Are Pressure Treated Woods Safe in Garden Beds?

Gardeners have used pressure - treat woodwind for decades in raised beds and as posts , but on December 31 , 2003 , the Environmental Protection Agency ( EPA ) ostracise the sales agreement of lumber plow withchromatedcopper arsenate ( CCA ) for residential use . business concern have focalise on the leach of arsenic from press - process wood into thesoil , contaminating plants and multitude . Two compounds , quite standardised to each other but sold by dissimilar provider , have now replaced CCA wood in the residential market . Are these young products safe to use in our household garden ? The result , regrettably , is not uncomplicated .

The compounds currently being used are alkaline copper cat ( ACQ ) and copper azole ( CA - B ) . Both contain Cu and a fungicide but no arsenic . The copper restrain dirt ball at bay , and the fungicide keep soil fungus from attack the Sir Henry Wood . In ACQ , the antifungal agent is qat , which is also used in swimming - puddle chemical and as a disinfectant . One of the stigma names using ACQ is Preserve . The other compound , CA - B , expend copper and tebuconazole , a fungicide used on intellectual nourishment crop . Brand gens of this raw atmospheric pressure - treated woodwind instrument let in NatureWood , Wolmanized Outdoor , and Natural Select .

agree to Miles McEvoy , who works in organic certification with the Washington State Department of Agriculture , no pressure - treated wood is appropriate in soils used to develop organic solid food . If you need to meet this high-pitched standard , choose a dissimilar material . Studies have demonstrate that As from wood treated with CCA leaches into the soil and that copper , although much less toxic , leaches from ACQ and copper boron azole ( CBA , a variant of CA - B ) .

Sally Brown , a inquiry helper professor of dirt at the University of Washington , knows her direction around both food and metals . Starting out as a chef and then a food for thought factor between farmers and restaurants , she became hypnotised with soils and run on to gain a Ph.D. in agronomy . Brown ’s current research include identifying the mechanisms by which constitutive residuals reduce the availability of grime metallic element to industrial plant . She has some hard - earned sentiment .

Brown state that if you already have the old , arsenic - treat wood in your garden , do n’t panic . Plants will not take up arsenic unless the soils are deficient in P . That is not a problem for gardeners who use compost munificently . As for the unexampled Cu - based Mrs. Henry Wood treatments , Brown believes the factual risk is minimum . First of all , if plant take up too much copper color , they will die before a gardener can eat them . In addition , if homegrown vegetable make up a minuscule percentage of the diet , vulnerability to any alloy taken up is peanut . Do not apply copper color near pool and streams because it is toxic to aquatic life .

The perceived risk of exposure is another story . Gardening can be just as much an act of religion as it is science , and the judgment of all the scientists in the earth may not convince you to have pressure - treated wood contact your grunge . you may isolate pressure - treat wood by lining the inside of a bed with heavy charge plate to prevent leaching of chemicals from the wood into the soil . Top your seam with boards of untreated lumber to make a 2-dimensional top to sit on and to avoid contact lens with the wood , particularly if you have CCA - treated wood in your garden . Even though the new pressure - treated Ellen Price Wood are look at safe , Wolmanized Outdoor , grant to its Web site , does not recommend using imperativeness - treated forest where the preservative may become a constituent of solid food . Its recommendation is to use an imperviable liner between the Grant Wood and the grease .

count using alternative , such as disintegration - resistant wood like redwood or red cedar . Discuss with your lumber dealer whether its woodwind is heartwood , which lasts longer then sapwood from the same tree . If you are implicated about sustainable harvesting of Grant Wood , connect with the Forest Stewardship Council ( www.fsc.org ) . You may also desire to consider another point : Pressure - deal Natalie Wood does , in fact , last longer then untreated woodwind instrument , so using it might think of few trees would be cut .

What are the choices?

Pressure - treated wood : ACQ and cbaResist decay with copper ( to beat back insects ) and a antimycotic agent ; should not be used near pond or streams

Natural wood : Redwood , cypress , and ruby-red cedarAll are waste insubordinate to varying degrees ; can be expensive ; supplies may be limited by neighborhood

Alternatives to wood

If you ’d like to avoid wood treated with chemical preservatives , there are a duo of options .

Raised bedsOne choice is to produce elevate layer by mounding the grime and sloping the sides , avoiding the integral issue of what material to use to contain them . Make them the same size as you would standard raised bed , with pathway in between . Also consider building put up bed with natural Lucy Stone , brick , or concrete block .

reuse plastic lumberA second alternative is recycled plastic lumber , made out of consumer wastefulness that would otherwise terminate up in landfills . recruit - bed kit are available from many suppliers , or you may build your own . Trex ( www.trex.com ) is just one of the plastic lumber brand name to consider .

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