Chapter 7 - Land reclamation open cast coal mine under semiarid conditions—a field-based observation

Abstract

Abstract The use of residual low rank coal (LRC) generated in a coal mine was evaluated as a possible humic amendment, enhanced by its microbial transformation, to improve edaphic material (EM) used in a constructed soil in postmining land reclamation. Low-rank residual coal from an open cast coal mine was evaluated as a possible humic amendment through microbial transformation, to improve the EMs used from soil built for land reclamation after coal extraction. Under field conditions, topsoil in plots of 25 m2 on land in the first stage of the rehabilitation process was treated with the following: Under field conditions, a land in the first stage of the rehabilitation process was divided into plots of 25 m2 and the topsoil was treated with the following: (1) powdered LRC at 2.5 ton/ha, (2) powdered LRC at 2.5 ton/ha inoculated with a consortium of coal solubilizing bacteria (CSB) that release humic substances from LRC, and (3) LRC–humic extract at 150 kg/ha. Plots without treatment were used as control; in all plots, buffel-grass (Cenchrus ciliaris) seeds were sown. After 12 months, an increase of up to 53% in cation exchange capacity was observed in LRC-treated plots; an increase of up to 83% in soil respiration (CO2 production) and up to 31% in microbiological activity is evaluated by hydrolysis of fluorescein diacetate. A relationship was found between the addition of LRC and the changes in the metabolic profile of soil microbial community; an increase of up to 96% in pore fraction greater than 30 μm after treatment with LRC was also found; no significant differences were found in the bulk density and soil aggregation parameters, nor was there any difference between the effect of CSB-inoculated and noninoculated LRC. The results provide evidence that it is possible to use LRC as an organic amendment in postmining land reclamation, although, apparently, the effect of LRC is independent on CSB inoculation.