Greater humification of belowground than aboveground biomass carbon into particulate soil organic matter in no - till corn and soybean crops
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 ?13C 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 ?13C signatures. After two growing seasons, CPOM was primarily derived from belowground C inputs, even though they represented only ~10 percent of the total plant C inputs as residues. Belowground biomass contributed from 60 percent to almost 80 percent of the total new C present in the CPOM in the top 10cm of soil. The humification rate of belowground C inputs into CPOM was 24 percent and 10 percent, while that of aboveground C inputs was only 0.5 percent and 1.0 percent 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.
| Main Authors: | , , , , |
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| Format: | Texto biblioteca |
| Language: | spa |
| Subjects: | ZERO TILLAGE, ZEA MAYS, STABILIZATION, SOYBEAN, SOILS, SOIL ORGANIC MATTER, ROOT SYSTEM, ROOT CARBON INPUTS, PARTICULATE ORGANIC MATTER, ORGANIC COMPOUNDS, ORGANIC CARBON, LAKES, ISOTOPES, HUMIFICATION RATE, HUMIFICATION, GROWING SEASON, GLYCINE MAX, CROPPING PRACTICE, CORN, CARBON SEQUESTRATION, CARBON ISOTOPES, CARBON ISOTOPE, CARBON, BUDGET CONTROL, BIOMASS, BIOLOGICAL MATERIALS, BIOGEOCHEMISTRY, BIODEGRADATION, BELOWGROUND BIOMASS, ABOVEGROUND BIOMASS, , |
| Online Access: | http://ceiba.agro.uba.ar/cgi-bin/koha/opac-detail.pl?biblionumber=47168 http://ceiba.agro.uba.ar/cgi-bin/koha/opac-detail.pl?biblionumber= http://ceiba.agro.uba.ar/cgi-bin/koha/opac-detail.pl?biblionumber= |
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| Summary: | 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 ?13C 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 ?13C signatures. After two growing seasons, CPOM was primarily derived from belowground C inputs, even though they represented only ~10 percent of the total plant C inputs as residues. Belowground biomass contributed from 60 percent to almost 80 percent of the total new C present in the CPOM in the top 10cm of soil. The humification rate of belowground C inputs into CPOM was 24 percent and 10 percent, while that of aboveground C inputs was only 0.5 percent and 1.0 percent 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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