Phosphorus status on Canadian organic farms

R. C. Martin¹, D. H. Lynch¹, B. Frick² and P. van Straaten³

Abstract
In eastern North America, many conventional livestock farms, especially dairy farms with high inputs of feed and fertiliser have excess soil phosphorus levels and an annual phosphorus surplus.

However, a Canadian dairy farm in transition to organic, without fertiliser inputs reduced its farm P surplus to a marginal level. On long-term organic dairy farms in Ontario, most soils tested low to very low in available P as measured by a standard soil test.

Canadian Prairie organic grain farms also consistently demonstrate deficiencies in available soil P. Organic producers have few viable alternatives for P management. Phosphate rock can be acceptable to organic standards (provided they are low in heavy metals, and not processed synthetically), but the P in these becomes available slowly, especially in high pH soils common on most organic farms in Canada.

An alternative is to increase soil P availability. Enhanced microbial activity in organically managed soils may make P more available. Livestock manures are rich sources of available phosphorus, but a majority of organic farmers in Canada do not keep livestock. Off-farm manure sources are subject to organic regulations and hauling costs, both of which may be prohibitive.

Furthermore, manure from conventional farms in Canada may be contaminated by genetically modified material from corn and soybean feed. Additional research is required to improve short-term availability of soil P and long-term replacement.

See a related newspaper article, "Is There Enough Soil Phosphorus on Organic Farms?"

Source
Journal of the Science of Food and Agriculture (2007) 87:2 737–2740

Author Locations and Affiliations
(1) Organic Agriculture Centre of Canada, Nova Scotia Agricultural College, Truro, Nova Scotia, Canada B2N 5E3
(2) Organic Agriculture Centre of Canada, c/o Plant Sciences Department, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
S7N 5A8
(3) Department of Land Resource Science, University of Guelph, Guelph, Ontario, Canada N1G 2W1

en français

Posted September 2008


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Research Extension Courses Consumers -------------------------- Virtual Tours Student & Job Opportunities News Articles Standards -------------------------- Market Information Events Issues Animal Welfare Strategic Plans -------------------------- Links Award-winners Site Map	Phosphorus status on Canadian organic farms R. C. Martin¹, D. H. Lynch¹, B. Frick² and P. van Straaten³ Abstract In eastern North America, many conventional livestock farms, especially dairy farms with high inputs of feed and fertiliser have excess soil phosphorus levels and an annual phosphorus surplus. However, a Canadian dairy farm in transition to organic, without fertiliser inputs reduced its farm P surplus to a marginal level. On long-term organic dairy farms in Ontario, most soils tested low to very low in available P as measured by a standard soil test. Canadian Prairie organic grain farms also consistently demonstrate deficiencies in available soil P. Organic producers have few viable alternatives for P management. Phosphate rock can be acceptable to organic standards (provided they are low in heavy metals, and not processed synthetically), but the P in these becomes available slowly, especially in high pH soils common on most organic farms in Canada. An alternative is to increase soil P availability. Enhanced microbial activity in organically managed soils may make P more available. Livestock manures are rich sources of available phosphorus, but a majority of organic farmers in Canada do not keep livestock. Off-farm manure sources are subject to organic regulations and hauling costs, both of which may be prohibitive. Furthermore, manure from conventional farms in Canada may be contaminated by genetically modified material from corn and soybean feed. Additional research is required to improve short-term availability of soil P and long-term replacement. See a related newspaper article, "Is There Enough Soil Phosphorus on Organic Farms?" *Source* Journal of the Science of Food and Agriculture (2007) 87:2 737–2740 Author Locations and Affiliations (1) Organic Agriculture Centre of Canada, Nova Scotia Agricultural College, Truro, Nova Scotia, Canada B2N 5E3 (2) Organic Agriculture Centre of Canada, c/o Plant Sciences Department, University of Saskatchewan, Saskatoon, Saskatchewan, Canada S7N 5A8 (3) Department of Land Resource Science, University of Guelph, Guelph, Ontario, Canada N1G 2W1 en français Posted September 2008
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Phosphorus status on Canadian organic farms

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