A comparison of rehabilitated coal mine soil and unmined soil supporting grazed pastures in south-east Queensland

Land that is disturbed by mining activities is required to undergo suitable rehabilitation. This study compared soils supporting grazed pasture on land that was rehabilitated after coal mining activity with that on unmined land. Pasture biomass, and soil physical and chemical properties important for pasture production and sustainability were intensively monitored on three sites that had completed rehabilitation at different times over the last 10 years, and one unmined control site. A further 18 unmined grazing sites were monitored for benchmarking purposes. Analysis of soil properties of plant available phosphorus and nitrogen, salinity and sodicity in the first year of the study suggested little difference in terms of benefits or constraints to pasture production between the rehabilitated and control sites. Plant-available phosphorus was sufficiently high in the two oldest rehabilitated sites that a fertiliser response would not be expected. Soil depth and the pasture rooting depth at the rehabilitated sites were at the shallow end of the wide range observed across the benchmark and control sites. Higher pasture biomass at the rehabilitated sites compared with the control at the initiation of the trial was attributed more to differences in grazing history than differences in soil attributes