Soil changes during stockpiling and after reclamation at three Wyoming natural gas production areas Jay Norton and Calvin Strom University of Wyoming 217 Joint Conference of the American Society of Mining and Reclamation Mine Drainage Task Force Appalachian Regional Reforestation Initiative Morgantown, West Virginia April 12, 217
Soil Function in aridisols and aridic alfisols A horizon: interface with atmosphere: OM accumulation and ELUVIATION; loss of clays, solutes; More OM, coarser texture, lower EC & ph than other horizons; Water infiltration & holding; nutrient cycling (microbes) Germination/establishment; B horizon: zone of accumulation of clays and solutes: ILLUVIATION Less OM, finer texture, higher EC & ph Water holding in finer texture
One size fits all Salvage & reclamation procedures
Pre disturbance: ABSTON FINE, SMECTITIC, FRIGID USTIC NATRARGIDS A E Bt Btn1 sandy loam clay Scraping depth Btn2 Bk Cr
After reclamation: ENTISOL Topsoil Clay Clay loam loam Subsoil
Loss of A horizon reduces already slim chances for germination & establishment Lifeless: little SOM to support microbial activity and nutrient cycling; Finer: inhibits water infiltration and facilitates evaporation; Drier: less OM and fine texture decrease plant-available water; Saline: EC > 4; osmotic potential and ion toxicity slow germination; Sodic: ESP > 15 disperses aggregates, exacerbating the above.
Pipelines + P&A + Active wells 29,683 Currently Producing Wells On File 121,626 Total Wells On File (DrillingEdge.com)
Great Divide and Green River Basins Objectives: determine short and longer-term effects of natural gas development and reclamation on soil quality across a precipitation gradient. Effects of topsoil depth on organic matter dynamics 11 inches Aridisols and Entisols formed in saline and sodic marine shales. 9 inches 7 inches
Soil Organic Matter Pools STRUCTURAL SOM METABOLIC SOM ACTIVE SOIL ACTIVE C SOM SLOW SOIL Slow C SOM PASSIVE SOM LOSSES: Harvest, CO 2 & N 2 O emissions, erosion etc. PLANT RESIDUE Active, or labile, SOM: Annual turnover Mineral N Mineralizable C& N dissolved organic C & N; Microbial C & N; light fraction C & N. Slow, or protected, SOM: Decades; Same as labile, but protected from mineralization within soil structure. Passive, or stabile, SOM: Centuries to millennia; Humus; Mineral-associated C & N;
Pinedale Anticline Elevation: 244 meters MATmax: 11 C MATmin: -6.6 C MAP: 276 mm Annual CV: 26.5% Fine-loamy, mixed, superactive, frigid Calcidic Haplustalfs Precipitation (mm) 7 6 5 4 3 2 1 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec 3 2 1-1 -2-3 Temperature (C)
Jonah Field Elevation: 214 meters MATmax: 11.9 C MATmin: -7.2 C MAP: 232 mm Ann CV: 27% Fine-loamy, mixed, superactive, frigid Calcidic Haplustalfs Precipitation (mm) 6 5 4 3 2 1 Total Precipitation Max. Temperature Min. Temperature Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec 3 2 1-1 -2-3 Temperature (C)
Wamsutter/Great Divide Basin Elevation: 265 meters MATmax: 13.2 C MATmin: -2.6 C MAP: 18 mm Ann CV: 32% Fine-loamy, mixed, superactive, frigid Typic Haplargids Precipitation (mm) 6 5 4 3 2 1 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec 3 2 1-1 -2-3 Temperature (C)
Three new well pads sampled at each field starting in 29 (9 points composited) 1. Predisturbance; 2. Stockpile; 3. Respread; 4. 1 year later; 5. 7 years later.
Soil samples from -5, 5-2, and 2-3 cm Stockpiles: Three points sampled to 25 cm
Data Collection Vegetation cover Physical properties: bulk density, texture Chemical properties: ph, EC Biological properties (total and labile soil organic matter): Total soil organic carbon and nitrogen; Mineral nitrogen; Dissolved organic carbon and nitrogen; Mineralizable organic carbon and nitrogen.
Jonah, 211 Jonah, 216
Anticline, 211 Anticline, 216
Study Period Precipitation Pinedale Jonah Wamsutter Precipitation (mm) 45 4 35 3 25 2 15 1 5 29 21 211 212 213 214 215 216 29 21 211 212 213 214 215 216 29 21 211 212 213 214 215 216 16 14 12 1 8 6 4 2 Sep-Nov 29 21 211 212 213 214 215 216 Sep-Nov 29 21 211 212 213 214 215 216 Sep-Nov 29 21 211 212 213 214 215 216
Mineralizable C in stockpiles, 29 Pinedale Jonah Wamsutter CO 2 -C mineralized (mg kg -1 ) CO 2 -C mineralized (mg kg -1 ) CO 2 -C mineralized (mg kg -1 ) 1 2 3 4 5 1 2 3 4 5 2 4 6 8 5 May June 5 5 Depth (cm) 1 15 August Depth (cm) 1 15 Depth (cm) 1 15 2 2 2 25 25 25
Reclaimed: Soil texture Anticline Jonah Wamsutter Clay Content (%) 1 2 3 Clay Content (%) 1 2 3 Clay Content (%) 1 2 3 5 5 5 1 1 1 Depth (cm) 15 2 15 2 15 2 25 25 25 3 3 3 35 35 35 Reclaimed Undisturbed Undisturbed
Reclaimed: Soil texture Anticline Jonah Wamsutter Clay Content (%) 1 2 3 Clay Content (%) 1 2 3 Clay Content (%) 1 2 3 5 5 5 1 1 1 Depth (cm) 15 2 15 2 15 2 25 25 25 3 3 3 35 35 35 Reclaimed Undisturbed
Disturbance Effects 1. Undisturbed: high labile SOM concentrations, low mineral N concentrations (low net mineralization); 2. Pulse of labile and mineral nutrients after disturbance truncated in cold storage in stockpile; 3. Pulse of mineralization at expense of PMC and N; 4. Loss of mineral N, labile OM begins to rebound. PMN and Mineral N (mg kg -1 ) 3 25 2 15 1 5 Jonah Mineral N PMN PMC 3 25 2 15 1 5 PMC (mg kg -1 ) Predisturbance Stockpiled Reclaimed Reclaimed 1 yr -3 cm weighted averages
PMN and Mineral N (mg kg -1 ) 6 5 4 3 2 1 Anticline 6 5 4 3 2 1 PMC (mg kg -1 ) PMN and Mineral N (mg kg -1 ) 3 25 2 15 1 5 Jonah Mineral N PMN PMC 3 25 2 15 1 5 PMC (mg kg -1 ) Predisturbance Stockpiled Reclaimed Reclaimed 1 yr Predisturbance Stockpiled Reclaimed Reclaimed 1 yr Disturbance Effects -3 cm weighted averages PMN and Mineral N (mg kg -1 ) 5 45 4 35 3 25 2 15 1 5 Wamsutter 5 45 4 35 3 25 2 15 1 5 PMC (mg kg -1 ) Anticline: complicated by stockpile being moved at least twice. Predisturbance Stockpiled Reclaimed Reclaimed 1 yr
PMC and N (mg kg -1 ) 5 4 3 2 1 Loss of labile C and N Anticline 5 25 4 3 2 1 PMC and N (mg kg -1 ) 2 15 1 5 Jonah 25 2 15 1 5 PMC and N (mg kg -1 ) 25 2 15 1 5 Wamsutter 5 45 4 35 3 25 2 15 1 5 Mineral Nitrogen (mg kg -1 ) 35 3 25 2 15 1 5 All Well Fields
Soil Organic Carbon (%) 2.5 2. 1.5 1..5 Anticline.25.2.15.1.5 Soil Organic Carbon (%) 2.5 2. 1.5 1..5 Jonah.5.4.3.2.1.. 2.5.25 Recovery of SOM Change: predisturbance to seven years after reclamation. TOC TN % change Anticline 72 88 Jonah -45-197 Wamsutter 3.7-1.7 Soil Organic Carbon (%) 2. 1.5 1..5. Wamsutter.2.15.1.5
Conclusions Stockpiles in semiarid region may not be affected by depth, at least in the short-term; What about age? Compared with degraded reference sites, reclaimed sites seem to recover or exceed original SOM levels within seven years; Possibly due to increased herbaceous vegetation Potentially mineralizable carbon recovers more slowly; Possibly due to loss of soil structure, which protects labile SOM from mineralization, and continued accelerated mineralization, lack of woody species Interest in reclamation research is as variable as annual rainfall.
Thanks to Calvin Strom Cally Driessen Amber Mason Jennifer Faulkner Leann Naughton Luke Driessen Kristi Bear Todd Loubsky K.C. Harvey, Inc. Gary Austen, BP America Pete Guernsey, QEP Resources Ralph Swift, Encana Exploration UW School of Energy Resources Wyoming Reclamation & Restoration Center