A greenhouse study was conducted to evaluate the fertility status of six overburdens from the potential lignite mining area of Louisiana. Subterranean clover (Trifolium subterraneanL. cv. woogenellup) was grown in 2.5 kg of each overburden material which was treated with 0, lx, 2x, 4x and 8x the recommended rate of fertilizer containing P and K based on state soil test analyses. Plants were grown for 14 weeks and harvested to evaluate dry matter yield and mineral composition.