Greater humification of belowground than aboveground biomass carbon into particulate soil organic matter in no-till corn and soybean crops |
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| Affiliation: | 1. Facultad de Agronomía, Estación Experimental Mario Alberto Cassinoni, Universidad de la Republica, Ruta 3, km 363, Paysandú 60000, Uruguay;2. Department of Plant Science, The Pennsylvania State University, 116 ASI Building, University Park, PA 16802, USA;3. School of Earth Sciences, Woods Institute for the Environment, and Precourt Institute for Energy, Stanford University, Stanford, CA, USA;4. IFEVA/CONICET, Facultad de Agronomía, Universidad de Buenos Aires, Av. San Martín 4453, Buenos Aires C1417DSE, Buenos Aires, Argentina;5. Unidad de Sistemas Ambientales, Facultad de Agronomía, Universidad de la República, Av. E. Garzón 780, Montevideo, Uruguay;1. Instituto de Recursos Naturales y Agrobiología de Sevilla, IRNAS-CSIC, PO Box 1052, 41080, Sevilla, Spain;2. Department of Chemistry and Biochemistry, Physical Sciences Building, Old Dominion University, 4402, Elkhorn Avenue, Norfolk, VA, 23529, United States;1. Graduate Program in Organismic and Evolutionary Biology, 204C French Hall, University of Massachusetts Amherst, 230 Stockbridge Road, Amherst, MA 01003, United States;2. Department of Natural Resources and the Environment, University of New Hampshire, Durham, NH 03824, United States;3. The Ecosystems Center, 7 MBL Street, Woods Hole, MA 02543, United States;4. Department of Microbiology, 418 Morrill Science Center IVN, University of Massachusetts Amherst, 639 North Pleasant Street, Amherst, MA 01003, United States;1. CONICET, CERZOS-UNS, Argentina;2. Departamento de Agronomía, UNS, Argentina;3. Comisión de Investigaciones Científicas (CIC), CERZOS-UNS, Argentina;4. AER INTA Cañada de Gómez, Argentina;1. State Key Laboratory of Forest and Soil Ecology, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110164, China;2. Institute of Agricultural and Regional Planning, Chinese Academy of Agricultural Sciences, Beijing 100081, China;3. Institute of Soil and Fertilizer Sciences, Jilin Academy of Agricultural Sciences, Changchun 130124, China;4. College of Land & Environment, Shenyang Agricultural University, Shenyang 110866, China;5. National Field Research Station of Shenyang Agroecosystems, Shenyang 110016, China |
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| Abstract: | Quantifying the amount of carbon (C) incorporated from decomposing residues into soil organic carbon (CS) requires knowing the rate of C stabilization (humification rate) into different soil organic matter pools. However, the differential humification rates of C derived from belowground and aboveground biomass into CS pools has been poorly quantified. We estimated the contribution of aboveground and belowground biomass to the formation of CS in four agricultural treatments by measuring changes in δ13C natural abundance in particulate organic matter (CPOM) associated with manipulations of C3 and C4 biomass. The treatments were (1) continuous corn cropping (C4 plant), (2) continuous soybean cropping (C3), and two stubble exchange treatments (3 and 4) where the aboveground biomass left after the grain harvest was exchanged between corn and soybean plots, allowing the separation of aboveground and belowground C inputs to CS based on the different δ13C signatures. After two growing seasons, CPOM was primarily derived from belowground C inputs, even though they represented only ∼10% of the total plant C inputs as residues. Belowground biomass contributed from 60% to almost 80% of the total new C present in the CPOM in the top 10 cm of soil. The humification rate of belowground C inputs into CPOM was 24% and 10%, while that of aboveground C inputs was only 0.5% and 1.0% for soybean and corn, respectively. Our results indicate that roots can play a disproportionately important role in the CPOM budget in soils. Keywords Particulate organic matter; root carbon inputs; carbon isotopes; humification rate; corn; soybean. |
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| Keywords: | Particulate organic matter Root carbon inputs Carbon isotopes Humification rate Corn Soybean |
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