DOI: 10.5061/dryad.ns1rn8q4v
title: Historical land management alters new soil carbon inputs by annual and perennial bioenergy crops

description: Bioenergy and bioproduct markets are expanding to meet demand for climate
 friendly goods and services. Perennial biomass crops are particularly well
 suited for this goal because of their high yields, low input requirements,
 and potential to increase soil carbon (C). However, it is unclear how much
 C is allocated into belowground pools by perennial bioenergy crops and
 whether the belowground benefits vary with nitrogen (N) fertilizer inputs.
 Using in situ 13C pulse-chase labeling, we tested whether the
 sterile perennial grass Miscanthus × giganteus (miscanthus) or annual
 maize transfers more photosynthetic C to belowground pools. The experiment
 took place at two sites in Central and Northwest (NW) Iowa with different
 management histories and two nitrogen (N) fertilizer rates (0 and 224 kg N
 ha-1 yr-1) to determine if the fate of plant-derived soil C depends on
 soil fertility and crop type (perennial or annual). Maize allocated a
 greater percentage of total new 13C to roots than miscanthus, but
 miscanthus had greater new 13C in total and belowground plant biomass. We
 found strong interactions between site and most soil measurements –
 including new 13C in mineral and particulate soil organic matter (SOM)
 pools –which appear to be driven by differences in historical fertilizer
 management. The NW Iowa site, with a history of manure inputs, had greater
 plant-available nutrients (phosphorus, potassium, and ammonium) in soils,
 and resulted in less 13C from miscanthus in SOM pools compared to maize
 (approximately 64% less in POM and 70% less in MAOM). In more
 nutrient-limited soils (Central site), miscanthus transferred 4.5 times
 more 13C than maize to the more stable mineral-associated SOM pool. Our
 results suggest that past management, including historical manure inputs
 that affect a site’s soil fertility, can influence the net C benefits of
 bioenergy crops.
description: # Historical land management alters new soil carbon inputs by annual and
 perennial bioenergy crops Description of each file and the variables
 within each file (along with units) ## Files: ### "Soil C pools"
 contains C data for the four sampled soil zones: bulk, root bulk, near
 root, and rhizosphere Variables * Site = Name of farm. Allee is NW and
 Sorenson is Central * Block: experimental block, ranging from 1-4 within a
 site * Plot: experimental plot, one unique number across the experimental
 blocks within a site * NRate: Nitrogen fertilization rate (0 or 224 kg
 ha-1 N) * Crop: corn (maize) or miscanthus * SoilZone: four categories of
 soil pools separated at destructive harvest: bulk, root bulk, near root,
 and rhizosphere * Soil C: % soil C * Delta13C: the delta 13C signal of the
 sample * New C: the total new carbon (mg C/kg soil) derived from the
 labeled crop ### "POM\_MAOM new C" contains C data for the
 rhizosphere soil POM and MAOM pools Variables * Site = Name of farm. Allee
 is NW and Sorenson is Central * Block: experimental block, ranging from
 1-4 within a site * Plot: experimental plot, one unique number across the
 experimental blocks within a site * NRate: Nitrogen fertilization rate (0
 or 224 kg ha-1 N) * DeltaPOMC: the delta 13C signal of the POM sample *
 DeltaMAOMC: the delta 13C signal of the MAOM sample * NewCPOM: the total
 new particulate organic matter (POM) carbon (mg C/kg soil) derived from
 the labeled crop * NewCMAOM: the total new mineral associated organic
 matter (MAOM) carbon (mg C/kg soil) derived from the labeled crop ###
 "MBC\_SEOC\_data" contains microbial biomass C (µg C/gdw soil)
 and salt-extractable organic C (µg C/gdw soil) plus the delta 13C values
 for each pool. Variables * Site = Name of farm. Allee is NW and Sorenson
 is Central * Block: experimental block, ranging from 1-4 within a site *
 Plot: experimental plot, one unique number across the experimental blocks
 within a site * NRate: Nitrogen fertilization rate (0 or 224 kg ha-1 N) *
 Crop: corn (maize) or miscanthus * MBC: microbial biomass carbon (µg C/gdw
 soil) derived from chloroform fumigation extractions * SEOC:
 salt-extractable organic carbon (µg C/gdw soil) * Delta13C: the delta 13C
 signal of the sample (MBC or SEOC) ### "Plant clippings"
 contains the %C content and 13C signature of the corn (maize) and
 miscanthus leaf punches 24 hours after the labeling event. Variables *
 Site = Name of farm. Allee is NW and Sorenson is Central * Block:
 experimental block, ranging from 1-4 within a site * Plot: experimental
 plot, one unique number across the experimental blocks within a site *
 NRate: Nitrogen fertilization rate (0 or 224 kg ha-1 N) * Crop: corn
 (maize) or miscanthus * PercC: %C of sample * Delta13C: the delta 13C
 signal of the sample * AtomPerc: the atom % of the sample ### "plant
 component data" contains the %C content and 13C signature of both
 crops at harvest. Variables * Site = Name of farm. Allee is NW and
 Sorenson is Central * Block: experimental block, ranging from 1-4 within a
 site * Plot: experimental plot, one unique number across the experimental
 blocks within a site * NRate: Nitrogen fertilization rate (0 or 224 kg
 ha-1 N) * Crop: corn (maize) or miscanthus * Part: plant component:
 leaves, roots, stems, or kernels/flowers * PercC: %C of sample * Delta13C:
 the delta 13C signal of the sample ### "Plant New C" contains
 the new C (derived from 13C enrichment) data for plant biomass at harvest
 Variables * Site = Name of farm. Allee is NW and Sorenson is Central *
 Block: experimental block, ranging from 1-4 within a site * Plot:
 experimental plot, one unique number across the experimental blocks within
 a site * Crop: corn (maize) or miscanthus * New 13C in total plant biomass
 at harvest: the new plant biomass (above and belowground biomass) carbon
 derived from the 13C-labeled CO2 (g 13C ha-1) * Total new 13C in
 aboveground plant biomass at harvest: the new aboveground plant biomass
 carbon derived from the 13C-labeled CO2 scaled to one hectare (g 13C ha-1)
 * Total new 13C in belowground plant biomass at harvest: the new
 belowground plant biomass carbon derived from the 13C-labeled CO2 scaled
 to one hectare (g 13C ha-1) * Plant aboveground biomass: total aboveground
 plant biomass scaled to one hectare (Kg/ha) * Plant belowground biomass:
 total belowground plant biomass scaled to one hectare (Kg/ha) * Fraction
 of total new 13C belowground: the fraction of new plant biomass derived
 from the 13-C labeled CO2 that is belowground (% of total)