EVALUATING MINE SOIL PREPARED BY SCRAPER PANS FOR HERBACEOUS PLANTS AND PINE SEEDLINGS AT AN EAST TEXAS LIGNITE SURFACE MINE

Author

Hannah Z. AngelFollow

Date of Award

Fall 8-12-2017

Degree Type

Thesis

Degree Name

Master of Science - Forestry

Department

Forestry

First Advisor

Dr. Hans Williams

Second Advisor

Dr. Jeremy Stovall

Third Advisor

Dr. Kenneth Farrish

Fourth Advisor

Dr. Brian Oswald

Abstract

Since 1974, Luminant Mining Company, LLC (Luminant) has planted over 38.7 million trees on its reclaimed lignite surface mine operations in Texas. For decades, the use of improved reclamation techniques on Luminant’s mined lands have resulted in over 31,160 ha reclaimed to forests, wildlife habitat, and pastures with productivity levels similar to those found on unmined lands. The development of new reclamation methodologies offers opportunities to further improve productivity of planted trees at Luminant’s Martin Lake Oak Hill Mine in east Texas. The conventional haulback or ‘truck shovel’ reclamation method uses haul trucks for the selective transport and placement of oxidized overburden to serve as the reforestation growth medium. Transport and placement of overburden can also be accomplished using scraper pans. Operating scraper pans is more cost effective than the truck shovel method; thus, there is a desire to institute scraper pans as the primary method of reclamation. However, given a lack of information, there are concerns of the effects of scraper pans on mine soil compaction and vegetative establishment.

To address the potential compacting effects of scraper pans, four soil tillage treatments replicated five times were implemented at the Oak Hill Mine in August 2015 using a randomized complete block design: 1) No Tillage (control); 2) Disking (30-35 cm depth); 3) Single-Ripping (90 cm depth)/Disking (30-35 cm depth); and, 4) Cross-Ripping (90 cm depth)/Disking (30-35 cm depth). Soil physical and chemical properties were investigated at 0-30, 30-60, and 60-90 cm depth intervals. After one growing season, vegetative response was measured for an herbaceous winter cover crop in May 2016 and for loblolly pine (Pinus taeda L.) tree seedlings in October 2016.

Aboveground biomass production of the winter cover crop was highest on the ripped treatments. The untilled control resulted in the lowest herbaceous establishment and growth. Loblolly pine tree seedling survival across all treatments exceeded the standard for mined lands in this region. Highest survival occurred on the tilled plots (> 90%) compared to the control (85%) (p < 0.10). Cross-ripping was superior in terms of lowering soil bulk density (1.36 Mg m^-3) and soil strength (2,220 kPa), and increasing tree seedling relative volume index growth (32 cm³) (p < 0.10). Above and belowground biomass of loblolly pine seedlings showed significant treatment effects (p < 0.10) and followed similar trends to seedling volume growth. In summary, disking alone improved herbaceous cover and pine seedling survival, while cross-ripping coupled with disking provided the most favorable responses in mine soil physical properties and vegetative growth.

Repository Citation

Angel, Hannah Z., "EVALUATING MINE SOIL PREPARED BY SCRAPER PANS FOR HERBACEOUS PLANTS AND PINE SEEDLINGS AT AN EAST TEXAS LIGNITE SURFACE MINE" (2017). Electronic Theses and Dissertations. 113.
https://scholarworks.sfasu.edu/etds/113

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