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Can I use pressure-treated lumber if I’m transitioning to organic?

Answer: Lumber treated with prohibited materials is not allowed under the USDA National Organic Program (NOP) Regulations. The NOP prohibits most, but not all, synthetics. Lumber is pressure treated to resist insects and fungi, but the materials used are toxic to humans. For posts and lumber that are in contact with soil, crops, or livestock, the options include untreated lumber, alternatively treated lumber, alternative plywood products, and untreated fence posts. Producers will need to consult with their organic certifiers to determine whether an alternative product is allowed. See a list of accredited certifying agents here. Pressure treated wood is specifically addressed in Section 205.206(f) of the NOP Regulations, which declares that “a producer must not use lumber treated with arsenate or other prohibited materials for new installations or replacement purposes in contact with soil or livestock.” This restriction addresses a number of applications, including the following: ? Lumber used to build a pasture farrowing hut for hogs, a cattle feed bunk, or a shelter for sheep or calves.? Lumber for floors, ceilings, or walls of feed or crop storage areas.? Fence posts in livestock pastures and holding or confining areas.? Posts, plant stakes, trellising, hoophouse baseboards, and frames of planting beds used in fruit and vegetable production.Treated lumber that is isolated from organic production?such as wooden building materials that are not in direct contact with either livestock or crops?might not be prohibited but rather might be restricted in its applications. The NOP Production and Handling Preamble, Subpart C (7) addresses this issue as follows:”This provision prohibits the use of lumber treated with arsenate or other prohibited materials for new installations or replacement purposes in contact with an organic production site. We included this modification to clarify that the prohibition applies to lumber used in direct contact with organically produced and handled crops and livestock and does not include uses, such as lumber for fence posts or building materials, that are isolated from production.”The National List of Allowed and Prohibited Materials for organic production may be foundin Sections ?205.601 and ?205.602 of the NOP Regulations.Producers should check with their certifiers to see whether treated wood may be used for noncontact areas. Remember, it is important to document any production-isolated uses of treated lumber on the operation’s Organic System Plan.For more information, consult the ATTRA publication Pressure-Treated Wood: Organic and Natural Alternatives. This publication provides information on alternative products, especially for certified organic farming operations, and also includes products that may be of interest to home gardeners but are not approved for organic production.