I grew up in Springfield, Illinois before attending Grinnell College, where I earned a BA in Religious Studies. After graduation, I spent several years serving as an Americorps member, first with Habitat for Humanity and then with the Nevada Conservation Corps. I then began graduate school at North Dakota State University, where I received an MS in Natural Resources Management and a Ph.D. in Soil Science, where I focused on soil reclamation after oil development in the western North Dakota. I moved to Ames in 2018 to begin a postdoc with Jerry Hatfield at NLAE, and I transitioned into a Research Agronomist in August 2020. My research program will investigate a series of management practices, with a special focus on cover cropping and diversified rotations, to help develop resilient, highly productive cropping systems.

• Publications

  • (Clicking on the reprint icon will take you to the publication reprint.)
  • The LTAR Croplands Common Experiment at Upper Mississippi River Basin - Ames-(Peer Reviewed Journal)
    
    
  • Predicting spatiotemporal patterns of productivity and grazing from multispectral data using neural network analysis based on system complexity -(Peer Reviewed Journal)
    Ashworth, A.J., Avila, A., Smith, H., Winzeler, E., Owens, P.R., Flynn, K.C., O'Brien, P.L., Philipp, D., Su, J. 2024. Predicting spatiotemporal patterns of productivity and grazing from multispectral data using neural network analysis based on system complexity. Agrosystems, Geosciences & Environment. 7(3). Article e20571. https://doi.org/10.1002/agg2.20571.
    
  • Thermal time and precipitation dictate cereal rye shoot biomass production -(Peer Reviewed Journal)
    Crespo, C., O'Brien, P.L., Ruis, S.J., Kovar, J.L., Kaspar, T.C. 2024. Weather factors affecting cereal rye shoot biomass production and its implication on corn silage and soybean yields. Field Crops Research. 315. https://doi.org/10.1016/j.fcr.2024.109473.
    
  • Contrasting soil management systems had limited effects on soil health and crop yields in a North Central US Mollisol -(Peer Reviewed Journal)
    Crespo, C., O'Brien, P.L., Nunes, M.R., Ruis, S.J., Emmett, B.D., Rogovska, N.P., Malone, R.W., Cambardella, C., Kovar, J.L. 2024. Contrasting soil management systems had limited effects on soil health and crop yields in a North Central U.S. Mollisol. Soil Science Society of America Journal. https://doi.org/10.1002/saj2.20716.
    
  • Impact of conservation practices on nitrogen leaching in artificially drained Midwestern Mollisols-(Abstract Only)
    Rogovska, N.P., O'Brien, P.L., Malone, R.W., Emmett, B.D., Kovar, J.L., Jaynes, D., Kaspar, T., Moorman, T.B., Kyveryga, P. 2024. Impact of conservation practices on nitrogen leaching in artificially drained Midwestern Mollisols [abstract]. Soil and Water Conservation Society
    
  • Oil spill soil remediation using thermal desorption: project synthesis and outcomes -(Peer Reviewed Journal)
    O'Brien, P.L., DeSutter, T.M., Casey, F.X., Wick, A.F., Bartsch, Z.J., Croat, S.J., Struffert, S. 2024. Oil spill soil remediation using thermal desorption: project synthesis and outcomes. Agrosystems, Geosciences & Environment. 7(1). https://doi.org/10.1002/agg2.20463.
    
  • Winter camelina as an alternative cover crop for central Iowa corn-soybean systems-(Abstract Only)
    Kovar, J.L., O'Brien, P.L., Ruis, S.J., Emmett, B.D., Malone, R.W., Rogovska, N.P. 2023. Winter camelina as an alternative cover crop for central Iowa corn-soybean systems [abstract]. ASA-CSSA-SSSA Annual Meeting.
    
  • Temperate silvopastures have greater ecosystem services than conventional pasture systems -(Peer Reviewed Journal)
    Amorim, H., Ashworth, A.J., O'Brien, P.L., Thomas, A.L., Runkle, B., Philipp, D. 2023. Temperate silvopastures have greater ecosystem services than conventional pasture systems. Scientific Reports. 13. Article 18658. https://doi.org/10.1038/s41598-023-45960-0.
    
  • Nutrient leaching from an artificially drained Midwestern Mollisol across various conservation practices-(Abstract Only)
    Rogovska, N.P., Kovar, J.L., Malone, R.W., O'Brien, P.L., Emmett, B.D., Ruis, S.J. 2023. Nutrient leaching from an artificially drained Midwestern Mollisol across various conservation practices [abstract]. ASA-CSSA-SSSA Annual Meeting.
    
  • Long-term conservation practices reduce nitrate leaching while maintaining yields in tile-drained Midwestern soils -(Peer Reviewed Journal)
    Rogovska, N.P., O'Brien, P.L., Malone, R.W., Emmett, B.D., Kovar, J.L., Jaynes, D., Kaspar, T., Moorman, T., Kyveryga, P. 2023. Long-term conservation practices reduce nitrate leaching while maintaining yields in tile-drained Midwestern soils. Agricultural Water Management. 288. Article e108481. https://doi.org/10.1016/j.agwat.2023.108481.
    
  • Harvested winter rye energy cover crop: multiple benefits for North Central US -(Peer Reviewed Journal)
    Malone, R.W., Radke, A.G., Herbstritt, S., Wu, H., Qi, Z., Emmett, B.D., Helmers, M., Schulte, L., Feyereisen, G.W., O'Brien, P.L., Kovar, J.L., Rogovska, N.P., Kladivko, E.J., Thorp, K.R., Kaspar, T., Jaynes, D.B., Karlen, D., Richard, T. 2023. Harvested winter rye energy cover crop: multiple benefits for North Central US. Environmental Research Letters. 18(7). https://doi.org/10.1088/1748-9326/acd708.
    
  • Thirteen-year stover harvest and tillage effects on soil compaction in Iowa -(Peer Reviewed Journal)
    Phillips, C.L., Tekeste, M., Ebrahimi, E., Logsdon, S.D., Malone, R.W., O'Brien, P.L., Emmett, B.D., Karlen, D.L. 2023. Thirteen-year stover harvest and tillage effects on soil compaction in Iowa. Agrosystems, Geosciences & Environment. 6(2). Article e20361. https://doi.org/10.1002/agg2.20361.
    
  • Thirteen-year stover harvest and tillage effects on corn agroecosystem sustainability in Iowa -(Database / Dataset)
    Karlen, D.L., Phillips, C.L., O'Brien, P.L., Obrycki, J.N., Tekeste, M.Z., Ebrahimi, E., Cambardella, C.A., Kovar, J.L., Birrell, S.J. 2022. Thirteen-year stover harvest and tillage effects on corn agroecosystem sustainability in Iowa. Ag Data Commons. https://doi.org/10.15482/USDA.ADC/1528303.
    
  • Long-term conservation management practices improve water quality and maintain crop yields in the Upper Midwest-(Abstract Only)
    Rogovska, N.P., O'Brien, P.L., Malone, R.W., Emmett, B.D., Jaynes, D., Moorman, T.B., Kaspar, T., Parkin, T. 2022. Long-term conservation management practices improve water quality and maintain crop yields in the Upper Midwest. [abstract]. ASA-CSSA-SSSA Annual Meeting.
    
  • Rye as an energy cover crop: Management, forage quality, and revenue opportunities for feed and bioenergy -(Peer Reviewed Journal)
    Herbstritt, S., Richard, T.L., Lence, S.H., Wu, H., O'Brien, P.L., Emmett, B.D., Kaspar, T.C., Karlen, D.L., Kohler, K., Malone, R.W. 2022. Rye as an energy cover crop: Management, forage quality, and revenue opportunities for feed and bioenergy. Agriculture. 12(10). Article 12101691. https://doi.org/10.3390/agriculture12101691.
    
  • Spatiotemporal variability of saturated hydraulic conductivity evident across agricultural management strategies-(Abstract Only)
    O'Brien, P.L., Papanicolaou, A.N. 2022. Spatiotemporal variability of saturated hydraulic conductivity evident across agricultural management strategies [abstract]. American Geophysical Union.
    
  • Runoff and nutrient losses in extended and conventional crop rotations -(Peer Reviewed Journal)
    Logsdon, S.D., O'Brien, P.L. 2022. Runoff and nutrient losses in extended and conventional crop rotations. Agrosystems, Geosciences & Environment. 5(4). Article 20318. https://doi.org/10.1002/agg2.20318.
    
  • Nitrate losses in subsurface drainage and nitrous oxide emissions from a winter camelina relay cropping system reveal challenges to sustainable intensification -(Peer Reviewed Journal)
    Emmett, B.D., O'Brien, P.L., Malone, R.W., Rogovska, N.P., Kovar, J.L., Kohler, K., Kaspar, T.C., Moorman, T.B., Jaynes, D.B., Parkin, T.B. 2022. Nitrate losses in subsurface drainage and nitrous oxide emissions from a winter camelina relay cropping system reveal challenges to sustainable intensification. Agriculture, Ecosystems and Environment. 339. Article 108136. https://doi.org/10.1016/j.agee.2022.108136.
    
  • Nitrate losses and nitrous oxide emissions under contrasting tillage and cover crop management -(Peer Reviewed Journal)
    O'Brien, P.L., Emmett, B.D., Malone, R.W., Nunes, M.R., Kovar, J.L., Kaspar, T.C., Moorman, T.B., Jaynes, D.B., Parkin, T.B. 2022. Nitrate losses and nitrous oxide emissions under contrasting tillage and cover crop management. Journal of Environmental Quality. 51:683-695. https://doi.org/10.1002/jeq2.20361.
    
  • Rye-soybean double-crop: planting method and N fertilization effects in the North Central US -(Peer Reviewed Journal)
    Malone, R.W., O'Brien, P.L., Herbstritt, S., Emmett, B.D., Karlen, D.L., Kaspar, T.C., Kohler, K., Radke, A.G., Lence, S.H., Wu, H., Richard, T.L. 2022. Rye-soybean double-crop: planting method and N fertilization effects in the North Central US. Renewable Agriculture and Food Systems. 37(5):445-456. https://doi.org/10.1017/S1742170522000096.
    
  • Crop production response to conservation practices and sustainable intensification in a corn-soybean cropping system-(Abstract Only)
    O'Brien, P.L., Emmett, B.D., Kovar, J.L., Malone, R.W., Cambardella, C.A., Jaynes, D.B., Kaspar, T.C., Kohler, K.A., Moorman, T.B., Parkin, T.B. 2021. Crop production response to conservation practices and sustainable intensification in a corn-soybean cropping system [abstract]. ASA-CSSA-SSSA Annual Meeting. Paper no. 138076.
    
  • Multispecies cover crops in organic agricultural systems in the upper U.S. Midwest -(Peer Reviewed Journal)
    Logsdon, S.D., Cambardella, C.A., O'Brien, P.L. 2021. Multispecies cover crops in organic agricultural systems in the upper U.S. Midwest. Agrosystems, Geosciences & Environment. 4(4). Article e20221. https://doi.org/10.1002/agg2.20221.
    
  • Nitrogen losses in response to conservation practices and sustainable intensification of corn-soybean cropping systems in the Upper Midwest-(Abstract Only)
    Emmett, B.D., O'Brien, P.L., Malone, R.W., Kovar, J.L., Cambardella, C.A., Jaynes, D.B., Kaspar, T.C., Kohler, K.A., Moorman, T.B., Parkin, T.B. 2021. Nitrogen losses in response to conservation practices and sustainable intensification of corn-soybean cropping systems in the Upper Midwest [abstract]. Soil and Water Conservation Society Proceedings.
    
  • Short-term effects of nitrogen source on soil properties and plant growth -(Peer Reviewed Journal)
    Wacha, K.M., Hatfield, J.L., O'Brien, P.L., Dold, C. 2021. Short-term effects of nitrogen source on soil properties and plant growth. Agrosystems, Geosciences & Environment. 4(2). Article e20176. https://doi.org/10.1002/agg2.20176.
    
  • Agronomic approach to understanding climate change and food security -(Peer Reviewed Journal)
    O'Brien, P.L., Kral-O'Brien, K.C., Hatfield, J.L. 2021. Agronomic approach to understanding climate change and food security. Agronomy Journal. https://doi.org/10.1002/agj2.20693.
    
  • Quantifying the time-specific kinetic energy of simulated rainfall using a dynamic rain gauge system -(Peer Reviewed Journal)
    Wacha, K.M., Huang, C., O'Brien, P.L., Papanicolaou, T.N., Hatfield, J.L. 2021. Quantifying the time-specific kinetic energy of simulated rainfall using a dynamic rain gauge system. Agricultural & Environmental Letters. 6(1). Article e20042. https://doi.org/10.1002/ael2.20042.
    
  • Climate fluctuations and soil hydrology-(Book / Chapter)
    Hatfield, J.L., O'Brien, P.L., Wacha, K.M. 2022. Climate fluctuations and soil hydrology. In: Blanco, H., Kumar, S., Anderson, S.H., editors. Soil Hydrology in a Changing Climate. Clayton, Autralia: CSIRO Publishing. p.19-38.
    
  • Meta-analysis: Higher plant richness supports higher pollinator richness across many land use types -(Peer Reviewed Journal)
    Kral-O'Brien, K.C., O'Brien, P.L., Hovick, T.J., Harmon, J.P. 2021. Meta-analysis: Higher plant richness supports higher pollinator richness across many land use types. Annals of the Entomological Society of America. 114(2):267-275. https://doi.org/10.1093/aesa/saaa061.
    
  • CO2 fluxes and C budgets affected by stover harvest in Iowa continuous corn systems-(Abstract Only)
    O'Brien, P.L., Sauer, T.J., Archontoulis, S., Karlen, D.L., Laird, D.A. 2020. CO2 fluxes and C budgets affected by stover harvest in Iowa continuous corn systems [abstract]. ASA-CSSA-SSSA Annual Meeting. 128195.
    
  • Plant-to-plant biomass and yield variability in corn–soybean rotations under three tillage regimes -(Peer Reviewed Journal)
    O'Brien, P.L., Hatfield, J.L. 2021. Plant-to-plant biomass and yield variability in corn–soybean rotations under three tillage regimes. Agronomy Journal. 113(1):370-380. https://doi.org/10.1002/agj2.20514.
    
  • Integrating rangeland health and stream stability in assessments of rangeland watersheds -(Peer Reviewed Journal)
    Meehan, M.A., O'Brien, P.L., Hecker, G.A., Printz, J.L. 2021. Integrating rangeland health and stream stability in assessments of rangeland watersheds. Rangeland Ecology and Management. 75:104-111. https://doi.org/10.1016/j.rama.2020.12.005.
    
  • Soil health impacts on water and nutrient use efficiency -(Book / Chapter)
    Hatfield, J.L., O'Brien, P.L., Wacha, K.M. 2023. Soil health impacts on water and nutrient use efficiency. In: Bakhru A., editor. Nutrition and Integrative Medicine for Clinicians. Boca Raton, Florida. CRC press. p.279-286.
    
  • Corn stover harvest reduces soil CO2 fluxes but increases overall C losses -(Peer Reviewed Journal)
    O'Brien, P.L., Sauer, T.J., Archontoulis, S., Karlen, D.L., Laird, D. 2020. Corn stover harvest reduces soil CO2 fluxes but increases overall C losses. Global Change Biology Bioenergy. 12(11):894-909. https://doi.org/10.1111/gcbb.12742.
    
  • Influences of soil amendments on alfalfa production and soil properties -(Peer Reviewed Journal)
    DeSutter, T.M., Breker, M., Chatterjee, A., O'Brien, P.L., Wick, A. 2020. Influences of soil amendments on alfalfa production and soil properties. Forage and Grazinglands. 6:e20043. https://doi.org/10.1002/cft2.20043.
    
  • Phosphorus sorption and desorption in soils treated by thermal desorption -(Peer Reviewed Journal)
    Croat, S.J., DeSutter, T.M., Casey, F.X.M., O'Brien, P.L. 2020. Phosphorus sorption and desorption in soils treated by thermal desorption. Water, Air, and Soil Pollution. 231:216. https://doi.org/10.1007/s11270-020-04579-x.
    
  • Foliar nutrient concentrations of three economically important tree species in an alley-cropping system -(Peer Reviewed Journal)
    O'Brien, P.L., Thomas, A.L., Sauer, T.J., Brauer, D.K. 2020. Foliar nutrient concentrations of three economically important tree species in an alley-cropping system. Journal of Plant Nutrition. 43(17):2557-2568. https://doi.org/10.1080/01904167.2020.1783303.
    
  • Extreme soil surface temperatures reflect need to rethink agronomic management -(Peer Reviewed Journal)
    O'Brien, P.L., Hatfield, J.L. 2020. Extreme soil surface temperatures reflect need to rethink agronomic management. Agricultural & Environmental Letters. 5(1). https://doi.org/10.1002/ael2.20002.
    
  • Applications of vegetative indices from remote sensing to agriculture: past and future -(Peer Reviewed Journal)
    Hatfield, J.L., Prueger, J.H., Sauer, T.J., Dold, C., O'Brien, P.L., Wacha, K.M. 2019. Applications of vegetative indices from remote sensing to agriculture: past and future. Inventions. 4(4):71. https://doi.org/10.3390/inventions4040071.
    
  • Applications of vegetative indices from remote sensing to agriculture: past and future. -(Peer Reviewed Journal)
    Hatfield, J.L., Prueger, J.H., Sauer, T.J., Dold, C., O'Brien, P.L., Wacha, K.M. 2019. Applications of vegetative indices from remote sensing to agriculture: past and future. Inventions. 4(4):71. https://doi.org/10.3390/inventions4040071.
    
  • Cropping pattern changes diminish agroecosystem services in North and South Dakota, USA -(Peer Reviewed Journal)
    O'Brien, P.L., Hatfield, J.L., Dold, C., Kistner-Thomas, E.J., Wacha, K.M. 2020. Cropping pattern changes diminish agroecosystem services in North and South Dakota, USA. Agronomy Journal. 112(1):1-24. https://doi.org/10.1002/agj2.20001.
    
  • Using areal composition of riparian vegetation communities to identify thresholds in prairie streams -(Peer Reviewed Journal)
    Meehan, M.A., O'Brien, P.L. 2019. Using areal composition of riparian vegetation communities to identify thresholds in prairie streams. Rangeland Ecology and Management. 73(1):162-170. https://doi.org/10.1016/j.rama.2019.09.004.
    
  • Crop production on heavily disturbed soils following crude oil remediation -(Peer Reviewed Journal)
    Croat, S.J., O'Brien, P.L., Gasch, C.K., Casey, F.X., Desutter, T.M. 2020. Crop production on heavily disturbed soils following crude oil remediation. Agronomy Journal. 112:130-138. https://doi.org/10.1002/agj2.20077.
    
  • Need for false spring research in the Northern Great Plains, USA -(Peer Reviewed Journal)
    Kral-O'Brien, K., O'Brien, P.L., Harmon, J. 2019. Need for false spring research in the Northern Great Plains, USA. Agricultural and Environmental Letters. 4(1):190024. https://doi.org/10.2134/ael2019.07.0024.
    
  • Crop yield and nitrous oxide emissions following swine manure application: A meta-analysis -(Peer Reviewed Journal)
    Luo, W., O'Brien, P.L., Hatfield, J.L. 2019. Crop yield and nitrous oxide emissions following swine manure application: A meta-analysis. Agricultural & Environmental Letters. 4(1):190024. https://doi.org/10.2134/ael2019.07.0024.
    
  • Understanding the interactions of the food and agricultural system: The need for a systems approach-(Abstract Only)
    Hatfield, J.L., O'Brien, P.L., Dold, C., Kistner-Thomas, E.J., Wacha, K.M. 2019. Understanding the interactions of the food and agricultural system: The need for a systems approach. [Abstract] ASA-CSSA-SSSA Annual Meeting.
    
  • Dairy manure and synthetic fertilizer: A meta-analysis of crop production and environmental quality -(Peer Reviewed Journal)
    O'Brien, P.L., Hatfield, J.L. 2019. Dairy manure and synthetic fertilizer: A meta-analysis of crop production and environmental quality. Agrosystems, Geosciences & Environment. 2(1):1900027. https://doi.org/10.2134/age2019.04.0027.
    
  • Using the Rosgen Stream Classification System to aid in Riparian Complex Ecological Site Descriptions Development -(Peer Reviewed Journal)
    Meehan, M.A., O'Brien, P.L. 2019. Using the Rosgen Stream Classification System to aid in Riparian Complex Ecological Site Descriptions Development. Rangeland Ecology and Management. 72(5):729-735. https://doi.org/10.1016/j.rama.2019.05.001.
    

• Projects

  Managing Nutrient, Carbon, and Water Fluxes to Provide Sustainable and Resilient Cropping Systems for Midwestern Landscapes In-House Appropriated (D)   Accession Number:443545

  Novel Manure Management Technologies: Reducing Odors, Producing Slow-release Fertilizers, and Providing Ecosystem Services Non-Funded Cooperative Agreement (N)   Accession Number:441637

  Getting to the ROOT of the Corn Yield Drag Following Cover Crops: A Cereal Rye Residue Manipulation Experiment Reimbursable Cooperative Agreement (R)   Accession Number:444367

  Water and Light Use Efficiency of Native Grasses in a Silvopasture System Non-Assistance Cooperative Agreement (S)   Accession Number:443530

• ARS News Articles

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