370-7 What Happens to Soil Ecological Properties When Conservation Reserve Program Land Is Disturbed?.

See more from this Division: SSSA Division: Soil Biology & Biochemistry
See more from this Session: Role of Soil Microbial Communities and Processes in Ecosystem Reclamation and Restoration: I

Wednesday, November 18, 2015: 1:35 PM
Minneapolis Convention Center, 101 I

Chenhui Li, University of Missouri, Columbia, MO, Jennifer Moore-Kucera, Suite 800, USDA-NRCS, Portland, OR, Lisa M. Fultz, School of Plant, Environmental & Soil Science, LSU Agricultural Center - Baton Rouge, Baton Rouge, LA, Mamatha Kakarla, Texas Tech University, Lubbock, TX, Veronica Acosta-Martinez, USDA-ARS, Lubbock, TX, John C Zak, Biological Sciences, Texas Tech University, Lubbock, TX, David C. Weindorf, Texas Tech University, Texas Tech University, Lubbock, TX and Juske Horita, Geosciences, Texas Tech University, Lubbock, TX
Abstract:
Each year, expiring Conservation Reserve Program (CRP) contracts results in the conversion of restored CRP land back to croplands, potentially reversing multiple ecological benefits including C sequestration potential and microbial biodiversity. We evaluated microbial community composition (fatty acid methyl ester profiles) and a suite of dynamic soil C properties (DCPs) from soil samples (0-10cm, 10-30cm, and 30-50cm) collected from three long-term (>20 y) CRP fields and three CRP fields converted within 1-2 y in 2012 to dryland Crop production in 2012, 2013, and 2014. The DCPs include: microbial biomass C (MBC), particulate organic matter (POM-C), CO2 flux, and three C cycling soil enzyme activities. Arbuscular mycorrhizal fungi (AMF) and Gram positive bacteria (GM+) were largely responsible for differentiating between the two systems with greater AMF and lower GM+ bacteria in CRP than Crop. At 0-10cm, DCPs were similar between Crop and long-term CRP in 2012, but were different in 2013 and 2014. In general, CRP had greater MBC, POM-C, C-cycling activity than Crop. In contrast, DCPs at 10-30cm were greater in Crop than CRP across the three year sampling period. These increased soil C variables were attributed to increased microbial access to vegetative residues as grasses were terminated and incorporated into the soil during conversion. At 30-50cm, the DCPs were distinguished between Crop and CRP in 2012 only (Crop had greater MBC) but the treatments converged in subsequent years. Initially, CO2 fluxes were similar between the two systems with CRP producing more CO2 than Crop in 2013 and 2014. Soil qCO2 values (mg CO2-C released per mg MBC), however, indicated enhanced microbial metabolic efficiency in CRP than Crop and supports the need to couple these variables for ecological interpretation. CRP conversion to Crop altered the microbial community composition and decreased DCPs over time in two out of the three depths.

See more from this Division: SSSA Division: Soil Biology & Biochemistry
See more from this Session: Role of Soil Microbial Communities and Processes in Ecosystem Reclamation and Restoration: I