[Objective] The effect of biological humic acid on soil improvement in open-pit mine dump was studied

in order to provide scientific references for the improvement of soil quality.[Methods] Biological humic acid with different contents(0-400 kg/hm2) were added in five different kinds of soil which were derived from five land use types(Robinia pseudoacacia forest

Ulmus pumila forest

Vitex negundo forest

farming land and unutilized land). Pot experiments were conducted by planting Lolium multiflorum species. The effects of biological humic acid on soil improvement were investigated.[Results] The maximum emergence rate for the soil from R. pseudoacacia

U. pumila

V. negundo

farming and unutilized land occurred when the amounts of biological humic acid were 200

200

300

300 and 200 kg/hm2

respectively. The maximum amount of biological humic acid required by Lolium multiflorum seedling for five different kinds of soil were 200

200

200

300 and 300 kg/hm2. The maximum root length occurred when the amounts of biological humic acid were 300

100

300

300 and 300 kg/hm2

respectively

and the maximum biomass occurred when the amount were 200

100

200

300 and 300 kg/hm2

respectively. As the biological humic acid increases

all the seedling emergence

seedling height

root length and seedling biomass showed a downward trend before an increase.[Conclusion] There was a dose effect of the biological humic acid on the plant regeneration and growth in different soil of open-pit mine dump. The change curves of the relations for the plant regeneration and growth and the biological humic acid appeared as a "single-peak" shape

which indicate that a balanced amount of biological humic acid could improve the vegetation recovery in open-pit mine dump.