Persistence of subsoiling effects on the soil physical and hydraulic properties in a reconstructed soil

  • Author / Creator
    Hebb, Christina C
  • Surface mining is one of the most significant forms of anthropogenic disturbance to natural and managed ecosystems. In Alberta, mining disturbs large areas in the Mixedwood Boreal natural region and recovery is often slow because of poor soil quality, specifically the high degree of compaction. Soil compaction, caused by repeated traffic of heavy machinery during soil reconstruction of surface mined lands, hinders the re-establishment of vegetation. Compaction causes changes to soil physical properties such as increased bulk density and reduced macroporosity which reduce soil infiltration capacity, drainage and water holding capacity. The disruption of the soil water balance as a result of these compaction-induced changes to the soil further negatively effects the chemical and biological functioning in the soil because of poor aeration. In compacted forest soils, subsoiling with heavy-duty rip ploughs has been shown to be an effective method at ameliorating compaction by breaking up large compacted layers, into smaller aggregates and peds which significantly increases macroporosity, infiltration, drainage and aeration. The main objective of this research is to quantify any medium-term (~ 4 yrs) benefits of subsoiling with a heavy-duty rip plough on reconstructed soil at a coal mine. In 2010, an experimental research site was established at the Genesee Prairie Mine, 70 km west of Edmonton to investigate the potential for compaction amelioration using a McNabb winged subsoiler D7R XR to a 60 cm depth. Results showed that medium-term effects of ripping are variable with depth. Ripping effects on pore size distribution, saturated hydraulic conductivity, and bulk density were most pronounced in the 15-20 cm depth. Infiltration rates were increased by ripping which is expected to reduce hydraulic barriers at the soil surface. Evidence suggests non-ripped surface layers (5-10 cm depth) showed improvements in soil properties (bulk density, saturated hydraulic conductivity) as a result of natural processes (i.e., plant root expansion and drying-shrinkage). Over time, it appears that the effects of ripping have decreased, with a simultaneous improvement in non-ripped soils.

  • Subjects / Keywords
  • Graduation date
    Spring 2016
  • Type of Item
  • Degree
    Master of Science
  • DOI
  • License
    This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.