@article{roper_osmond_heitman_2024, title={Wheat cover crop has minimal effect on physical soil properties in the North Carolina Piedmont}, volume={7}, ISSN={["1435-0645"]}, DOI={10.1002/agj2.21634}, abstractNote={Abstract Environmental awareness about soil and water conservation in agroecosystems has shifted behaviors toward favoring conservation practices in agricultural management. Interest in conservation tillage and cover cropping has increased, but some regions encounter major challenges with adjusting management to accommodate these practices while optimizing crop production. In an Ultisol in the North Carolina Piedmont, a long‐term corn ( Zea mays ) and soybean ( Glycine max ) rotation with tillage intensities ranging from no‐till to moldboard plowing in a randomized complete block design was used to assess changes in physical soil properties after introducing wheat ( Triticum aestivum ) as a winter cover crop. Cover crop biomass was measured along with volumetric water content (VWC) and bulk density (BD) at 0–15 cm, water retention (WR), water‐stable aggregation (WSA), and soil organic carbon (SOC) at 0–7.5 cm, and penetration resistance (PR) at 0–45 cm. No differences in VWC or WR could be solely attributed to cover cropping, but no‐till with cover cropping had the highest macroporosity where there was no vehicle traffic. Vehicle traffic had a stronger effect on soil compaction (BD and PR) than cover cropping regardless of tillage. Conservation tillage increased WSA and SOC when compared to plow tillage, but three seasons of a wheat cover crop did not significantly change these properties, possibly because wheat produced low biomass each year (750–1900 kg ha −1 ). Wheat had minimal effect on physical soil properties in the short term, and potential for improvement with long‐term optimal cover crop management in this region requires further assessment.}, journal={AGRONOMY JOURNAL}, author={Roper, Wayne R. and Osmond, Deanna L. and Heitman, Joshua L.}, year={2024}, month={Jul} }
 @article{wade_culman_gasch_lazcano_maltais-landry_margenot_martin_potter_roper_ruark_et al._2022, title={Rigorous, empirical, and quantitative: a proposed pipeline for soil health assessments}, volume={170}, ISSN={["1879-3428"]}, DOI={10.1016/j.soilbio.2022.108710}, abstractNote={Soil health is a promising lens through which to approach land management, having the potential to serve as a descriptor of biophysical processes and as an effective communication tool across stakeholders. However, this potential has been largely unrealized due to difficulty in quantitatively assessing soil health and linking those assessments to outcomes. Here we discuss many multiple persistent obstacles to quantitative soil health assessment and outline a suite of analyses to help address those obstacles. Specifically, we propose a quantitative approach to developing and selecting soil health indicators that help connect management-induced changes in soil health to specific outcomes (e.g., yield or water quality). To demonstrate the utility of this approach, we perform a small case study using published data from North Carolina and New York cropping systems. Additionally, we outline how this approach is scalable and flexible enough to integrate future soil health metric development. The proposed approach stands to provide a quantitative, empirical basis for future measurement, assessment, and interpretation of soil health. • Robust and reliable quantitative soil health assessment has proved elusive. • Our pipeline addresses persistent pitfalls of current soil health assessment. • Indicator selection and connecting to agroecological outcomes are essential. • We outline an approach to soil health assessment that is rigorous and interpretable.}, journal={SOIL BIOLOGY & BIOCHEMISTRY}, author={Wade, Jordon and Culman, Steve W. and Gasch, Caley K. and Lazcano, Cristina and Maltais-Landry, Gabriel and Margenot, Andrew J. and Martin, Tvisha K. and Potter, Teal S. and Roper, Wayne R. and Ruark, Matthew D. and et al.}, year={2022}, month={Jul} }
 @article{roper_osmond_heitman_2019, title={A Response to "Reanalysis Validates Soil Health Indicator Sensitivity and Correlation with Long-term Crop Yields"}, volume={83}, ISSN={["1435-0661"]}, DOI={10.2136/sssaj2019.06.0198}, abstractNote={We published data showing that current soil health indicator (SHI) assessments do not consistently detect differences in a range of soil management practices implemented in North Carolina soils. Van Es and Karlen reanalyzed our data and asserted that it validates SHI correlation to crop yields and sensitivity to management as measured by the Comprehensive Assessment of Soil Health (CASH). We respond to van Es and Karlen with a more representative analysis of our data showing that individual SHI measurements are not predictive of crop yield from the 30‐yr North Carolina agronomic trial. Regressions for aggregate stability (r2 = 0.07) and P (r2 = 0.18) show that neither SHI sufficiently predicts corn yield for this dataset and show no obvious pattern based on tillage intensity. Relationships between corn (Zea mays L.) yield and most biological SHI had r2 ≤ 0.18, with only soil protein being moderately predictive of corn yield (r2 = 0.45). The CASH index to assess overall soil health by integrating physical, chemical, and biological SHI measurements into a single value of soil health is also not predictive of corn yield in the trial (r2 = 0.12). It is possible that current sampling and analytical procedures for assessing soil health do not consistently detect differences in productivity from soils with regional differences in land and ecological resources. We believe that calibrating SHI assessments to quantifiable agroecological outcomes instead of statistical rankings will reduce bias across regions and create a more inclusive framework for quantifying soil health.}, number={6}, journal={SOIL SCIENCE SOCIETY OF AMERICA JOURNAL}, author={Roper, Wayne R. and Osmond, Deanna L. and Heitman, Joshua L.}, year={2019}, pages={1842–1845} }
 @article{roper_robarge_osmond_heitman_2019, title={Comparing Four Methods of Measuring Soil Organic Matter in North Carolina Soils}, volume={83}, ISSN={["1435-0661"]}, DOI={10.2136/sssaj2018.03.0105}, abstractNote={
Core Ideas
Results of agronomic management effects on SOM are inconsistent among methods.
Correlations among methods of measuring SOM differ depending on soil.
Soil organic matter content should be compared using similar procedures.
Soil organic matter (SOM) provides many beneficial soil ecosystem services for sustainable soil management, but it is unclear how results from different methods of measuring SOM should be compared when making soil management decisions. To compare different methods, we used 84 soil samples from long‐term agronomic trials in the coastal plain, piedmont, and mountain regions of North Carolina. Coastal plain and mountain trials included combinations of tillage and management (conventional vs. organic), whereas piedmont trials were configured to evaluate tillage intensity. The methods used to measure SOM were Walkley‐Black (WB), mass loss on ignition (LOI), automated dry combustion (ADC), and humic matter (HM) colorimetry. Correlations among LOI, WB, and ADC were significant (p < 0.0001) for SOM measured from the total population of soils, but variability due to location implied that HM had no correlation to other methods. For measures of soil organic carbon compared to SOM, the WB results were biased high compared to ADC, and ADC was more strongly correlated to LOI than WB. When using the methods to evaluate the effects of agronomic management on SOM, results varied for different methods and locations. Conservation management did not consistently accumulate more SOM than other soil management practices, and no method consistently differentiated soils based on management. Variation in the composition of SOM measured using conventional methods may be causing discrepancies in reported changes in SOM content over time. To avoid confusion about how agronomic management affects SOM, assessments should limit comparisons to methodologies with similar measurement protocols.}, number={2}, journal={SOIL SCIENCE SOCIETY OF AMERICA JOURNAL}, author={Roper, Wayne R. and Robarge, Wayne P. and Osmond, Deanna L. and Heitman, Joshua L.}, year={2019}, pages={466–474} }
 @article{roper_osmond_heitman_wagger_reberg-horton_2017, title={Soil Health Indicators Do Not Differentiate among Agronomic Management Systems in North Carolina Soils}, volume={81}, ISSN={["1435-0661"]}, DOI={10.2136/sssaj2016.12.0400}, abstractNote={Recent soil tests evaluating “soil health” on a broad scale may not properly consider the intrinsic limitations of soil properties, and have not been assessed in regionally unique soil conditions. To evaluate three soil tests in North Carolina, we used long-term agronomic management trials from three distinct physiographic regions: mountain (22 yr), piedmont (32 yr), and coastal plain (17 yr). Mountain and coastal plain trials included combinations of organic or chemical management with or without tillage; the piedmont trial included nine different tillage treatments. Soil samples were collected and submitted for analysis as recommended by the North Carolina Department of Agriculture and Consumer Services, Haney soil health test (HSHT), and Cornell comprehensive assessment of soil health (CASH). Plant nutrient concentrations varied but were still sufficient for crops. The CASH physical soil indicators, such as surface hardness and aggregate stability, were not statistically different, regardless of tillage intensity or management. Biological soil indicators (e.g., CO₂ respiration) responded differently to management, but this differentiation was inconsistent among locations and tests. Despite many years of conservation management, the CASH results described mountain soils as “low” or “very low” soil health for all but no-till organic management, which received a “medium” score. The HSHT results considered soil from all but moldboard plowing (piedmont) to be in good health. Finally, there was no correlation between soil health tests and crop yields from North Carolina soils. Soil health tests should be calibrated to better differentiate among soil management effects that vary depending on intrinsic soil limitations.}, number={4}, journal={SOIL SCIENCE SOCIETY OF AMERICA JOURNAL}, author={Roper, Wayne R. and Osmond, Deanna L. and Heitman, Joshua L. and Wagger, Michael G. and Reberg-Horton, S. Chris}, year={2017}, pages={828–843} }