WHEAT YIELDS AND SOIL AGGREGATION AFTER PERENNIAL GRASSES IN A SEMI-ARID ENVIRONMENT

Spring wheat grown the year following breaking of stands of crested wheatgrass (Agropyron cristatum L.) or bromegrass (Bromus inermis Leyss) in a semi-arid region of the Canadian prairies yielded 17 per cent less than wheat grown on summerfallow in a 2-year wheat-summerfallow rotation. After three successive cycles of the 2-year wheat-summerfallow rotation on the sod breaking, the wheat yields were about equal to those obtained from the check plots. The grasses did not improve soil aggregation any more quickly than that which occurred in the wheat-fallow regime under an adopted strip cropping management.