Plaizier, J. C., Legesse, G., Ominski, K. H. and Flaten, D. 2014. Whole-farm budgets of phosphorus and potassium on dairy farms in Manitoba. Can. J. Anim. Sci. 94: 119-128. Whole-farm budgets of phosphorus (P) and potassium (K) were determined on 10 dairy farms in Manitoba between October 2010 and October 2011. These budgets were determined as the difference between total exports, including milk, animals, feed, and manure, and total imports, including feed, manure, animals, and inorganic fertilizer, for each farm. Farms differed in their feeding and manure management strategies. Two farms imported all their feed and exported all their manure. Other farms produced some of their feed and spread most of their manure on their farm. Whole-farm P and K budgets varied from -0.42 to 3.35 and from -1.31 to 11.27 g kg^-1 milk sold among farms, respectively. Efficiencies of P and K utilization were calculated as the exports as a percentage of imports. The P efficiency averaged 48%, and ranged from 22.1 to 109% among farms. The K efficiency averaged 37%, and ranged from 10 to 98% among farms. In the fall of 2010 and 2011, 94 and 98%, of fields sampled had soil test P concentrations lower than the concentration above which further accumulation of P would be regulated (60 ppm). Of the farms that spread their own manure, the highest P and K efficiency were on a farm that exported a proportion of the produced forages and did not import any inorganic fertilizer. The lowest P and K efficiencies were on a farm that imported concentrate feeds, bedding straw and most forages, and had the smallest land base per milking cow to spread manure. Variations in P and K efficiencies demonstrate opportunities to enhance these efficiencies.