Nutrient budgets of Ontario organic dairy farms

Abstract

. 2008. Nutrient budgets of Ontario organic dairy farms. Can. J. Soil Sci. 88: 107Á114. 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 (B10 mg kg ) 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 aveage 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. Les exce´dents annuels d'e´le´ments nutritifs a`la ferme de 75 (N), de 1 (P) et de 11 (K) kg par hectare annuellement sont infe´rieurs a`ceux rapporte´s dans les e´levages de bovins laitiers en claustration des É .-U., signe que les plus faibles re´percussions des ope´rations hors ferme sur la qualite´de l'eau et de l'air pourraient eˆtre be´ne´fiques pour l'environnement. La concentration moyenne ponde´re´e du P dans le sol e´tait faible ( B10 mg par kg) dans environ la moitie´des exploitations, alors que celle d'ions K e´changeables e´tait de moyenne a`e´leve´e partout (de 76 a`160 mg par kg). Quatre exploitations avaient instaure´une approche d'autosuffisance, la majeure partie des aliments du be´tail e´tant produite sur place avec peu d'achats de P (1,37 a`1,90 kg de P par hectare annuellement), ce qui a eu une incidence ne´gative sur le bilan du P a`la ferme (en moyenne (1,54 kg de P par hectare annuellement). Une approche inte´gre´e a`la gestion des e´le´ments nutritifs assortie d'une strate´gie suffisamment souple pour l'achat des aliments du be´tail favorise la durabilite´des e´levages biologiques de bovins laitiers.

Management Practices and Their Potential Influence on Johne’s Disease Transmission on Canadian Organic Dairy Farms—A Conceptual Analysis

“…In Ontario, organic farms usually have lower milk production per cow and per hectare than conventional herds [8]. These findings are supported by the earlier Ontario study from Stonehouse et al [9] but not by Ogini et al [10].…”

“…While there are many other reasons why producers convert to organic farming, some smaller farms might see an opportunity to avoid the consolidation process and increase farm income by converting to organic milk production. More recent reports demonstrate that organic farms tend to be smaller than conventional farms [7,8,67,68] (Figure 2). Small farms have been shown to have decreased odds of being JD positive [30,38] and, thus, smaller organic farms might have a reduced JD herd level prevalence compared to larger conventional farms.…”

“…In multiple studies, it was reported that Ontario organic farms have a high proportion (>50%) of their land base utilized for forage production for livestock [7,8,11]. Farm nutrient (N, P, K) surpluses per hectare per year were lower than reported on conventional farms, and soil P levels were low on approximately half of the farms whereas exchangeable K levels were moderate to high on all farms.…”

“…Farm nutrient (N, P, K) surpluses per hectare per year were lower than reported on conventional farms, and soil P levels were low on approximately half of the farms whereas exchangeable K levels were moderate to high on all farms. Some organic farms showed a negative P balance, which indicates that depletion of soils could happen if insufficient nutrient supplementation is done [8].…”

“…Milk yield on organic farms is usually lower and the herd size is comparable or smaller than on conventional farms [7][8][9]. An indicator for milk quality is the number of white blood cells in the milk, commonly referred to as somatic cell count or SCC, with low SCC indicating good milk quality.…”