Penn State Soil Characterization Lab
Soil is an integral part of ecosystem function. There are 29 million acres (11,735,884 hectares) of soil in Pennsylvania supporting: wetlands; forest lands; agricultural lands; urban lands; homes, businesses, and roads; our drinking and wastewater filtration. Without soil, these activities and functions would be much more difficult and in some cases even impossible, for soil is as precious to our lives as the very blood in our bodies.
Research in the Soil Characterization Laboratory focuses on people’s use of landscapes and the accompanying changes in soil function across the larger ecosystem the soil supports. Dr. Drohan’s research group addresses basic science questions, but also demonstrates how this new knowledge can be applied to improve land management and ecosystem stability.
Soil Characterization Lab News
Could vacant lots double as green infrastructure projects?
April 15, 2014"The idea of using green infrastructure, from rain gardens and rain buckets to porous streets and simple sidewalk grass and plantings, is among the few environmental solutions that exists virtually unopposed. Big, old cities in the U.S. tend to have outdated sewer systems that overflow when it rains a lot, thanks to the built environment’s inability to slow all that water down."
NEW PAPER: Residential demolition and its impact on vacant lot hydrology: Implications for the management of stormwater and sewer system overflows
March 28, 2014W.D. Shuster, S. Dadio, P. Drohan, R. Losco, J. Shaffer. Increased residential demolitions have made vacant lots a ubiquitous feature of the contemporary urban landscape. Vacant lots may provide ecosystem services such as stormwater runoff capture, but the extent of these functions will be regulated by soil hydrology. We evaluated soil physical and hydrologic characteristics at each of low- (backyard, fenceline) and high-disturbance (within the demolition footprint) positions in 52 vacant lots in Cleveland, OH, which were the result of different eras of demolition process and quality (i.e., pre-1996, post-1996). Penetrometer refusal averaged 56% (range: 15–100%) and was attributed to high concentration of remnant buried debris in anthropogenic backfill soils. Both disturbance level and demolition type significantly regulated infiltration rate to an average of 1.8 cm h−1 (range: 0.03–10.6 cm h−1). Sub-surface saturated hydraulic conductivity (Ksat) averaged higher at 4.0 cm h−1 (range: 0–68.2 cm h−1), was influenced by a significant interaction between both disturbance and demolition factors, and controlled by subsurface soil texture and presence/absence of unconsolidated buried debris. Our observations were synthesized in rainfall-runoff models that simulated average, high- and low-hydrologic functioning, turf-dominated, and a prospective green infrastructure simulation, which indicated that although the typical Cleveland vacant lot is a net producer of runoff volume, straightforward change in demolition policy and process, coupled with reutilization as properly designed and managed infiltration-type green infrastructure may result in a vacant lot that has sufficient capacity for detention of the average annual rainfall volume for a major Midwestern US city.
NEW PAPER: Turnover of soil carbon following addition of switchgrass-derived biochar to four soils
January 17, 2014Binh T. Nguyen, Roger T. Koide, Curtis Dell*, Patrick Drohan, Howard Skinner, Paul R. Adler, and Andrea Nord. Amending soils with biochar can sequester C and improve soil properties, such as nutrient holding capacity and water retention. While biochars generally have a long residence time in soil, the turnover of biochar-C can be influenced by both biochar characteristics and soil properties. Biochar can also potentially alter the rate of decomposition of native soil organic matter (SOM). The turnover of switchgrass-derived biochar-C was evaluated in the laboratory using soil from four marginally productive sites in central Pennsylvania. Carbon dioxide emissions from unamended soil, biochar-amended soil, and pure biochar were monitored during 189 day incubations, and data was fit to a two-pool exponential model to estimate the amount and mean residence time (MRT) of C in labile and stable pools. Carbon-13 signatures of emitted CO2 were also determined to estimate the proportion of emitted CO2 derived from the biochar. Mixing biochar with each of the soils reduced the apparent MRT of C in both labile and stable pools, but the magnitude of change depended on the soil. Overall the biochar was largely stable in each soil, with only 1.1 to 2.1 % of the added biochar-C emitted during incubation. There was no measurable effect of biochar amendment on turnover of native SOM in any of the soils. Therefore, we conclude that amendment of our soils with switchgrass-derived biochar can effectively increase net C sequestration.