Abstract
Cattle Production from Rehabilitated Coal Mine Pastures in Southern Queensland: Results from the Acland Grazing Trial.
The Acland grazing trial aims to evaluate the viability and sustainability of cattle production from rehabilitated mined land compared with surrounding unmined lands. This paper compares pasture and cattle production from rehabilitated and unmined land at New Hope’s Acland mine near Toowoomba in Southern Queensland’s Brigalow region and is based on 4 years (2014-17) of soil, pasture and cattle field observations.
Angus steers and heifers are rotationally grazed on three rehabilitated (Rehab) paddocks previously used for open cut coal mining (2003-2011) plus an unmined sown pasture control paddock planted in 2012. As the mine moved across the landscape the rehab paddocks were sequentially planted to sown pastures from 2007 to 2011; mainly Rhodes grass and Bissett creeping blue grass with panic, Queensland blue grass, medic and vetches also present. Regular cattle weighing and pasture measurements were used to adjust stock numbers and thus maintain equivalent grazing pressures across paddocks. Soil and pasture production characteristics are also monitored on surrounding unmined lands at 8 benchmark pasture sites in the district. Soils in the area are typically red and brown dermosols and black vertosols and have had a history of cultivation. Rehab soils typically have 50 cm of topsoil with pasture roots penetrating the underlying argillaceous overburden from the Walloon coal measures. Differences between rehabilitated and control sites are small regards salinity, sodicity and plant available phosphorus and nitrogen. The GRASP grazing systems model is used to evaluate key performance indicators during the trial period and to assess the productivity of rehab paddocks compared to the productivity of unmined lands.
Livestock generally performed better over the trial period on rehabilitated sites in terms of weight gain, annual beef production, stocking rate and stock grazing days. Results varied with season and all four sites had the highest performance in at least one grazing. Mean annual live weight gain from the Rehab pastures for the 2014-2017 period was estimated to be 186 kg/head/yr (0.51 kg/head/day) and 97 kg/ha/yr compared with 156 kg/head/yr (0.43 kg/head/day) and 56 kg/ha/yr from unmined land. Liver tissue tests for contaminants did not reveal any results outside the expected range.
Mean annual pasture production for the three Rehab paddocks for the period 2014-2017 was 5317 kg/ha compared with a mean of 3264 kg/ha for the Control paddock and benchmark sites on unmined land. Pasture rundown in the future may reduce productivity of Rehab pastures and thus identifying long-term sustainable production is a significant challenge.
Cattle Production from Rehabilitated Coal Mine Pastures in Southern Queensland: Results from the Acland Grazing Trial.
The Acland grazing trial aims to evaluate the viability and sustainability of cattle production from rehabilitated mined land compared with surrounding unmined lands. This paper compares pasture and cattle production from rehabilitated and unmined land at New Hope’s Acland mine near Toowoomba in Southern Queensland’s Brigalow region and is based on 4 years (2014-17) of soil, pasture and cattle field observations.
Angus steers and heifers are rotationally grazed on three rehabilitated (Rehab) paddocks previously used for open cut coal mining (2003-2011) plus an unmined sown pasture control paddock planted in 2012. As the mine moved across the landscape the rehab paddocks were sequentially planted to sown pastures from 2007 to 2011; mainly Rhodes grass and Bissett creeping blue grass with panic, Queensland blue grass, medic and vetches also present. Regular cattle weighing and pasture measurements were used to adjust stock numbers and thus maintain equivalent grazing pressures across paddocks. Soil and pasture production characteristics are also monitored on surrounding unmined lands at 8 benchmark pasture sites in the district. Soils in the area are typically red and brown dermosols and black vertosols and have had a history of cultivation. Rehab soils typically have 50 cm of topsoil with pasture roots penetrating the underlying argillaceous overburden from the Walloon coal measures. Differences between rehabilitated and control sites are small regards salinity, sodicity and plant available phosphorus and nitrogen. The GRASP grazing systems model is used to evaluate key performance indicators during the trial period and to assess the productivity of rehab paddocks compared to the productivity of unmined lands.
Livestock generally performed better over the trial period on rehabilitated sites in terms of weight gain, annual beef production, stocking rate and stock grazing days. Results varied with season and all four sites had the highest performance in at least one grazing. Mean annual live weight gain from the Rehab pastures for the 2014-2017 period was estimated to be 186 kg/head/yr (0.51 kg/head/day) and 97 kg/ha/yr compared with 156 kg/head/yr (0.43 kg/head/day) and 56 kg/ha/yr from unmined land. Liver tissue tests for contaminants did not reveal any results outside the expected range.
Mean annual pasture production for the three Rehab paddocks for the period 2014-2017 was 5317 kg/ha compared with a mean of 3264 kg/ha for the Control paddock and benchmark sites on unmined land. Pasture rundown in the future may reduce productivity of Rehab pastures and thus identifying long-term sustainable production is a significant challenge.
Presentation
Cattle Production from Rehabilitated Coal Mine Pastures in Southern Queensland: Results from the Acland Grazing Trial
Presented on 12th April 2018 at the 8th Annual Best Practice Ecological Rehabilitation of Mined Lands Conference (2018)
tom_newsome_cattle_production_from_rehabilitated_coal_mine_pastures_in_southern_queensland.pdf |