Turn Up the Heat! An overview of soil steaming and why farmers are making the switch

Picture it: you’re driving through Lancaster’s peaceful farmland, when you spot a farmer driving a tractor in the field. You think nothing of it, until you notice steam pouring out of the tractor as it runs.
What’s happening here?
Soil steaming, also known as field steaming, is an agricultural heat treatment that suppresses weeds, pathogens, and pests. First invented in 1888, agricultural steamers included rakes, tractor-drawn blades, and more. However, with the rise of pesticides in the 1950’s, soil steaming slowly faded out in the States. As organic farming gains popularity, more and more farmers are returning to the practice.
Like boiling water for consumption, field steaming kills pathogens and insects by heating the soil to sterilization temperatures, typically around 180 degrees Fahrenheit. Depending on the equipment and methodology, a single steam can last up to five years, reducing manual labor.
There are three main types of soil steaming: subsurface, mobile, and surface.
- Subsurface Steaming: To implement subsurface steaming, farmers pump steam into the soil by inserting pipes or hoses below the surface. Due to its low portability, this method is most commonly used in smaller, more permanent settings like greenhouses.
- Mobile Steaming: Unlike subsurface, mobile steaming utilizes a self-propelled generator that moves over the soil’s surface. This method is designed to treat large areas quickly and best suits farmers treating open fields.
- Surface Steaming: Farmers lay pipes and hoses over the soil in surface steaming, pumping steam through the mechanism. Then, a “trap” is laid around the perimeter to keep the steam from escaping. Like the subsurface method, this technique is used most often to treat smaller areas of soil, such as in high tunnels, greenhouses, or farmettes.
While soil steaming is certainly a viable option for organic farmers looking to reduce their labor, other factors should be considered.
For example, field steaming kills all microbes in the soil—not just the bad ones. Many crops require “healthy” microbes—such as rhizobia—to grow properly. Farmers who utilize soil steaming often manually reintroduce beneficial microbes by planting inoculated plants or seeds with other crops.
In addition, field steaming tends to consume more time than other sterilization methods, as it takes a long time to provide uniform coverage for large areas of land. This use of time can, in turn, result in delayed planting dates. Plus, steaming equipment is less readily available than other pest control equipment.
As our own Kristin Raab says, agriculture is both an art and a science, and there are no perfect solutions. Regardless of their techniques, our farmers work around the clock to feed the community. As methods change and evolve, we’re proud of our farmers for always working hard and learning new practices! If you would like to learn about other farming techniques and tricks, click here to check out our other blog posts, and take a look at the reference articles below!
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