Publication Date:
2008-02-01
Description:
The sustainability of organic dairying in Canada, with respect to nutrients, remains unexamined. To assess how management affects nutrient status, we documented whole farm nutrient (NPK) budgets over 2 yr (2003 to 2005) and soil (0 to 15 cm) P and K status on 15 long-term Ontario organic dairy farms. Farm size, livestock density and herd productivity averaged 110 ha, 1.00 livestock units ha-1 and 5656 kg milk cow-1 yr-1, respectively. Annual farm nutrient surpluses of 75 (N), 1 (P) and 11 (K) kg ha-1 yr-1 were lower than those reported for confinement-based dairy farms in the United States, pointing to possible environmental benefits from reduced off farm impacts on air and water quality. Weighted average soil test P levels were low (〈 10 mg kg-1) on approximately 50% of farms, while exchangeable K levels were moderate to high (76 to 160 mg kg-1) on all farms. Four farms adopting a "self-sufficient" approach, producing most feed on-farm, imported little P as feed (1.37 to 1.90 kg P ha-1 yr-1) and had negative average farm P balances (avg. -1.54 kg P ha-1 yr-1). An integrated nutrient management approach, along with a flexible feed import strategy, fosters the sustainability of organic dairying systems. Key words: Organic dairying, nutrient budget, nitrogen, potassium, phosphorus, soil fertility
Print ISSN:
0008-4271
Electronic ISSN:
1918-1841
Topics:
Geosciences
,
Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
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