AbstractBarley (Hordeum vulgare L.) was grown in a greenhouse in incubated and nonincubated samples of a Cretaceous shale, two strip mine coal spoils, and a soil (Cryoboroll) to evaluate the significance to plant growth of indigenous N mineralization and utilization of added NH4+. These “soil” materials contained 730 to 1,190 ppm total N. Plants grown in the shale or fresh spoil took up less indigenous N than plants grown in vegetated spoil or in soil. Incubation did not significantly affect uptake of indigenous N from any of the four “soil” materials.Less N added as NH4+ was taken up by barley growing in incubated than nonincubated samples of shale, fresh spoil, and vegetated spoil. Total‐N uptake from incubated “soil” material was positively correlated with NH4+‐N + NO3‐‐N contents of “soil” material samples after laboratory incubation for 12, 21, and 42 days.This study indicated that while initial plant recovery of fertilizer N from the geologic materials equaled that recovered from the soil, fertilizer N added to the geologic material may be less available to plants with time than the same amount of fertilizer N added to soil. The high correlations between mineral N contents of laboratory‐incubated samples and total N uptake by barley grown under greenhouse conditions suggested that laboratory incubation tests could be useful in estimating the plant‐available N potentials of certain drastically disturbed lands prior to extensive revegetation programs.