Soil Test Phosphorus and Nutrient Budgets for 15 Organic Dairy Farms in Ontario

C. Roberts¹, D. Lynch² and P. Voroney¹

While the technical and economic aspects of the Ontario organic dairy industry have been well characterized, the nutrient status and nutrient use efficiency of these production systems is less well understood. In 2003, the project commenced collecting data to characterize farm and soil nutrient status, on fifteen long term (>10y) organic dairy farms in Ontario. Surface (0-15cm) soil sampling of all 225 farm fields was completed during the period Oct. 2003 to Apr. 2004. Soil test (0 .5M NaHCO3) P levels were found to be low to very low (<10ppm) on over 60% of farm fields tested. Within organic farms, low soil bicarbonate Pi levels appear to occur across all management systems, with only a weak relationship (R2 = 0.36) between farm stocking rate (nutrient intensity) and soil test P. All managed nutrient imports and exports have been recorded and annual mass nutrient (N, P, K) balances are being determined for each farm and will provide insights as to the trends in nutrient status on these farms, and will allow for an assessment of whole farm nutrient use efficiency.

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Source
2nd OACC Organic Research Workshop, Presented in association with the Organic Connections: Prairie Wide Organic Conference and Trade Show, November 14-16th, 2004


Author Locations and Affiliations
(1) Department of Land Resource Science, University of Guelph
(2) Organic Agriculture Centre of Canada, Nova Scotia Agricultural College
* Correspondence: robertsc@uoguelph.ca


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