DOI: 10.5061/dryad.547d7wmf3
title: Data from: Long-term changes in soil carbon and nitrogen fractions in switchgrass, native grasses, and no-till corn bioenergy production systems

description: Cellulosic bioenergy is a primary land-based climate mitigation strategy,
 with soil carbon (C) storage and nitrogen (N) conservation as important
 mitigation elements. Here, we present 13 years of soil C and N change
 under three cellulosic cropping systems: monoculture switchgrass (Panicum
 virgatum L.), a five native grasses polyculture, and no-till corn (Zea
 mays L.). Soil C and N fractions were measured four times over 12 years.
 Bulk soil C in the 0–25 cm depth at the end of the study period ranged
 from 28.4 (± 1.4 se) Mg C ha−1 in no-till corn, to 30.8 (± 1.4) Mg C ha−1
 in switchgrass, and to 34.8 (± 1.4) Mg C ha−1 in native grasses.
 Mineral-associated organic matter (MAOM) ranged from 60% to 90% and
 particulate organic matter (POM) from 10% to 40% of total soil C. Over 12
 years, total C as well as both C fractions persisted under no-till corn
 and switchgrass and increased under native grasses. In contrast, POM N
 stocks decreased 33% to 45% across systems, whereas MAOM N decreased by
 less than 13% and only in no-till corn. Declining POM N stocks likely
 reflect pre-establishment land use, which included alfalfa and manure in
 earlier rotations. Root production and large soil aggregate formation
 explained 69% (p &lt; 0.001) and 36% (p = 0.024) of total soil C
 change, respectively, and 60% (p = 0.020) and 41% (p = 0.023) of soil N
 change, demonstrating the importance of belowground productivity and soil
 aggregates for producing and protecting soil C and conserving soil N.
 Differences between switchgrass and native grasses also indicate a
 dependence on plant diversity. Soil C and N benefits of bioenergy crops
 depend strongly on root productivity and pre-establishment land use.
description: See the Materials and Methods of the associated publication for
 procedures on sampling and processing, and section 2.9 Statistical
 analysis for statistical models. The R software was used for all analyses
 (R Core Team, 2014); the R scripts are provided in the file
 Statistical_Analysis.R. R Core Team. (2014). R: A
 language and environment for statistical computing. R Foundation for
 Statistical Computing. http://www.Rproject.org/
description: # Data from: Long-term changes in soil carbon and nitrogen fractions in
 switchgrass, native grasses, and no-till corn bioenergy production systems
 These files contain data from soil and root samples use in this
 publication. The R script uses this data to perform the statistical
 analysis used in the publication. ## Description of the data and file
 structure The soil and root data contain measured variables within each
 experimental unit across multiple years during the study period. The
 variable in the R script called "top_level_directory" can be
 changed to the path of the download files' directory to run the
 analysis. Note that NA = not available. ## Code/Software There is an R
 script provided that conducts the statistical analysis used in this study.
 The necessary packages are listed at the top of the script. The variable
 in the script called "top_level_directory" can be changed to the
 path of the download files' directory to run the analysis.