and the preservation of animals living in the soil) are being carried out by ARVALIS and INRA, among others.
The tests carried out in 2017 showed that, under realistic conditions of dosage and method of treatment with XPOWER in arable crops, the trials did not show any significant effects on earthworms, horsetails, oribatid mites and micro-organisms : the systemic effect of XPOWER right down to the roots makes soil movement superfluous and leaves no residue, thus protecting its ecosystem.
Agronomic" criteria
- No soil movement
- Minimised erosion
- Maximised soil conservation
- No unnecessary heating
- No chemical residues
To find out more
- Agricultures sans herbicides - Joseph Pousset France Agricole, Book, 2003 Joseph Pousset is an organic farmer from Normandy(Department of Orne).
- Electroherb de Zasso - Zasso https://zasso.eu/en/technologies-digital-weeding/, Website Contact : info@zasso.fr
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