MEDIA & FERTILIZER
Harvesting Peat from the Bog to your Operation
Figure 1. A virgin sphagnum bog in Quebec, Canada. Learn what’s involved in harvesting, packaging and shipping peat for horticulture production. The Canadian Peat Moss Industry
By Neil Mattson, Bill Miller and Jeff Bishop • In 1999, 1.2 million metric tons of peat (10 million cubic meters) was harvested in Canada. n the 1960s, professors at Cornell University Harvesting and Processing were among the fi rst to advocate the use of peat When a company wants to open a new peat • It is estimated that 70 million metric tons in their soilless Peat-Lite mixes for greenhouse bog for harvesting, surveys are conducted to of peat accumulates annually in Canada, so production. Several properties of peat moss determine if a site contains horticulture grade current harvesting represents 1.7 percent Ihave led to its widespread adoption by the industry sphagnum. Th e peat should have a depth of at of annual accumulation. Thus, peat is over the intervening decades; these include: high least 2 meters, as it is desirable that a bog be able accumulating some 60 times faster than water holding and cation exchange capacity, lack to be harvested for many years (Figure 2). Ditches it is being harvested. of residual herbicides and weed seeds compared are built to drain surface water and access roads • Canada is estimated to contain 280 mil- to soil and composts, and low incidence of root- lion acres of peat land. In contrast, the peat borne pathogens. industry harvests on ca. 42,000 acres. Recently peat has received attention in terms • Canada produces about 8 percent of the of its place in sustainable plant production. While global peat annually. many other organic-based components such as coconut coir, rice hulls and compost are available • Around the world, by far the major use of for soil-less substrates, peat remains the number peat is for fuel (home heating). Canada’s peat one component (by volume) in U.S. greenhouse industry is 100 percent for horticultural use. potting mixes. We recently had an opportunity to visit peat bogs in Quebec, Canada, where several Source: Daigle, J.-Y. and H. Gautreau-Daigle. companies harvest sphagnum peat (Figure 1). We 2001. Peat Harvesting and the Environment. wanted to learn how peat is harvested and pack- 2nd Ed. Issues paper No.2001-1. Published in aged, why these processes are followed, and how Figure 2. Th e drainage ditch (foreground) reveals, partnership with the North American Wetlands they impact the product you receive. how thick the layers of peat are in this particular bog. Conservation Council Committee.
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Figure 3. A large “ four-headed” vacuum harvester. Figure 4. Th e contents of a vacuum harvester are emptied.
are built to allow heavy equipment fi elds very carefully using vacuum to operate. harvesters, which collect fi bers from Harvest takes place when bogs about a ¼ -inch top layer (Figure are not frozen, usually May through 3). Th e use of vacuum harvesters September. Milling machines are reduces physical disturbance to the used to loosen only the top inch or peat. Th e goal during the entire har- two of peat; this keeps the under- vesting and processing process is to lying bog intact so it is not able to preserve the integrity of peat fi bers. erode away. Mechanical damage can break apart Th e top layer is allowed to dry in sphagnum fi bers, which decreases the sun for a few days. Abnormally its porosity in a container and can rainy conditions delay the ability to create more dust. Several passes can harvest from a given site. Contrary be made over the same fi eld during to what some believe, peat is no the year. In total, about a 2- to longer cut into large bricks for har- 3-inch layer of peat may be mined Figure 5. Peat is loaded onto a conveyer line for screening. vest. Instead, peat is collected from for a site in one year. A given peat
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bog is harvested for many years. For cation exchange capacity (improved diff er based on the sphagnum spe- texture that aff ects drainage, cation example, we viewed a peat bog that nutrient retention) and better dis- cies growing in the bog as well as the exchange capacity, and microbe has been harvested continuously ease suppressive properties. depth of the peat layers being har- fauna, which can sometimes off er since 1929. Peat and peat-based potting vested. Substrate suppliers often sell disease suppressive properties. mixes are either packaged loose or peat from several locations intended Very little material from a peat Processing and compressed. Loose peat is easier for diff erent purposes. Properties bog is wasted. Th e top layer of Packaging to use directly in a pot, but is less that can diff er include: fi ber length/ sphagnum (un-decomposed) is sold Vacuum harvesters empty their effi cient to ship. Compressed bales peat into large piles at the edge of the allow the same amount of peat to be bog (Figure 4). Large truck-drawn packaged in a smaller volume, which hoppers carry the vacuum-harvested helps reduce shipping costs. While peat to the nearby processing facili- compressed bales are sold based on ties. Th e collected peat is screened to the volume in the bag, once the remove impurities such as wood, roots peat is fl uff ed and used, it will typi- or large clumps of peat (Figure 5). cally yield two to three times that Depending on the peat’s purpose, it volume. At the facility we were vis- is then packaged “as is” or it is blended iting, quality control personnel were with other materials to create soil-less checking 3.8 cubic foot compressed potting mixes. Several components bales to ensure that once they were are added to peat to develop potting fl uff ed they yielded at least 9 cubic mixes. Wetting agents are added as feet of peat moss. dry peat repels water and is hard to Increasingly, greenhouse opera- moisten initially. Limestone is added tions are purchasing large pallet- to raise the pH of peat to about 6.0, sized peat bales. Th e large bale is which is perfect for root growth and loaded into a bale buster, which nutrient availability. Aggregates such fl uff s the peat as it shaves down the as perlite or vermiculite are added to bale. Th ese large bales are benefi cial Take a close look increase air porosity. as they reduce the labor associated Finally, a starter nutrient charge with opening many small plastic may be added for initial plant bales. Th e large bales also provide at PBH. growth. Peat from diff erent sources signifi cant savings of plastic. may be combined together at this stage — for example, the upper Lessons from the Bog layers of bogs often yield fl uff y fi bers In the end, the trip to several peat Discover the best rice hulls with very good air porosity, while bogs and packing facilities led to in the business. older layers may yield more highly some insights. decomposed peat which has a greater Not all peat is the same. Locations • Improved processing verifi es cleanliness, consistency • Independently tested for purity • University researched, greenhouse proven • Optimum porosity, drainage Plug Dislodger • Non-dusty material • Naturally renewable resource • Lower basic cost than perlite
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for specialty horticulture uses, such in the container. Th ese layers may consumer garden products, and is into aggregate free mixes. Even the as lining hanging baskets or in orchid be used in aggregate free mixes or also ideal for use by the mushroom wood materials screened out before mixes. Th e next layers contain higher in mixes with a lower percentage industry. Clumps of peat, selected processing can be composted. quality and less decomposed peat of perlite. Finer grade peat material out in the screening process, can be Following the productive life of fi bers that allow for better drainage is used in our propagation mixes, used for animal bedding or added a given bog, Canadian law requires harvested peat lands be returned to sphagnum bog, reclaimed as wildlife or forest land, or turned into land for agricultural production – typically acid-loving plants such as blueber- ries or cranberries (Figure 6). g
Neil Mattson is an assistant pro- fessor in the Department of Hor- Commercial Greenhouses ticulture at Cornell University, Bill Miller is a professor in the Depart- ment of Horticulture at Cornell University and Jeff Bishop is with Lambert Peat Moss. Mattson can be reached at [email protected].
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To see our full line of retail and commercial greenhouses, visit us on the web at www.poly-tex.com or call us toll-free at 800-852-3443. Figure 6. A sphagnum bog ©2008 Poly-Tex, Inc. All rights reserved. successfully established into a Lowbush blueberry fi eld. Write in 118
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