Each of these factors in growing healthy and safe vegetables incorporates the safety of pressure-treated wood in vegetable gardens. This refers to the type of pressure-treated wood one can use in copper, boron, and creosote treatments. Individuals who have dealt with gardeners will be better equipped in making a decision to use the material with minimized risks.
Understanding Pressure-Treated Wood
Pressure-treated wood resists decay and insects and can be quite prevalent in outdoor structures. While it is treated with chemicals that make it durable, these same chemicals often raise safety concerns, especially in regard to vegetable gardens. It is generally advised that vegetables stay away from any pressure-treated wood to avoid the possible leaching into the soil of hazardous substances (How Wood Is Pressure Treated, n.d.).
Pressure-treated wood can be identified by various markings or by knowing what to look for in treated lumber. Most pressure-treated lumber has a green or brown tint to identify it as treated with preservative chemicals.
Arsenic-Treated Wood
One of the most debated treatments involves arsenic-treated wood, which is considered unsafe for use in immediate contact with food and water supplies. The U.S. EPA reviewed studies pertaining to the risks associated with arsenic-treated wood used in raised vegetable gardens and came to a general conclusion that the use of this type of wood presents a potential risk (Arsenic-Treated Wood | NCHH, n.d.).
While the research done by the Department of Agriculture in South Africa showed there may be some very minor additional leaching with respect to root vegetables, the FDA nonetheless advised against the use of arsenic-treated wood near food crops. Finally, the EPA did subsequently raise vegetable beds made from arsenic-treated wood as a restricted-risk product.
Those gardeners who are concerned with the safety of using the arsenic-treated lumber, they have other options to consider. One of the ideal options includes heat-treated wood for those who want to construct raised beds. Any type of pressure-treated lumber needs one to employ the use of protection such as gloves and even goggles in order to eliminate exposure to any toxic chemicals that could be present.
Copper-Treated Wood
Copper-treated wood is considered fairly harmless, especially ACQ, to use in vegetable gardens. This does have some risk of copper leaching into the soil; studies however indicate it takes place at such minimal levels it is not likely to harm the plants. As a fact, toxic levels generally would kill the plants prior to their being able to be harvested (Denny, 2023).
Those gardeners who will be using copper treated wood should beware of the edges. This newer variety of pressure-treated lumber is claimed to be comparatively innocuous if used inside of a vegetable garden. In fact, the concept of metal leaching actually goes further by lining the insides of these raised beds with plastic. Besides, keeping the soil pH at about 6.5 may further minimize risks of copper leaching into the aquifers. If safety is a concern, the removal of roots from the soil during harvest in root crops could further mitigate potential risks.
Creosote-Treated Wood
The use of creosote-treated wood, such as in railroad ties, in vegetable gardens is controversial. While some information is available suggesting that railroad tie usage does not significantly pose a health hazard, several safer alternatives do exist including plastic lumber, concrete blocks, bricks and wooden barrels.
Though quite effective as a wood preservative, it has lingering effects on vegetable gardens. Newly treated wood with creosote keeps fumes hanging in the air for many years to keep releasing toxic elements in the air up to nine years from the treatment. On the contrary, using untreated wood is quite risky too because it might invite termites and other insects.
Conclusion: Pressure-treated wood can be used for vegetable gardening but needs extreme caution. Knowledge of the type of treatments and associated risks in each will help a gardener make right choices that not only protect his health but also the life of his garden. Employ protection where needed, and alternative materials when possible, in your establishment of the garden space.
References
Arsenic-Treated Wood | NCHH. (n.d.). Nchh.org. https://nchh.org/information-and-evidence/learn-about-healthy-housing/health-hazards-prevention-and-solutions/arsenic-treated-wood/
Denny, C. (2023, May 9). 8 Different Types of Treated Wood and Their Applications. American Pole & Timber; American Pole & Timber. https://www.americanpoleandtimber.com/8-different-types-of-treated-wood-and-their-applications/
How Wood is Pressure Treated. (n.d.). Treated Wood. https://www.treatedwood.com/learn/how-wood-is-treated
