Approximately 4800 cattle feedlots currently operate in Alberta, Canada. The large amount of manure produced annually creates disposal problems for feedlot operators. The objective of the present study was to evaluate the effects of long‐term annual manure application on barley (Hordeum vulgare L.) performance grown on clay loam soil (Dark Brown Chernozemic, Typic Haploboroll) near Lethbridge, AB. Feedlot cattle manure was applied annually from 1973 to 1989 to irrigated plots at 0, 60, 120, and 180 Mg ha−1 (wet wt. basis) and to nonirrigated plots at 0, 30, 60, and 90 Mg ha−1. Manure was incorporated with a cultivator plus disk, rototiller, or plow. Method of incorporation did not affect barley yields, but timeliness and amount of precipitation in the current and previous year were important in determining barley response to manure treatments. When moisture conditions were below normal, manure at any rate of application had a negative effect on yield of nonirrigated barley. Under nonirrigated conditions, average barley yield was depressed by 10 and 16% for the 60 and 90 Mg ha−1 manure rates, respectively. Barley yield increased when manure was applied under irrigation, with the 60 Mg ha−1 rate producing a 20% higher average yield than the control. Although manure was disposed of annually on the soil at up to three times the recommended rate without reducing barley yields below those of the unmanured plots under irrigated conditions, such practice is not recommended because of potential soil and water pollution.