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Title: Assessment of microbial biomass carbon and nitrogen of native and non-native perennial pasture soils using hyperspectral data

Author
item AULD, KEIRA - Redlands Community College
item PETERSON-MUNKS, BREKKE - Orise Fellow
item Starks, Patrick

Submitted to: ASA-CSSA-SSSA Annual Meeting Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 8/1/2015
Publication Date: 11/15/2015
Citation: Auld, K., Peterson-Munks, B., Starks, P.J. 2015. Assessment of microbial biomass carbon and nitrogen of native and non-native perennial pasture soils using hyperspectral data [abstract]. ASA-CSSA-SSSA Annual Meeting. Synergy in Science: Partnering for Solutions, November 15-18, 2015, Minneapolis, Minnesota. Abstract number 316-3. Available: https://scisoc.confex.com/crops/2015am/webprogram/authorp.html.

Interpretive Summary: Abstract only.

Technical Abstract: Soil microbial biomass carbon (MBC) and nitrogen (MBN) are integral parts to soil organic matter. Increased production costs and chemical runoff can result from excessive application of fertilizer if these measurements are not used in total nutrient calculations. More timely and cost-effective methods are needed to assess MBC and MBN. Remote sensing may provide a timely and cost-effective solution. Although soil nutrients have been determined using reflectance data, no equation is published correlating hyperspectral reflectance data and MBC and MBN. A study at the USDA-ARS Grazinglands Research Laboratory, El Reno, OK was conducted in non-native, Old World Bluestem (Bothriochloa sp.) pastures and native, tallgrass prairie pastures to: 1) determine MBC and MBN content of soils, 2) obtain hyperspectral reflectance data of soils and 3) correlate MBC and MBN values with hyperspectral reflectance data. Bi-weekly soil sampling (0-15cm) occurred at toe-, mid- and upper-slope positions along four parallel and widely-spaced transects within pastures. Each soil sample was processed for MBC and MBN using standard chloroform fumigation methods to determine Total Organic Carbon. Bulk unfumigated and fumigated soils were dried at 65 ° C for 24 hr, ground to pass a 2-mm sieve and hyperspectral reflectance data obtained using an ASD FieldSpec FR radiometer. Soil reflectance and MBC and MBN concentrations were statistically analyzed using partial least square regression to determine if soil reflectance could be used for predicting MBC and MBN. Initial results indicated that utilizing hyperspectral soil data to determine soil MBC and MBN concentration is favorable (R2=0.65). Further study is needed to determine if this will be a suitable tool to determine MBC and MBN concentrations. Implications of this research could lead to real-time soil fertility decision making for reducing input costs and loss of excessive C and N to the environment.