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Title: Soil C dynamics in a 26-year CRP chronosequence on an Amarillo fine sandy loam

item FULTZ, LISA - Texas Tech University
item KAKARLA, MAMATHA - Texas Tech University
item MOORE-KUCERA, JENNIFER - Texas Tech University
item Acosta-Martinez, Veronica
item ZAK, JOHN - Texas Tech University
item HORITA, JUSKE - Texas Tech University
item Calderon, Francisco

Submitted to: ASA-CSSA-SSSA Annual Meeting Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 11/3/2014
Publication Date: 11/6/2014
Citation: Fultz, L., Kakarla, M., Moore-Kucera, J., Acosta Martinez, V., Zak, J.C., Horita, J., Calderon, F.J. 2014. Soil C dynamics in a 26-year CRP chronosequence on an Amarillo fine sandy loam[abstract]. American Society of Agronomy, Crop Science Society of America, Soil Science Society of America. November 3-6, 2014, Tampa, Florida. Paper No. 78611.

Interpretive Summary:

Technical Abstract: The Conservation Reserve Program (CRP) sequesters more carbon (C) on private lands than any other federally administered program, but the rate and maximum amount of sequestered SOC is dependent on inherent soil properties (e.g. texture), local climate, and initial restoration efforts. We estimated the change in SOC dynamics in a 26-yr chronosequence of cultivated fields (predominantly cotton) restored to C4 grasses (monoculture and mixed) on an Amarillo fine sandy loam. In 2012, 7 dryland cropland fields (0 years) and 16 CRP fields that ranged from 6 to 26 years under CRP were sampled (0-10 and 10-30 cm) and in situ soil respiration (CO2) was measured. Metabolic quotient (qCO2) was calculated as the ratio of CO2-flux to microbial biomass C. Particulate organic matter (POM) was isolated using a combination of size and density fractionation techniques. POM-C and whole-SOC content and d13C were measured to determine relative fraction (Fc) of C from C4 plants. qCO2 decreased with years restored (from 3.6 to 1.4 µg CO2-C mg-1 Cmic h-1). Whole-SOC was not significantly affected by years restored, however POM-C and the microbial biomass C-to-SOC ratio increased with years restored (0.63 to 1.38 Mg ha-1 and 0.02 to 0.05, respectively) indicating an increase in the more labile C pools. Within the POM fraction, SOC at 0-yrs was primarily from C3 sources (cotton) as opposed to relict C4 grasses (62 and 38%, respectively). After 13-yrs in CRP, the proportion of POM-C from C4 grasses increased to 85% with no further increase measured up to 26 years under restoration. To determine potential for ecosystem recovery 3 native short-grass prairie fields have been identified and will be examined for the same soil parameters.