Accumulation of Nitrogen in Minesoils Seeded to Black Locust

Nitrogen accumulation in minesoils developing in replaced coal surface‐mine overburden seeded with black locust (Robinia pseudoacacia L.) was surveyed. Nitrogen increased significantly with age from 5 to 18 years at depths of 0 to 5, 5 to 10, and 10 to 15 cm, until it equaled or exceeded that in adjacent, native soils; however, the rate of increase was slower in the lower depths. Averages of the N content in all three depths showed that the oldest age group of minesoils (16 to 18 years) accumulated 2,974 kg/ha under black locust, which was slightly higher than the 2,808 kg/ha of N found in an adjacent native soil under mixed hardwood.