Soil organic C (SOC) has decreased under cultivated wheat (Triticum aestivum)‐fallow (WF) in the central Great Plains. We evaluated the effect of no‐till systems of WF, wheat–corn (Zea Mays)‐fallow (WCF), wheat–corn–millet (Panicum miliaceum)‐fallow, continuous cropping (CC) without monoculture, and perennial grass (G) on SOC and total N (TN) levels after 12 yr at three eastern Colorado locations. Locations have long‐term precipitation averages of 420 mm but increase in potential evapotranspiration (PET) going from north to south. Within each PET location, cropping systems were imposed across a topographic sequence of summit, sideslope, and toeslope. Cropping intensity, slope position, and PET gradient (location) independently impacted SOC and TN to a 5‐cm soil depth. Continuous cropping had 35 and 17% more SOC and TN, respectively, than the WF system. Cropping intensity still impacted SOC and TN when summed to 10 cm with CC > than WF. Soil organic C and TN increased 20% in the CC system compared with WF in the 0‐ to 10‐cm depth. The greatest impact was found in the 0‐ to 2.5‐cm layer, and decreased with depth. Soil organic C and TN levels at the high PET site were 50% less than at the low and medium PET sites, and toeslope soils were 30% greater than summit and sideslopes. Annualized stover biomass explained 80% of the variation in SOC and TN in the 0‐ to 10‐cm soil profile. Cropping systems that eliminate summer fallowing are maximizing the amount of SOC and TN sequestered.