Oliver Moore: Many methods for machine weeding

Padraig Fahy of Beechlawn organic farm in Galway.

There are a number of mechanical ways to weed. Flame weeding may surprise some as permitted in organic, due to the fossil fuel use. 

However the soil and biodiversity impact of flame weeding is far lower than that of herbicide application.

There are backpacks available for hand flame weeding. 

This is often used in smaller sets ups, or for specific crops and areas. 

These are used just before the crop comes up.

Padraig Fahy of Beechlawn organic farm in Galway uses six techniques on his farm.

“We use a flame weeder,” he says. 

“First you prepare a stale seed bed, after 7-10 days you burn the weeds off. Weed seeds come up before the carrots or beetroot — there is a window there that you have to catch. 

"This year the beetroot was up so early that we missed it and had to use the brush weeder. 

"The flame weeder is important for direct seed sowing, as with carrots, spinach, swede and parsnips.”

Flame weeding sets the weeds back about two weeks. The flame is about 9in from the ground.

Dedicated flame weeders, ideally with covered hoods, cost between €3,000 and €6,000.

Padraig Fahy also uses a cage weeder. This is also a one-person operation. 

The Kress and Co cage weeder “involves two weeding cages in a row, which rotate in an adjustable depth of 1cm-4 cm in driving direction between the plant rows. 

"The cage in front activates the rear one and is loosening hard soil. The second cage crumbles the soil and separates soil and weed” — according to the company.

Fahy uses his cage weeder in between plants at four to six weeks.

The brush weeder is for all crops up to three to four weeks. The Fobro brush weeder that Padraig Fahy uses is a six-year-old Swiss machine. 

He uses this for leeks and brassicas, but especially for root crops. These cost about €15,000 and have an Irish agent.

Another machine on his east Ballinasloe farm is the Einboeck Hillstar weeder. This is especially good for ridges or drills, so is used for potatoes, carrot, leeks and so on. 

Another one-person operation, this is “great for the first two weeks, but no use in the wet”, he tells me.

There are another two types of weeder on this single farm. The first of these falls more into the category of typical cultivator/harrow.

Beechlawn use the Tripple K Springtine harrow (about €275 plus vat), which they use for weeding the paths.

Finally, there is also flat bed weeder. This flat bed actually carries people on the back who hand weed while lying down. 

This is far more efficient than the “footing turf” approach to weeding, where you stand, crouch, pick, and move on until your back aches too much.

Their version was made on the farm itself. It is driven by a tractor with creeper gears. 

The tractor drives very slowly — about 3km per hour — and people lie flat on the device, face down handweeding the weeds they see. 

“This year, with the weather, what we missed we’ll catch with the flatbed,” Fahy says.

Interestingly there are now tractor-free, driverless, solar powered versions of this developed, for anything from one to up to nine weeders. Some of these use tracks rather than wheels to avoid compaction. 

The WundaWeeder (which also makes planting, thinning, transplanting, harvesting and other manual acts easier) is one, and it’s for one person only.

However, models exist for carrying up to nine, without a tractor, solar powered.

There are indeed many more. 

Organic research organisation FiBL have a very informative 20-minute video on mechanical weeding, in commercial vegetable production. 

Products demonstrated include star cultivator, ridge cultivator, flex tine harrow, torsion weeder, finger weeder, computer-controlled cultivator, camera-controlled goosefoot cultivator, brush hoe, duo-parallelogram, bed-disc weeder, multi-row rototiller, and subsurface cultivator.

For further information, key “Mechanical Weed Control FiBL” into YouTube.


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