Posts Tagged: steam

Weed-killing robots and steam beat weeds, pests

AI-trained machines slash labor costs Experimental robots are reducing the costs of hand-weeding by learning the difference between weeds and lettuce. In addition, steam can clear the soil of fungi and spores that cause lettuce and spinach to wilt, reducing the need for chemical herbicides in...

More on steaming

From the weekly newspaper for California Agriculture, Ag Alert • Dec. 2, 2020 • California Farm Bureau Federation   Advisors seek practical use of steam in weed control By Bob Johnson Steam-treating a shallow band of soil within the seed line before planting may offer, when...

Evaluation of banded steam for weed and disease control in lettuce

Despite the tremendous need, there are currently no preemergence herbicides that are organic-compliant. Steam injected into the soil such that the soil temperatures reach >140°F for 15-20 minutes will kill weed seed in the soil. The effect of this reduction in the seedbank viability results...

UC specialist looks into steam cleaning soil

UC researchers are considering the use of hot steam fumigation on coastal central California farms to prepare soil for planting strawberries and new orchards and vineyards. Farmers there have for years relied on methyl bromide, but the phase-out of the powerful soil fumigant is closing in, according to an article in The Packer.

To study the steam method, UC weed specialist Steve Fennimore outfitted a tractor with a boiler that heats steam to more than 300 degrees F. Ten-inch spikes inject steam into the ground.

The article, written by Elizabeth Ashby, said sandy or light soils are the easiest to treat, but Fennimore has had success in clay loam in Watsonville, Calif.

“This machine…there is something special about it,” Fennimore was quoted in the story. “It is surprising how fast it heats the soil. Within two minutes, it will take 60-degree soil and heat it to 200 degrees. It is like a microwave.”

The quick-acting treatment allows growers to steam in the morning and plant that afternoon when the ground has cooled. That stands in contrast to soil solarization, another possible methyl bromide alternative. Under the solarization system, the field is covered with plastic and the sun heats the soil and kills pathogens. Solarization takes six weeks.

One drawback of the steam system, however, is cost. Fennimore calculated that operating the steam machine, labor and fuel run $4,200 per acre. Methyl bromide in California costs $2,700 to $3,000 per acre. Applying steam to raised beds rather than entire fields could cut expenses to about $3,000 per acre.

Future studies will examine less expensive fuels like propane, ways to speed up the steam injection process and spot treatments.

UC specialist Steve Fennimore is studying steam soil treatment.

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