Effects of Nitrogenous Fertilizer Application on the Establishment of Vegetation System in Weathered Particles of Coal Gob in Shanxi Mining Areas, China

Abstract

We conducted a greenhouse experiment to investigate the effects of nitrogenous fertilizer application on weathered particles of coal gob (WPCG). Different rates of nitrogenous fertilizer—low N (0.034 g N kg−1 WPCG), medium N (0.068 g N kg−1 WPCG), and high N (0.136 g N kg−1 WPCG)—were applied, and two native grasses (Orchardgrass and Alfalfa) were mix-planted in each pot. The results showed that the biomass production were all significantly increased in low and medium N group compared with that in the control group, respectively, in aboveground or underground part (p < 0.01), but it was slightly increased in high N group. Compared with the control group, chlorophyll concentrations of Orchardgrass in medium N group and Alfalfa in low N group were all significantly increased (p < 0.05), but it was the lowest in high N group. N uptake efficiency was the highest in low N group. However, N, P, and K uptake efficiencies were all lowest in high N group. Moreover, the microorganism population in WPCG was greatly improved in low N group. Compared with the control group, the numbers of bacteria, actinomycete, fungi, and nitrogen-fixing bacteria were significantly increased by 438%, 125%, 20%, and 258%, respectively (p < 0.05). After 120 days growth of Orchardgrass and Alfalfa, the percentage of particle diameter of WPCG was changed. The percentage of fine particles (<3 mm) was increased by 99.4%. In conclusion, it will be a more efficient approach for the quick establishment of vegetation system to apply low nitrogenous fertilizer (0.034 g N kg−1 WPCG) as an immediate treatment for nitrogen deficiency during the primary reclamation period on a large scale.