Root distribution is influenced by many soil and environmental factors in addition to the influence of genetics on crop morphology and overall plant vigor. The crop growth stage impacts the relative importance of root versus shoot development. Soil nutrient status and relative levels of nutrients in different parts of the soil profile conceivably could impact root distribution. In semi-arid environments, soil water availability is largely determined by irrigation practices once limited water from rainfall is depleted. Irrigation methods differ in the uniformity of water applications, ranging from nearly full surface application in solid-set sprinklers, dead-level basin, border checks to drip and furrow systems which may apply the water to a more limited portion of the soil. A three-year study was initiated under subsurface drip and furrow irrigation in cotton to evaluate the influence of growth stage, nitrogen fertilizer placement, irrigation method (furrow versus subsurface drip (SDI)), and amount applied per irrigation on root length density (RLD) and distribution within the soil profile. Furrow irrigated plots receiving 100% ETc had RLD values significantly lower than SDI plots in within-plant row cores, but much higher values within cores from the furrow area. Under full irrigation, the root system of SDI plants were more concentrated (higher RLD and root mass) near the emitter (within 35-45 cm) than near the soil surface or at greater depths or distances from the emitter. Amounts of applied fertilizer N and location of placement was found to impact root distribution and root length density.