Background Soil nutrition is a basic limiting factor of plant growth, especially for ecological construction in arid area of northern China. In order to solve the problems of frequent soil and water loss and poor soil nutrients in arid mining areas, the pot-experiments of soil improvement were carried out using ameliorant. The application of soil amendment in arid zones can compensate the shortcomings above, and the optimal amount of it for different herbs still needs to be studied.

Methods The experiments took two herbs: Agropyron smithii and Medicago sativa and artificial zeolite as soil repairing materials (set 4 levels of 0, 5, 10, and 20 g/kg respectively). Undisturbed topsoil of 0-20 cm from each sample point was collected by soil drill. After sampling, the soil samples were mixed evenly for the pot-experiments. A total of 24 potted plants were cultivated in this study. After six months of plant growth, the nutrient indicators including plant biomass, soil microbial quantity (involving bacteria, fungi and actinomycetes), microbial biomass carbon (MBC), microbial biomass nitrogen (MBN) and available nitrogen, phosphorus, and kalium were measured.

Results 1) The combination of 2 herbaceous and artificial zeolite increased soil nutrient and promoted plant growth. The bacteria, fungi and actinomycetes in the soil increased by 11.02%, 15.25% and 50.67% respectively after the use of A. smithii combined with artificial zeolite. The soil MBC and MBN were 2.23 times and 2.68 times than that of the control group respectively. 2) The number of bacteria, fungi and actinomycetes after using M. sativa combined with artificial zeolite were 1.31, 2.29 and 9.55 times than before. Compared with no artificial zeolite precipitation, the available nitrogen, available phosphorus, and available potassium increased by 20.1%, 97.9% and 29.5% in the soil of M. sativa 3) Comprehensive analysis via principal component analysis (PCA) and cluster analysis showed that optimal artificial zeolite dosage of A. smithii and M. sativa were 20 and 10 g/kg respectively. The response of M. sativa soil to artificial zeolite was stronger under the condition of same amount of artificial zeolite content, nutrient changes in soil were more obvious than before adding it. M. sativa can be utilized as the pioneer herb for soil improvement in the district of Baiyen Obo.

Conculsions The results may provide scientific basis for plant cultivation, seed selection and ameliorant usage in arid mining areas and soil erosion area, and also provide reference for mine greening. The application of zeolite not only may balance the relationship between development of mining area and ecological protection, but also establish the foundation for land reclamation and space utilization through soil amelioration.