Information is presented showing that the problem of assessing the relative moisture efficiency of crop rotations under study on District Experiment Substations located on soils varying in texture, can be successfully studied by the application of statistical methods. The results of this study show that the mixed-farming crop rotations of four and eight years duration in which grass and legume crops are included in the cropping system, are significantly more efficient in the utilization of soil moisture; tend to produce higher average crop yields; more efficiently conserve plant nutrients, and are more adaptable to a permanent agricultural economy in south-western Manitoba than are the two and three-year grain rotations.