Open Cut » Environment
This study follows on from project C23053 which found that cattle weight gain from pastures on ehabilitated mine land compared favourably and in most periods exceeded weight gain from similar cattle on adjacent analogue areas.
This project was aimed at addressing four questions:
- What lessons can be learned by reviewing past and present mine rehabilitation pasture work?
- How long does it take to re-establish a sustainable pasture on rehabilitated mine land?
- Were the two sites monitored in C23053 representative of other mine rehabilitation pasture work in the Hunter Valley?
- What research is needed to improve success of future mine land rehabilitation to pasture for grazing?
To answer these questions, the project undertook a desktop review of monitoring data from 107 rehabilitation to pasture sites established between 1993 and 2018 and 15 natural pasture analogue sites in the Hunter Valley coal region. The data primarily included pasture and soil results, but some also included indirect estimates of livestock performance. It was hoped to link this data with site establishment and management records to answer the project's core questions. However, issues were encountered with incompatible monitoring data and lack of establishment and management information. To still address the project's key questions, a combination of; monitoring results, grazing trial data, publications on mine rehabilitation practices in the Hunter, discussions with government and mine personnel and the authors' observations were used instead.
The review data was further supplemented by field assessments of pastures and soils at 20 sites where rehabilitated pastures were deemed to have been successfully established. The field data was used to 1) provide a more detailed comparison with the pasture compositions of C23053 project sites, and 2) determine the sequence of soil development over time, under mine rehabilitation pastures.
The desktop review concluded that the use of variable monitoring techniques, short lived sampling, low sampling intensities, little to old data and a focus on ecological outcomes rather than agricultural productivity made it too difficult to determine successful or unsuccessful rehabilitation practices in the aggregated data set.
Five measures were used to address the question “How long does it take to re-establish a sustainable pasture on rehabilitated mine land?”. These are described in detail in the project report.