Knowledge on crop rooting systems provides essential physiological information for the development of appropriate crop rotation systems to improve soil water and nutrient use efficiency, increase crop yields, and optimize the productivity of the whole farming systems. Crop roots are the main organ that is responsible for the crop plants to develop drought and lodging resistance and the ability to tolerate root diseases (Gan et al. 2007). In addition, crop roots account for a large part of net input of crop biomass into soil organic carbon (C) pools.  Knowing the C derived from crop roots is critical for the determination of C sequestration, C budget and C dynamics in the soil.  An increase in root growth will lead to a larger input of organic C to soil due to increased rhizodeposition and root litter.  In typical dryland cropping systems in western Canada, multiple types of crops, namely cereals, pulses, and oilseeds, are being grown in a sequence (Miller et al. 2003). The development of the best crop sequences must consider crop rooting systems, so that cereals, legumes, oilseeds, and other alternative crop species can be arranged in an appropriate order in a rotation system (Gan et al. 2003). Fields with different preceding crops may have been conditioned with different levels of root biomass, decomposition of root materials into soil nutrient pools and conserved soil moisture and other residual elements in the different rooting depths.