Progress 10/01/15 to 09/30/19
Outputs
Target Audience:The target audience includes other scientists and land managers interested in Soil Organic Matter formation and Nitrogen Mineralization. These target audiencesreceiveinformation about this project from papers and presentations and students that are young scientists training in the PI's lab or taking his classes. Courses: The research conducted in this project is incorporated into NR 797, Environmental Soil Chemistry. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?Ph.D. students Amanda Daly, Andrea Jilling, Lauren Breza and Emily Kyker-Snowman and M.Sc. student Bennett Thompson all contributed to the project. All Grandy lab students attended national or international meetings in the past year where their current research was presented, and continue developing advanced approaches to understanding soil organic matter and nitrogen dynamics. The graduate students have been provided with teaching opportunities in my lab and classes, and all have participated in teaching classes and leading lab group meetings. Further, all have been given the opportunity to develop new collaborations with my colleagues. My lab has also provided multiple undergraduate students during this period with opportunities to participate in ongoing projects, and two of these students presented at undergraduate research conferences. How have the results been disseminated to communities of interest?This work was shared with the public in presentations to communities of scientists, journal articles, and two stakeholder conferences in New England. What do you plan to do during the next reporting period to accomplish the goals?
Nothing Reported
Impacts
What was accomplished under these goals?
Soil organic matter (SOM) influences most key soil processes including water holding capacity, soil aggregation, porosity, and erosion potential. Soil organic matter also influences several ecosystem-scale processes including trace gas emissions and net primary productivity and plays a central role in the global carbon cycle, although the processes underlying the formation of SOM remain poorly defined, as well as relationships between the soil carbon (C) and nitrogen (N) cycles. Further, the scientific community has lagged in its development of novel approaches to modeling SOM dynamics. Advances in microbial ecology provide new insights and approaches for incorporating greater realism into the way both soil biogeochemical C and N cycles are represented in models. In our work over the previous three years we have made four advances in these areas that are all relevant to our initial objectives. First, we have advanced understanding of the direct role microbes and their physiology play in the formation of SOM. We demonstrated that microbes can directly form complex, diverse and abundant SOM from the simplest of inputs. This work has transformed our understanding of how to manage with cover crops and other inputs the soil C cycle. Second, our work has advanced understanding of the pools and processes by which plants get N. We have shown the contrary to former paradigms that plants are able to extract nitrogen from the mineral or heavy fraction phase in soils. Demonstrating this provides entirely new avenues for plant-soil microbe interactions to provide N to plants. Third, we have advanced the explicit representation of microbes in soil biogeochemical models. The Microbial Mineral Carbon Stabilization Model (MIMICS) has been advanced in multiple papers and now also incorporates N. This model explicitly represents microbes and their physiology including C and N use efficiencies and growth rates which are now believed to be important parameters regulating both soil C and N but have not previously been incorporated into models. Finally, we address these issues and questions in the context of agroecosystem management, in particular, cover crops, and show that cropping system diversity is a primary tool at farmers' disposal for regulating soil biogeochemical functions in a changing world. Objective 1. Quantify the variation in microbial physiological traits driving SOM formation in organic and conventional agricultural soils. See previous annual reports. Objective 2. Develop and apply new laboratory methods for examining plant and microbial lipids in soil organic matter. See previous annual reports. Objective3. Ascertain how clay mineralogy influences the direction and size of nitrogen priming effects. See previous annual reports. Objective 4. Determine how microbial community composition and activity interact with clay content and type to control priming effects. Diversified crop rotations positively impact ecosystem processes in temperate agroecosystems by increasing yield resilience, crop productivity, and soil quality. Furthermore, diversified rotations require less nitrogen (N) fertilizer to achieve similar yields, and we are interested in how changes in soil N cycling could lead to a greater capacity of soil to supply N. We collected soil from a long-term diversity experiment at the Eastern Nebraska Research and Extension Center in Mead, NE. We conducted a novel, isotopic pool dilution assay that measures gross rates of amino acid production, consumption, and net rates of proteolysis. In addition, gross rates of N mineralization were measured along with microbial biomass, carbon use efficiency, respiration, enzyme activity, and total C and N. Crop rotation influences net rates of proteolysis for total amino acids but there was not a significant effect of fertilizer. Total amino acid consumption by microbes was approximately 1.5x greater than gross amino acid production, resulting in negative rates of net proteolysis between all treatments. Diverse rotations have higher net rates of proteolysis than corn-soy and continuous-corn rotations. Which together with other results suggests that agricultural management strategies play an important role in influencing bioavailable N cycling. Objective 5. Determine how clay texture and mineralogy control microbial priming of mineral-associated N. Particulate organic matter (POM) is considered an "active" source of nitrogen (N) in cultivated soils, responding readily to management and being more physically accessible to decomposers than mineral-associated forms of organic matter. However, there is increasing evidence that mineral-associated organic matter (MAOM) can also exhibit short-term changes to management that may influence nutrient cycling. In this study, we investigated how N within soil organic matter fractions responded to three years of tillage and cover crop treatments. Both particulate and fine fractions responded to tillage and cover crop treatments, but patterns varied by site and fraction. In the low-SOM MI and PA soils, ridge tillage and cover cropping both increased N within POM fractions. In contrast, at the IL site (high-SOM), the inclusion of cover crops led to higher N, specifically within the fine fractions (coarse silt and MAOM). Cover cropping increased MAOM N content in IL by 24%. When analyzing all sites together, variables associated with fine fractions were more closely associated with N mineralization and crop performance. MAOM can be responsive to short-term management practices and, along with POM, may also be potential sources of N for crops. Objective 6. Explicitly simulate microbial activity and physiology inMIcrobial-MIneral Carbon Stabilization model (MIMICS), and improve model predictions under changing environments. We created a new version of MIMICS with coupled C and nitrogen (N) cycling through litter, microbial, and soil organic matter (SOM) pools. The model was parameterized and validated against C and N data from the Long-Term Inter-site Decomposition Experiment Team. The model simulates C and N losses from litterbags in the LIDET study with reasonable accuracy that were comparable with simulations from the standard DAYCENT model that implicitly represents microbial activity. We also found that MIMICS-CN produces equilibrium values in line with measured values, showing that the model generates plausible estimates of ecosystem soil biogeochemical dynamics across continental-scale gradients. MIMICS-CN provides a platform for coupling C and N projections in a microbial-explicit model and exploring management effects on soil C and N.
Publications
- Type:
Journal Articles
Status:
Under Review
Year Published:
2019
Citation:
Bowles, T.M., M. Mooshammer, Y. Socolar, F. Calder�n, M.A. Cavigelli, S.W. Culman, W. Deen, C.F. Drury, A. Garcia y Garcia, A. Gaudin, W.S. Harkom, R.M. Lehman, S.L. Osborne, G.P. Robertson, J. Salerno, M.R. Schmer, J. Strock, and A.S. Grandy. Long-term evidence shows crop rotation diversification increases agricultural resilience to adverse climate conditions, In review.
- Type:
Journal Articles
Status:
Under Review
Year Published:
2019
Citation:
Kyker-Snowman, E., W.R. Wieder, S.D. Frey, and A.S. Grandy. Stoichiometrically coupled carbon and nitrogen cycling in the MIcrobial-MIneral Carbon Stabilization model (MIMICS-CN), In review.
- Type:
Journal Articles
Status:
Published
Year Published:
2019
Citation:
Wieder, W.R., D.M. Lawrence, R.A. Fisher, G.B. Bonan, S.J. Cheng, C.L. Goodale, A.S. Grandy, C.D. Koven, D.L. Lombardozzi, K.W. Oleson, and R.Q. Thomas. 2019. Beyond static benchmarking: Using experimental manipulations to evaluate land model assumptions. Global Biogeochemical Cycles. doi.org/10.1029/2018GB006141
- Type:
Journal Articles
Status:
Awaiting Publication
Year Published:
2019
Citation:
Jilling*, A., D. Kane, A. Williams, A. Yannarell, A. Davis, N. Jordan, R. Koide, D.A. Mortensen, R.G. Smith, S. Snapp, K. Spokas, and A.S. Grandy. Rapid and distinct responses of particulate and mineral-associated organic nitrogen to conservation tillage and cover crops. In press, Geoderma
- Type:
Journal Articles
Status:
Published
Year Published:
2019
Citation:
Schnecker J., T. Bowles, E.A. Hobbie, R.G. Smith, and A. Stuart Grandy. 2019. Substrate quality and concentration control decomposition and microbial strategies in a model soil system. Biogeochemistry 144:47-59 pp.
- Type:
Journal Articles
Status:
Published
Year Published:
2019
Citation:
Cates, A.M., M.D. Ruark, A.S. Grandy, R.D. Jackson. Small soil C cycle responses to three years of cover crops in maize cropping systems. In press, Agriculture, Ecosystems & Environment. 286:106649. https://doi.org/10.1016/j.agee.2019.106649
- Type:
Journal Articles
Status:
Published
Year Published:
2019
Citation:
Kallenbach, C.M., Matthew D. Wallenstein, Meagan E. Schipanski, A.S. Grandy. 2019. Managing agroecosystems for optimal soil microbial carbon use efficiency. Frontiers in Microbiology, 10:1146. doi: 10.3389/fmicb.2019.01146
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2019
Citation:
Invted. nd Microbial Bioavailable Nitrogen in Agroecosystems: Emerging Rhizosphere-Scale Concepts and Implications, ASA-CSSA-SSSA International annual Meeting, San Antonio, TX, 11/2019.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2019
Citation:
Invited. Potential priming mechanisms providing plants and microbes access to mineral-associated organic carbon and nitrogen, American Geophysical Union, Fall Meeting, Washington, DC. 12/2018.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2019
Citation:
Breza, C. L., Mooshammer M., Bowles, M.T., Jin L. V., Schmer, M., and Grandy, A. S. Crop Diversity Influences Gross Rates of Amino Acid Production and Nitrogen Mineralization. Ecological Society of America, Annual Meeting, Louisville, KY. August 11-16, 2019.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2019
Citation:
Mooshammer, M., &, Grandy, A. S., et. al. Response of Microbial Growth and Carbon Use Efficiency to Crop Rotational Diversity Across a Soil-Climate Gradient. Ecological Society of America, Annual Meeting, Louisville, KY. August 11-16, 2019.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2019
Citation:
Thompson, B. and Grandy, A. S. Microbial Community Control over Nitrogen Use Efficiency in Agroecosystems. Soil Science Society of America, Annual International Meeting, San Diego, CA. January 6-9, 2019.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2019
Citation:
Soil Organic Matter: How its made and why it matters for your agroecosystem, 2/2019, New Hampshire Farm to Forest, Concord, NH.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2018
Citation:
Soil Organic Matter: How its made and why it matters for your agroecosystem, 9/2018, New England Soil Health Meeting, organized by Maine Agricultural Experiment Station, Portsmouth, NH.
|
Progress 10/01/17 to 09/30/18
Outputs
Target Audience:The target audience includes other scientists and land managers receiving information about this project from papers and presentations and students that are young scientists training in the PI's lab or taking his classes. Courses:The research conducted in this project is incorporated into NR 797, Environmental Soil Chemistry. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?Postdoctoral scientist Emily Austin and Grandy Lab Ph.D. students Amanda Daly, Andrea Jilling, Lauren Breza, Emily Kyker-Snowman and M.Sc. student Bennett Thompson all contributed to the project. All Grandy lab students and postdocs have attended national or international meetings in the past year where their current research was presented, and continue developing advanced approaches to understanding soil organic matter and nitrogen dynamics. The postdoc and graduate students have been provided with teaching opportunities in my lab and classes, and all have participated in teaching classes and leading lab group meetings. Further, all have been given the opportunity to develop new collaborations with my colleagues. My lab has also provided seven undergraduate students during this period with opportunities to participate in ongoing projects, and two of these students presented at undergraduate research conferences. How have the results been disseminated to communities of interest?The work was shared with the scientific community in published conference presentations including multiple invited talks and six journal publications including Nature Sustainability. A highlight includes a keynote presentation to producers, industry, and scientists at the Soil Health Institute Annual Meeting, which was also recorded and has been viewed on Youtube more than 600 times, https://www.youtube.com/watch?v=-W4C1vte4eA What do you plan to do during the next reporting period to accomplish the goals?We will continue to train undergraduate and graduate students in the challenges related to understanding and managing the N cycle. We will carry out additional experiments to attempt to understand the role of different soil pools in providing plants and microbes nitrogen. In an effort to disseminate our results we will give to talks at scientific conferences and stakeholder meetings, as well as publish in top-tier journals. We will also leverage our Hatch funds to compete for additional external grants to advance the conceptual basis of the soil N cycle.
Impacts
What was accomplished under these goals?
Impact. Globally, humans add approximately three-fold more biologically available nitrogen (N) to terrestrial ecosystems than natural sources, primarily with synthetic fertilizers and legumes. This vast amount of N has substantially increased crop yields, but the majority of agricultural N inputs are not actually taken up by crops. Instead, much of this N is lost from agricultural fields, with wide-ranging impacts across local, regional, and global scales, including declines in water quality and biodiversity in terrestrial, aquatic, and marine ecosystems and increases in emissions of the greenhouse gas nitrous oxide (N2O). Losses of nitrogen from agriculture are thus major threats to environmental and human health at local, regional, and global scales. Emerging evidence shows that climate change and intensive agricultural management will interact to increase these harmful effects and undermine current mitigation efforts. Identifying effective mitigation strategies and supporting policies requires an integrated understanding of the processes underlying potential agricultural N responses to climate change. In an interdisciplinary review published this year, we describe these processes, propose a set of agroecological principles to guide research and policy for decreasing nitrogen losses in the future, and describe the economic factors that could constrain or enable their implementation. Second, we published a conceptual framework to challenge current assumptions about N mineralization, a key source of N in all soils. N mineralization involves the conversion of organic to plant-available inorganic N. Existing concepts ignores the role of microbial communities in N mineralization. We show that microbial communities and their physiology are strong controls over N mineralization and this N availability. This work could ultimately lead to managing soils to foster more N efficient microbial communities that deliver N to plants when they need it most. Objective 1. Quantify the variation in microbial physiological traits driving soil organic matter (SOM) formation in organic and conventional agricultural soils. This objective was completed and reported on in a previous report. Objective 2. Develop and apply new laboratory methods for examining plant and microbial lipids in soil organic matter. We changed directions on this objective and instead focused on the development of new laboratory methods for amino acid gross flux dynamics. This is a novel method that we are the first lab in the U.S. to optimize, advancing our dual objectives of better understanding SOM dynamics and N cycling. Objective 3. Ascertain how clay mineralogy influences the direction and size of nitrogen priming effects. This objective was completed and reported on in a previous report. Objective 4. Determine how microbial community composition and activity interact with clay content and type to control priming effects. This objective was completed and reported on in a previous report. Objective 5. Determine how clay texture and mineralogy control microbial priming of mineral-associated N. We have been conducting experiments to determine how plant root exudates, microbial communities, and clay minerals interact to control soil nitrogen availability. We examine a commonly overlooked but potentially important source of nitrogen: organic matter bound to clay particles. Although generally considered inaccessible to plants, we explore how plant root exudates drive the microbial and non-biological release of nitrogen from clay associations.To test this hypothesis, we conducted laboratory incubation in which we applied exudate-like compounds to soils composed of only sand and physically-isolated,mineral-associated organic matter (MAOM). The use of stable isotopically-enriched carbon additions allowed me to detect the proportion of CO2 respired that was derived from externally-applied carbon or from the soil organic matter. Carbon additions stimulated microbial activity, extracellular enzyme production, and the subsequent breakdown of MAOM-derived carbon and nitrogen. We found C additions stimulated CO2 respiration and MAOM degradation. Compared to the control, glucose and oxalic acid-treated soils respired 139% and 89% more C, respectively. In both cases, we also observed a net positive priming effect indicating that microbes were releasing C from MAOM at a faster rate than in the control. The magnitude of this priming effect was significant: increases of 200-400% in glucose treatments and up to 280% in oxalic acid treatments. Likewise, C treatments stimulated C/N-acquiring and oxidative enzyme activities, although the response was specific to the substrate. Glucose additions specifically enhanced the production of an exo-cellulase and a chitinase, while oxalic acid suppressed most N-acquiring enzyme activities and enhanced peroxidase and phenoloxidase activities. Finally, gross ammonium production was positively associated with the priming of MAOM-C. Our results indicate that common root exudates, like glucose and oxalic acid, can significantly increase the turnover and potential release of C and N from MAOM. This work continues in the work that we propose here. Objective 6. Explicitly simulate microbial activity and physiology inMIcrobial-MIneral Carbon Stabilization model (MIMICS), and improve model predictions under changing environments. Here, we used our newly developed MIMICS C model with coupled N cycles and data synthesis to examine how climate-change driven alterations in precipitation patterns are likely to affect N cycling and losses in agricultural landscapes and to highlight promising interventions to minimize environmental N losses while maintaining or increasing productivity. As a case study, we consider the Central U.S., a globally-important agricultural production region for cereal (maize and wheat) and soybean production. We review climate projections for the region and then highlight key water-N linkages and the vulnerability of N to environmental loss and incorporate these findings into models. Our modeling efforts show the importance of system-wide solutions (e.g. the use of cover crops) to address N losses from agroecosystems (Bowles*, T.M., Atallah, S.S., Campbell, E.A., Gaudin, A.C.M., Wieder, W.R. and A.S. Grandy. 2018. Agricultural nitrogen losses in a changing climate: Processes, predictions, and agroecological solutions, Nature Sustainability, 1:399-408. Featured in USDA NIFA Blog. https://nifa.usda.gov/blog/unh-recommendations-seek-help-farmers-curb-agricultural-nitrogen-losses).
Publications
- Type:
Journal Articles
Status:
Published
Year Published:
2018
Citation:
Rothstein, D.R., Toosi, E.R., Schaetzl, R.J., and A.S. Grandy. 2018. Direct delivery of carbon from surface organic horizons to the subsoil in coarse-textured Spodosols: Implications for deep soil C dynamics, Soil Science Society of America Journal, 82:969-982.
- Type:
Journal Articles
Status:
Published
Year Published:
2018
Citation:
Lombardozzi, D.L., G. B. Bonan, W. Wieder, A. S. Grandy, C. Morris, and D. L. Lawrence. Cover crops may cause winter warming in snow-covered regions. Journal of Geophysical Research Letters, 45: 9889-9897. Featured in Science Daily https://www.sciencedaily.com/releases/2018/12/181219093855.htm and multiple other online reports including European Scientist.
- Type:
Journal Articles
Status:
Published
Year Published:
2018
Citation:
Siders, A.C., Z.G. Compson, B.A. Hungate, P. Dijkstra, G.W. Koch, A.S. Wymore, A.S. Grandy, J.C. Marks. 2018. Litter identity affects assimilation of carbon and nitrogen by a shredding caddisfly, Ecosphere, 9(7):e02340, doi.org/10.1002/ecs2.2340
- Type:
Journal Articles
Status:
Published
Year Published:
2018
Citation:
Whalen, E.D., R.G. Smith, A.S. Grandy, and S.D. Frey. 2018. Manganese limitation as a mechanism for reduced decomposition in soils under atmospheric nitrogen deposition. Soil Biology & Biochemistry,127:252-263
- Type:
Journal Articles
Status:
Published
Year Published:
2018
Citation:
Jilling, A., Contosta, A.R., Frey, S., Scimel, J., Schnecker, J., Smith, R.G., Tiemann, L., and A.S. Grandy. Minerals in the rhizosphere: overlooked mediators of soil nitrogen availability to plants and microbes, Biogeochemistry, doi:10.1007/s10533-018-0459-5
- Type:
Journal Articles
Status:
Published
Year Published:
2018
Citation:
Bailey, V.L., B.B. Lamberty, K. DeAngelis, A.S. Grandy, C.V. Hawkes, K. Heckman, K. Lajtha, R.P. Phillips, B.N. Sulman, K.E.O. Todd-Brown, and M.D. Wallenstein. 2017. Soil carbon cycling proxies: understanding their critical role in understanding climate change feedbacks, Global Change Biology, doi:10.1111/gcb.13926
- Type:
Journal Articles
Status:
Published
Year Published:
2017
Citation:
Melillo, J.M., S.D. Frey, K.M. DeAngelis, W.J. Werner, M.J. Bernard, F.P. Bowles, G. Pold, M.A. Knorr, A.S. Grandy. 2017. Long-term Pattern and magnitude of soil carbon feedback to the climate system in a warming world., Science, 358:101-105
- Type:
Conference Papers and Presentations
Status:
Other
Year Published:
2017
Citation:
Bowles, T. M., Grandy, A. S., et. al. Crop Rotation Diversity and Yield Resilience: Evidence from 11 Long-Term Experiments in North America Across a Precipitation Gradient. Soil Science Society of America, Annual Meeting, Tampa, FL. October 22-25, 2017.
- Type:
Conference Papers and Presentations
Status:
Other
Year Published:
2017
Citation:
DeAngelis, K., &, Grandy, A. S. et. al. Mechanisms of Microbial Destabilization of Soil C Shifts Over Decades of Warming. American Geophysical Union, Fall Meeting, New Orleans, LA. December 11-15, 2017.
- Type:
Conference Papers and Presentations
Status:
Other
Year Published:
2017
Citation:
Kyker-Snowman, E., Wieder, W. R., and Grandy, A. S. Different Mechanisms of Soil Microbial Response to Global Change Result in Different Outcomes in the MIMICS-CN Model. American Geophysical Union, Fall Meeting, New Orleans, LA. December 11-15, 2017.
- Type:
Conference Papers and Presentations
Status:
Other
Year Published:
2017
Citation:
Jilling, A., Grandy, A. S., and Keiluweit, M. The Potential Bioavailability of Mineral-Associated Organic Nitrogen in the Rhizosphere. American Geophysical Union, Fall Meeting, New Orleans, LA. December 11-15, 2017.
- Type:
Journal Articles
Status:
Published
Year Published:
2018
Citation:
Bowles, T.M., Atallah, S.S., Campbell, E.A., Gaudin, A.C.M., Wieder, W.R. and A.S. Grandy. 2018. Agricultural nitrogen losses in a changing climate: Processes, predictions, and agroecological solutions, Nature Sustainability, 1:399-408. Featured in USDA NIFA Blog. https://nifa.usda.gov/blog/unh-recommendations-seek-help-farmers-curb-agricultural-nitrogen-losses
- Type:
Other
Status:
Other
Year Published:
2018
Citation:
Breza, L., &.., Grandy, A.S. Soil management practices, not stoichiometric needs, drives microbial activity in agriculture soils. UNH Graduate Research Conference. Durham, NH. April 1, 2018.
- Type:
Conference Papers and Presentations
Status:
Other
Year Published:
2018
Citation:
Jilling, A. and Grandy, A.S. 3 Clay minerals: Overlooked purveyors of soil nitrogen. Ecological Society of America, Fall Meeting, New Orleans, LA. August 5-10, 2018
- Type:
Conference Papers and Presentations
Status:
Other
Year Published:
2018
Citation:
Jilling, A., Keiluweit, M., and A.S. Grandy. Priming mechanisms providing plants and microbes access to mineral-associated organic nitrogen. Ecological Society of America Conference, New Orleans, LA, August 5-10, 2018
- Type:
Conference Papers and Presentations
Status:
Other
Year Published:
2018
Citation:
Keynote: Microbial Physiology Regulates How Much Soil Organic Matter becomes Crop Residue. Soil Health Institute Annual Meeting, Albuquerque, NM, 8/2018.
|
Progress 10/01/16 to 09/30/17
Outputs
Target Audience:The target audience includes other scientists and land managers receiving information about this project from papers and presentations and students that are young scientists training in the PI's lab or taking his classes. Courses. The research conducted in this project is incorporated into NR 797, Environmental Soil Chemistry; and also NR 795, Soil Fertility and the Environment. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?Postdoctoral scientists Emily Austin, Tim Bowles, and Joerg Schnecker, and Grandy Lab Ph.D. students Amanda Daly, Andrea Jilling, Lauren Breza, Emily Kyker-Snowman and M.Sc. student Bennett Thompson all contributed to the project. All Grandy lab students and postdocs have attended national or international meetings in the past year where their current research was presented, and continue developing advanced approaches to understanding soil organic matter and nitrogen dynamics. The postdocs and graduate students have been provided with teaching opportunities in my lab and classes, and all have participated in teaching classes and leading lab group meetings. Further, all have been given the opportunity to develop new collaborations with my colleagues. My lab has also provided seven undergraduate students during this period with opportunities to participate in ongoing projects, and two of these students presented at undergraduate research conferences. How have the results been disseminated to communities of interest?The work was shared with the scientific community in 5 published conference presentations and several journal publications. We gave multiple presentations to the scientific community, which included 12 invited talks at national/international conferences or universities. What do you plan to do during the next reporting period to accomplish the goals?To address the role of clays and priming in Soil Organic Matter (SOM) dynamics, we will continue to examine whether mineral-associated organic matter is accessible to microbes and ultimately to plants? Do soluble rhizodeposits enable microbes to access mineral-bound nitrogen through directly desorbing/liberating mineral-bound compounds? Through stimulating microbes that are more adept at interfering with sorptive interactions (i.e. targeted enzyme production)? Or through stimulating microbial activity to a point of N-starvation and N-desperation? Along with answering these questions, we are also examining with field and lab experiments how does management (tillage and cover cropping) impact the chemical composition of clay-associated SOM and/or dominant binding mechanisms? How do these impacts influence the N-priming capacity and the N-priming response more generally? We continue to also work on the nitrogen cycle and incorporate it into models. We are fine-tuning a new nitrogen mineralization technique, based upon depolymerization by isotope pool dilution of 15N-labeled amino acids coupled with analysis by Gas Chromatography quantitative Mass Spectrometry (GCqMS), and nitrogen mineralization (nitrification and ammonification, as well as N immobilization) by isotope pool dilution of 15N labeled NH4+ or NO3-. The quantification of protein depolymerization using amino acid pool dilution and GC-qMS is a recently developed method, which in the last year has been undergoing improvement and optimization in Grandy's lab at UNH under the direction of a postdoc who helped develop the original method. We have also begun and will continue incorporating nitrogen into MIcrobial-MIneral Carbon Stabilization Model MIMICS. ?
Impacts
What was accomplished under these goals?
Impact. Nitrogen availability often limits agricultural yields. Modern intensive agricultural systems are productive due to fertilizer nitrogen? N inputs but N inefficient, resulting in environmental N losses that degrade water quality and increase atmospheric nitrous oxide (N2O) concentrations. Climate change is projected to worsen these environmental N losses by altering precipitation patterns and temperature. Common practices to reduce N losses from agricultural systems focus on reducing fertilization with only limited success, while largely ignoring the provisioning of N by internal, microbial-driven processes. Despite this, agricultural plants typically get more than half of their N from internal sources and microbial processes rather than fertilizers. This year we developed new conceptual models and experiments to explore the simple but challenging question: from where and how do plants get their nitrogen? First, we have developed a robust series of conceptual models arguing that a previously 'hidden' pool of nitrogen is a major supplier of plant N. This pool is mineral-associated organic matter (MAOM), a potentially large and rich reservoir for N in soils. MAOM N is currently considered largely unavailable to plants due to the physicochemical forces on mineral surfaces that stabilize organic matter. We argue that in hotspots around roots, MAOM an important source of nitrogen for plants. Several biochemical strategies enable plants and microbes to compete with mineral-organic interactions and effectively access MAOM. Working together, plant breeders, soil scientists and microbial ecologists will find ways to develop cropping systems whereby the plants can access this large N pool on demand, reducing need for fertilizer N. Second, we have developed conceptual frameworks and experiments to challenge current assumptions about N mineralization, a key source of N in all soils. N mineralization involves the conversion of organic to plant-available inorganic N. Existing concepts ignore the role of microbial communities in N mineralization. We are accumulating evidence that microbial communities and their physiology are strong controls over N mineralization and this N availability. This work could ultimately lead to managing soils to foster more N efficient microbial communities that deliver N to plants when they need it most. Objective 1. Quantify the variation in microbial physiological traits driving SOM formation in organic and conventional agricultural soils. This objective was completed and reported on in theprevious report. Objective 2. Develop and apply new laboratory methods for examining plant and microbial lipids in soil organic matter. Work on this objective has not begun. Objective 3. Ascertain how clay mineralogy influences the direction and size of nitrogen priming effects. We have developed a conceptual model that outlines how clays and clay mineralogy influence the priming of soil N. We synthesized exiting literature and emerging evidence and developed new conceptual models from both the ecological and biogeoscience communities to argue that while depolymerization is a critical first step, clay minerals may be an important and overlooked mediator of bioavailable N, and especially in the soil rhizosphere where they are both a large source and sink for N. Mineral-associated organic matter (MAOM) is a rich reservoir for N in soils and can hold up to 20x more N than particulate fractions. MAOM fractions also preferentially accumulate N compounds such as proteins, amino acids, and nucleic acids. While some MAOM is protected from degradation, other MAOM can be mobilized by plants, microbes, and their interactions, leading to substantial amounts of MAOM-derived N in the soil solution. (Jilling, A., Keiluweit, M., Contosta, A.R., Frey, S., Schimel, J., Schnecker, J., Smith, R., Tiemann, L., Grandy, A.S. (Accepted with revisions). Minerals in the rhizosphere: overlooked mediators of soil nitrogen bioavailability. Biogeochemistry) Objective 4. Determine how microbial community composition and activity interact with clay content and type to control priming effects. Our literature synthesis and conceptual model development now pointthe way forward for how microbial communities interact with clays to influence the biovailability of N. The availability of N to plants is partly regulated by root-associated microbes and their access to and utilization of soil nutrients. As such, specific properties of rhizosphere microbes, such as composition, abundance, and physiology, may mediate the magnitude or direction of the priming effect and the amount of MAOM destabilized via priming. For example, we show the C and N use efficiency (CUE, NUE) of the microbial community coupled with its cellular stoichiometry will determine nutrient demand. As microbial CUE increases, N demand and NUE also increase to maintain cellular C/N ratios. With increasing N demand as microbial CUE and NUE increase, the microbial N-mining response to root exudation should also increase. That is, as root exudates provide a labile C source and microbial C needs are satisfied, microbes will invest more in enzymes to acquire N from MAOM. In contrast, microbes that use C inefficiently will require less N, and will show a depressed N mining response to root exudation. Further, microbial CUE and NUE also constrain microbial community size, turnover, and activity, which will have feedbacks to the cycling and bioavailability of MAOM N. (Jilling, A., Keiluweit, M., Contosta, A.R., Frey, S., Schimel, J., Schnecker, J., Smith, R., Tiemann, L., Grandy, A.S. (Accepted with revisions). Minerals in the rhizosphere: overlooked mediators of soil nitrogen bioavailability. Biogeochemistry) Objective 5. Determine how clay texture and mineralogy control microbial priming of mineral-associated N. We have been conducting been conducting experiments to determine how plant root exudates, microbial communities, and clay minerals interact to control soil nitrogen availability. W examine a commonly overlooked but potentially important source of nitrogen: organic matter bound to clay particles. Although generally considered inaccessible to plants, we explore how plant root exudates drive the microbial and non-biological release of nitrogen from clay associations. To test this hypothesis, we conducted laboratory incubation in which we applied exudate-like compounds to soils composed of only sand and physically-isolated MAOM. The use of stable isotopically-enriched carbon additions allowed me to detect the proportion of CO2 respired that was derived from externally-applied carbon or from the soil organic matter. Carbon additions stimulated microbial activity, extracellular enzyme production, and the subsequent breakdown of MAOM-derived carbon and nitrogen. In follow-up experiments, we will test a wider array of soil types to assess how differences in clay composition and microbial community mediate the soil's response to carbon additions. Objective 6. Explicitly simulate microbial activity and physiology in MIcrobial-MIneral Carbon Stabilization model (MIMICS), and improve model predictions under changing environments. Here, used our newly developed MIMICS C model with coupled N cycles and data synthesis to examine how climate-change driven alterations in precipitation patterns are likely to affect N cycling and losses in agricultural landscapes and to highlight promising interventions to minimize environmental N losses while maintaining or increasing productivity. We review climate projections for Midwest U.S. region and then highlight key water-N linkages and the vulnerability of N to environmental loss. Finally, we show that conventional, fertilizer-use-efficiency-based approaches are insufficient to mitigate N losses now, and will likely be even less effective under climate change scenarios.
Publications
- Type:
Journal Articles
Status:
Published
Year Published:
2017
Citation:
Bailey, V.L., B.B. Lamberty, K. DeAngelis, A.S. Grandy, C.V. Hawkes, K. Heckman, K. Lajtha, R.P. Phillips, B.N. Sulman, K.E.O. Todd-Brown, and M.D. Wallenstein. 2017. Soil carbon cycling proxies: understanding their critical role in understanding climate change feedbacks, Global Change Biology, 10.1111/gcb.13926
- Type:
Journal Articles
Status:
Published
Year Published:
2017
Citation:
Melillo, J.M., S.D. Frey, K.M. DeAngelis, W.J. Werner, M.J. Bernard, F.P. Bowles, G. Pold, M.A. Knorr, A.S. Grandy. 2017. Long-term Pattern and magnitude of soil carbon feedback to the climate system in a warming world., Science, 358:101-105
- Type:
Journal Articles
Status:
Published
Year Published:
2017
Citation:
Austin, E., K. Wickings, M. McDaniel, G.P. Robertson, and A.S. Grandy. 2017. Cover crop root contributions to soil carbon in a no-till corn bioenergy cropping system, Global Change Biology-Bioenergy, 9:1252-1263.
- Type:
Journal Articles
Status:
Published
Year Published:
2017
Citation:
Buchkowski, R.W., M.A. Bradford, A. S. Grandy, O.J. Schmitz, and W.R. Wieder. 2017. Applying population ecology theory to advance understanding of belowground biogeochemistry, Ecology Letters, 20:231-245.
- Type:
Journal Articles
Status:
Published
Year Published:
2017
Citation:
Pold, G., A.S. Grandy, J.M. Melillo, and K.M. DeAngelis. 2017. Changes in substrate availability drive carbon cycle response to chronic warming. Soil Biology and Biochemistry, 110:68-78.
- Type:
Conference Papers and Presentations
Status:
Other
Year Published:
2017
Citation:
Invited Keynote Presentation. Revising Paradigms of Nitrogen Mineralization and Availability in Agroecosystems. Soil Ecology Society, Annual Meeting, Fort Collins, CO. June 5-9, 2017
- Type:
Conference Papers and Presentations
Status:
Other
Year Published:
2017
Citation:
Invited Conference Panel: Soil Health Research Directions (3 participants including Kate Scow). Soil Ecology Society, Annual Meeting, Fort Collins, CO. June 5-9, 2017
Yes
- Type:
Conference Papers and Presentations
Status:
Other
Year Published:
2017
Citation:
Invited. Scaling soil organic matter with microbial physiology, University of Adelaide, Adelaide, Australia, 04/2017
- Type:
Conference Papers and Presentations
Status:
Other
Year Published:
2017
Citation:
Invited. Scaling soil organic matter with microbial physiology, University of Western Sydney, Australia, 04/2017
- Type:
Conference Papers and Presentations
Status:
Accepted
Year Published:
2017
Citation:
Invited. Soil minerals: a hidden source of rhizosphere nitrogen mediates plant-microbe competition, University of Waikato, Auckland, NZ, 3/2017
- Type:
Conference Papers and Presentations
Status:
Other
Year Published:
2016
Citation:
Invited. Soil minerals: an overlooked mediator of plant-microbe competition for organic N in the rhizosphere. American Geophysical Union Fall Meeting, San Francisco, CA, 12/2016
- Type:
Conference Papers and Presentations
Status:
Other
Year Published:
2017
Citation:
Grandy, A. S., Jilling, A., and Keiluweit, M. Soil Minerals in the Rhizosphere: A Hidden Source of Nitrogen and Mediator of Plant Microbe Competition. Ecological Society of America, Annual meeting, Portland, OR. August 6-11, 2017.
- Type:
Conference Papers and Presentations
Status:
Other
Year Published:
2017
Citation:
Castle, S., Song, Z, Grandy, A. S. and Kinkel, L. Does Climate Warming Alter Plant Diversity-Soil Carbon Relationships and Associated Soil Microbial Communities? Soil Ecology Society, Annual Meeting, Fort Collins, CO. June 5-9, 2017.
- Type:
Conference Papers and Presentations
Status:
Other
Year Published:
2017
Citation:
ONeil, B., &, Grandy, A. S., et. al. Linking Soil C and N Cycling and Trace Gas Flues with soil Bacterial Communities Along a Gradient of Simple to Complex Crop Rotations. Soil Ecology Society, Annual Meeting, Fort Collins, CO. June 5-9, 2017.
- Type:
Conference Papers and Presentations
Status:
Other
Year Published:
2017
Citation:
Daly, A., Richter, A. and Grandy, A. S. Influence of Wet-Dry Cycles and Organic Management on Gross Nitrogen Depolymerization in Agricultural Soils. Soil Ecology Society, Annual Meeting, Fort Collins, CO. June 5-9, 2017
- Type:
Conference Papers and Presentations
Status:
Other
Year Published:
2016
Citation:
Tiemann, L. K., A. S. Grandy and J. Hartter. Connections between Soil Fertility Declines, Land Use, Ethnicity, Education, and Wealth in Uganda. American Geophysical Union, Annual Meeting, San Francisco, CA. December 12-16, 2016.
- Type:
Conference Papers and Presentations
Status:
Other
Year Published:
2016
Citation:
Kallenbach, C. M., Fierer, N., Frey, S. D., and A.S. Grandy. Mineralogy impacts microbial community establishment and early microbial-SOM formation. American Geophysical Union Conference, San Francisco, CA, 12/2016
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Progress 10/01/15 to 09/30/16
Outputs
Target Audience:The target audience includes other scientists and land managers receiving information about this project from papers and presentations and students that are early career scientists training in the PI's lab or taking his classes. The research conducted in this project is incorporated into NR 797, Environmental Soil Chemistry, as well as a new couse, Soil Fertility and the Environment. My lab's work was featured in a Grain News article titled, 'Building up the soil in your fields: Changing your crop rotation and management can change the content of your soil'. It was also featured in an article in De Standaard, Belgium's largest newspaper. I was also an invited speaker at a regional cover crop conference for scientists and practitioners (~200 people)in Maryland. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided? Postdoctoral scientists Emily Austin, Tim Bowles,and Joerg Schnecker, and Ph.D. students Amanda Daly, Andrea Jilling, Lauren Breza,Emily Kyker-Snowman (Grandy lab PhD students) and Igor Alexandre (visiting student from Brazil for one year) and Grace Pold (visiting student from UMass Amherst for two weeks) have all participated on this project. All Grandy lab students and postdocs have attendednational or international meetings in the past year where their current research was presented, and continue developing advanced approaches to understanding soil organic matter and nitrogen dynamics. The postdocs and graduate students have been provided with teaching opportunities in my lab and classes, and all have participated in teaching classes and leading lab group meetings. Further, all have been given the opportunity to develop new collaborations with my colleagues. My lab has also provided seven undergraduate students during this period with opportunities to participate in ongoing projects. How have the results been disseminated to communities of interest?The work was shared with the scientific community in34 published papers, including an article in Nature Communications, and two additional in press at Ecology Letters and Global Change Biology - Bioenergy. We gave 15 presentations to the scientific community, which included5 invited talks at conferences or universities. We also gavean outreach presentations to stakeholder groups in Maryland on cover crops, and were featured in several popular press publications. What do you plan to do during the next reporting period to accomplish the goals?To address the role of clays and priming in SOM dynamics, we will continue to examine whether mineral-associated organic matter is accessible to microbes?.Do soluble rhizodeposits enable microbes to accessmineral-bound nitrogen- Through directly desorbing/liberating mineral-bound compounds? Through stimulating microbes that are more adept at interfering with sorptive interactions (i.e. targeted enzyme production)? Or through stimulating microbial activity to a point of N-starvation and N-desperation? Along with answering these questions, we are also examining with field and lab experiments howdoes management (tillage and cover cropping) impact the chemical composition of clay-associated SOM and/or dominant binding mechanisms? How do these impacts influence the N-priming capacity and the N-priming response more generally? We continue to also work on the nitrogen cycle and incorporate it into models. We are fine tuning a new nitrogen mineralization technique, based upon depolymerization by isotope pool dilution of 15N-labeled amino acids coupled with analysis by GC-qMS, and nitrogen mineralization (nitrification and ammonification, as well as N immobilization) by isotope pool dilution of 15N-labeled NH4+ or NO3-. The quantification of protein depolymerization using amino acid pool dilution and GC-qMS is a recently developed method, which in the last year has been undergoing development and optimization in Grandy's lab at UNH under the direction of a postdoc who helped develop the original method. We have also begun and will continue incorporating nitrogen into MIMICS.
Impacts
What was accomplished under these goals?
Impact. The loss of soil organic matter from agricultural soils has severe local regional, and global consequences. Soil organic matter is intricately linked with soil health, drives nitrogen and other nutrient cycling and plant productivity, and contains twice as much carbon as the atmosphere. Restoring soil organic matter in agricultural systems is thus an essential component of sustainability, but the processes by which this is done remain uncertain. We continue to seek an understanding of where and how soil organic matter is formed, and how these processes are influenced by management. Scientists have generally considered that the best way to build soil organic matter was to slow down or inhibit decomposition using plants that soil microbes find difficult to decompose. The idea is that the undecomposed plant parts would gradually become soil organic matter, especially if the soil microbial community was inactive. However, in a recent Nature Communications paper we show that soil organic matter accumulates from inputs of dead microbial cells and microbial byproducts formed when microbes eat plant roots and residues, rather than from the plants themselves. This has been challenging for scientists to prove because once soil organic matter is formed, identifying whether it was most recently a plant or microbial cell is impossible. Soil organic matter accumulation is greatest when more-not less-active microbial biomass is formed. This is especially true when that biomass is produced more efficiently, meaning more of the substrate is converted to biomass rather than carbon dioxide. Challenging another long-held view, we also show that the characteristics of the microbial community are even more important for soil organic matter formation than soil type. The new research provides promise for designing agricultural systems that promote microbial communities that optimize soil organic matter formation. Applying these concepts, much of the historical research in agricultural systems has focused on tillage, but its effects on soil organic matter are inconsistent, and no-till cropping systems do not always build soil organic matter. We have focused on an alternative approach to restoring soil organic matter - increasing agricultural crop diversity. We continued to use principles from biodiversity-ecosystem function theory to test whether changes in plant diversity over time (e.g., through crop rotation) affect soil communities and function in an agroecosystem. Using field and lab experiments, we show that as crop diversity increases, distinctive soil microbial communities are related to increases in soil aggregation,organic carbon and total nitrogen stocks, microbial activity, accelerated rates of nutrient cycling, and the ratio of carbon to nitrogen acquiring enzyme activities. By increasing the quantity, quality and complexity of crop residues, high diversity rotations can sustain soil biological communities, with positive effects on soil organic matter accrual, soil fertility, and crop yield. Objective 1. Quantify the variation in microbial physiological traits driving Soil Organic Matter (SOM) formation in organic and conventional agricultural soils. Completed and published last reporting period, (Kallenbach, C.M.*, A.S. Grandy, S.D. Frey, and A. F. Diefendorf. Microbial physiology and necromass regulate agricultural soil carbon accumulation. 2015. Soil Biology & Biochemistry (SBB), 9:279-290 - research featured in Our Changing Planet, US Global change Research Program annual report to Congress; Top-ranked SBB paper for social media; top-ten most downloaded paper) Objective 2. Develop and apply new laboratory methods for examining plant and microbial lipids in soil organic matter. This objective has not yet begun. Objective3. Ascertain how clay mineralogy influences the direction and size of nitrogen priming effects. Objective 4. Determine how microbial community composition and activity interact with clay content and type to control priming effects. Objective 5. Determine how clay texture and mineralogy control microbial priming of mineral-associated N. Our first effort to tackle these objectives has been the development of a new conceptual framework. Recent research on the rate-limiting steps in soil nitrogen (N) availability has shifted in focus from mineralization to soil organic matter (SOM) depolymerization. To that end, Schimel and Bennett (2004) argued that together with enzymatic breakdown of polymers to monomers, microsite processes and plant-microbial competition collectively drive N cycling. Here weare developingnew conceptual models arguing that while depolymerization is a critical first step, mineral-organic associations may ultimately regulate the provisioning of bioavailable organic N, especially in the rhizosphere. Mineral-associated organic matter (MAOM) is a rich reservoir for N in soils and often holds 5-7x more N than particulate or labile fractions. However, MAOM is considered largely unavailable to plants as a source of N due to the physicochemical forces on mineral surfaces that stabilize organic matter. We argue that in rhizosphere hotspots, MAOM is in fact, a potentially mineralizable and important source of nitrogen for plants. In experimental work, we collected soils from an ongoing experiment replicated across four growing sites in north central and mid-Atlantic United States. Soils were subject to different tillage and cover crop treatments, representing a gradient from intensive to more conservation-oriented systems. Combining both sonication and wet-sieving techniques, we fractionated bulk soils into four distinct components: free Particulate Organic Matter (fPOM), occluded POM (oPOM), a coarse silt fraction, and fine silt and clay-organic matter (MAOM). We measured the weight of recovered fractions and measured the C and N content of each.Our results reveal that management significantly influenced N and C distribution across SOM fractions, however, the response was context-specific. Responses to management were not consistent between sites, possibly highlighting divergent processes underlying SOM transformation and transfer across pools at different sites. Collectively, the above work is challenging our understanding of where and how plants obtain their nitrogen and will suggest new approaches to better synchronize plant N needs and soil N availability in agricultural systems. Objective 6. Explicitly simulate microbial activity and physiology inMIcrobial-MIneral Carbon Stabilization model (MIMICS), and improve model predictions under changing environments. First, we considered the theoretical implications of introducing theory from population ecology into MIMICS and other microbial-explicit soil biogeochemistry models (Buchkowski, R.W., M.A. Bradford, A. S. Grandy, O.J. Schmitz, and W.R. Wieder. 2017 Applying population ecology theory to advance understanding of belowground biogeochemistry, Ecology Letters, 20: 231-245). Second, we developed, parameterized, and validated a coupled C and N version of MIMICS. This model accomplishes the following: Represents microbial-explicit soil C and N cycling through litter, microbial, and stabilized soil organic matter (SOM) pools; Simulates C and N losses from litterbags in the Long-Term Intersite Decomposition Experiment Team (LIDET) dataset with reasonable accuracy; 3) Performs better than existing soil models in simulating C and N losses from LIDET litterbags. These advances are now incorporated into a manuscript to be submitted in 2017. Collectively this work is improving our representation of microbial processes in models and simultaneously improving predictions of global biogeochemical processes and their response to human activities.
Publications
- Type:
Journal Articles
Status:
Published
Year Published:
2016
Citation:
Kallenbach, C.M., S.D. Frey and A.S. Grandy. Direct evidence for microbial-derived soil organic matter formation and its ecophysiological controls, Nature Communications, 7:13630
- Type:
Journal Articles
Status:
Published
Year Published:
2017
Citation:
Buchkowski, R.W., M.A. Bradford, A. S. Grandy, O.J. Schmitz, and W.R. Wieder.2017 Applying population ecology theory to advance understanding of belowground biogeochemistry, Ecology Letters, 20: 231-245 DOI: 10.1111/ele.12712
- Type:
Journal Articles
Status:
Published
Year Published:
2017
Citation:
Austin, E., K. Wickings, M. McDaniel, G.P. Robertson, and A.S. Grandy, Cover crop root contributions to soil carbon in a no-till corn bioenergy cropping system, Global Change Biology-Bioenergy, DOI: 10.1111/gcbb.12428
- Type:
Journal Articles
Status:
Published
Year Published:
2016
Citation:
Grandy, A.S., W.R. Wieder, K. Wickings, and E. Kyker-Snowman. 2016 Beyond microbes: Are fauna the next frontier in soil biogeochemical models? Soil Biology and Biochemistry, 102:40-44
- Type:
Journal Articles
Status:
Published
Year Published:
2016
Citation:
McDaniel, M.D. and A.S. Grandy. 2016. Soil microbial biomass and function are altered by 12 years of crop rotation. SOIL, 2:583-599.
- Type:
Journal Articles
Status:
Published
Year Published:
2016
Citation:
Hurisso, T.T. S.W. Culman, W.R. Horwath, J. Wade, D. Cass, J.W. Beniston, T.M. Bowles, A.S. Grandy, A.J. Franzluebbers, M.E. Schipanski, Lucas, C. Ugarte. 2016. Comparison of permanganate oxidizable C and mineralizable C for assessment of organic matter stabilization and mineralization, Soil Science Society of America Journal, 80:1352-1364
- Type:
Journal Articles
Status:
Published
Year Published:
2016
Citation:
McDaniel, M.D., A.S. Grandy, L.K. Tiemann, and M.N. Weintraub. 2016. Eleven years of crop diversification alters decomposition dynamics of litter mixtures, Ecosphere, 7:1-18
- Type:
Journal Articles
Status:
Published
Year Published:
2016
Citation:
Castle, S.C., D.R. Nemergut, A.S. Grandy, J.W. Leff, E.B. Graham, E. Hood, S.K. Schmidt, K. Wickings, C.C. Cleveland. 2016. Successional processes drive convergence of microbial communities, Soil Biology and Biochemistry, Soil Biology and Biochemistry, 101, 74-84.
- Type:
Journal Articles
Status:
Published
Year Published:
2016
Citation:
Geyer, K.M., E. Kyker-Snowman, A.S. Grandy, and S.D. Frey. Microbial efficiency: Accounting for physiological, ecological, and time-dependent controls over the fate of metabolized organic matter, Biogeochemistry,127:173-188
- Type:
Journal Articles
Status:
Published
Year Published:
2016
Citation:
Rinkes, Z.L., I. Bertrand, B.H.Z. Amin, A.S. Grandy, K. Wickings, and M.N. Weintraub. Nitrogen alters microbial enzyme dynamics but not lignin chemistry during maize decomposition, Biogeochemistry, 128:171-186
- Type:
Journal Articles
Status:
Published
Year Published:
2016
Citation:
Williams, A., A.S. Davis, P.M. Ewing, M. Li, Y. Lou, A.S. Davis, A.S. Grandy, D.A. Kane, R.T. Koide, D.A. Mortensen, R.G. Smith, S.S. Snapp, K.A. Spokas, A.C. Yannerell, N.R. Jordan. Precision management of soil nitrogen via functional zone management. Agriculture, Ecosystems & Environment, 231: 291-295
- Type:
Journal Articles
Status:
Published
Year Published:
2016
Citation:
Williams, A., D.A. Kane, P.M. Ewing, L.W. Atwood, A. Jilling, M. Li, Y. Lou, A.S. Davis, A.S. Grandy, S.C. Huerd, M.C. Hunter, R.T. Koide, D.A. Mortensen, R.G. Smith, S.S. Snapp, K.A. Spokas, A.C. Yannarell, and N.R. Jordan. Soil functional zone management: a vehicle for enhancing production and soil ecosystem services in row-crop agroecosystems, Frontiers in Plant Science, 7:65.
- Type:
Journal Articles
Status:
Published
Year Published:
2016
Citation:
Wickings, K.W., A.S. Grandy, and A.N. Kravchenko. 2016. Going with the flow: landscape position drives differences in microbial biomass and activity in conventional, low input, and organic agricultural systems in the Midwestern U.S., Agriculture Ecosystems and Environment, 218:1-10
- Type:
Journal Articles
Status:
Published
Year Published:
2016
Citation:
Diem, J.E., J. Hartter, J.D. Salerno, E. McIntyre, and A.S. Grandy. 2016. Comparison of measured multi-decadal rainfall variability with farmers perceptions of and responses to seasonal changes in western Uganda, Regional Environmental Change, DOI:10.1007/s10113-016-0943-1.
- Type:
Conference Papers and Presentations
Status:
Other
Year Published:
2016
Citation:
Soil minerals: an overlooked mediator of plant-microbe competition for organic N in the rhizosphere. American Geophysical Union Fall Meeting, San Francisco, CA, 12/2016
- Type:
Conference Papers and Presentations
Status:
Other
Year Published:
2016
Citation:
Microbial-driven soil organic matter formation, Cornell University Biogeochemistry Seminar Series, Ithaca, NY, 10/16.
- Type:
Other
Status:
Other
Year Published:
2016
Citation:
Crop Biodiversity: The key to improving Soil Ecosystem Function, Colorado State University, Fort Collins, CO, 06/2016.
- Type:
Other
Status:
Other
Year Published:
2016
Citation:
Scaling Soil Organic Matter Dynamics, Colorado State University Fort Collins, CO, 06/2016.
- Type:
Journal Articles
Status:
Published
Year Published:
2016
Citation:
Williams, A., A.S. Davis, A. Jilling. A.S. Grandy, R.T. Koide, D.A. Mortensen, R.G. Smith, S.S. Snapp, K.A. Spokas, A.C. Yannerell, N.R. Jordan. 2016. Reconcing opposing soil processes in row-crop agroecosystems via soil functional zone management. Agriculture, Ecosystems & Environment, 236:99-107.
- Type:
Conference Papers and Presentations
Status:
Other
Year Published:
2016
Citation:
Tiemann, L. K., A. S. Grandy and J. Hartter. Connections between Soil Fertility Declines, Land Use, Ethnicity, Education, and Wealth in Uganda. American Geophysical Union, Annual Meeting, San Francisco, CA. December 12-16, 2016.
- Type:
Conference Papers and Presentations
Status:
Other
Year Published:
2016
Citation:
Kallenbach, C. M., Fierer, N., Frey, S. D., and A.S. Grandy. Mineralogy impacts microbial community establishment and early microbial-SOM formation. American Geophysical Union Conference, San Francisco, CA, 12/2016
- Type:
Conference Papers and Presentations
Status:
Other
Year Published:
2016
Citation:
Bowles, T.M., and Grandy, A.S. Addressing agricultural nitrogen losses in a changing climate. Soil Science Society of America Annual Meeting, Phoenix, AZ. 11/2016
- Type:
Conference Papers and Presentations
Status:
Other
Year Published:
2016
Citation:
Schnecker ,J, and A.S. Grandy. Microbial foraging strategy is dependent on substrate concentration. SOMmic Microbial Contribution and Impact in Soil Organic Matter, Structure and Genesis Workshop, Leipzig, Germany, 11/2016
- Type:
Conference Papers and Presentations
Status:
Other
Year Published:
2016
Citation:
Jilling, A. and A.S. Grandy. Clay minerals: Critical mediators of nitrogen availability in the rhizosphere. SOMMIC Workshop: Microbial Contribution and Impact on Soil Organic Matter, Structure, and Genesis, Leipzig, Germany, 11/2016.
- Type:
Conference Papers and Presentations
Status:
Other
Year Published:
2016
Citation:
Schnecker, J., A. S. Grandy, D.B. Meeden, F. Calderon, M. Cavigelli, M. Lehman, and L. Tieman. Does crop rotational diversity increase soil microbial resistance and resilience to drought and flooding? Ecological Society of America Annual Meeting, Fort Lauderdale, Fl, 08/2016
- Type:
Conference Papers and Presentations
Status:
Other
Year Published:
2016
Citation:
Schnecker,J, and A.S. Grandy. Soil organic matter content: a non-liner control on microbial respiration in soils. European Geoscience Union General Assembly, Vienna, Austria, 04/2016
- Type:
Conference Papers and Presentations
Status:
Other
Year Published:
2016
Citation:
Grandy, A.S. Temporal plant diversity and intensification drives microbial communities and soil carbon dynamics in agricultural systems. Soil Ecology Society Biennial Meeting, Colorado Springs, CO, 06/2015
- Type:
Conference Papers and Presentations
Status:
Other
Year Published:
2016
Citation:
Jilling, A. and A.S. Grandy. Nitrogen distribution across organic matter fractions varies with soil type and management. Graduate Research Conference, University of New Hampshire, 4/2016.
- Type:
Conference Papers and Presentations
Status:
Other
Year Published:
2016
Citation:
Austin, EE, Wickings, K, McDaniel M, Robertson, PG, Grandy, AS. 2016. The fate of cover crop root and shoot carbon belowground in a corn bioenergy system. American Geophysical Union annual fall meeting, San Francisco, CA.
- Type:
Conference Papers and Presentations
Status:
Other
Year Published:
2016
Citation:
Daly, A.B., A.S. Grandy. How agricultural management shapes soil microbial communities: patterns emerging from genetic and genomic studies. European Geological Union Annual Meeting, Vienna, Austria, 04/2016
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