Fates of Soil Carbon and Nitrogen in Agricultural and Bioenergy Crop Systems

FATES OF SOIL CARBON AND NITROGEN IN AGRICULTURAL AND BIOENERGY CROP SYSTEMS

Sponsoring Institution

National Institute of Food and Agriculture

Project Status

COMPLETE

Funding Source

HATCH

Reporting Frequency

Annual

Accession No.

1003346

Grant No.

(N/A)

Cumulative Award Amt.

(N/A)

Proposal No.

(N/A)

Multistate No.

(N/A)

Project Start Date

Nov 19, 2014

Project End Date

Jun 30, 2019

Grant Year

(N/A)

Program Code

[(N/A)]- (N/A)

Project Director
Kemanian, AR, R.

Recipient Organization
PENNSYLVANIA STATE UNIVERSITY
208 MUELLER LABORATORY
UNIVERSITY PARK,PA 16802

Performing Department
Plant Science

Non Technical Summary
Achieving a balance between sustainable, economically viable, agriculture and the preservation of clean air, clean water, and healthy ecosystems is a grand environmental challenge for the 21st century. This balance is especially difficult to achieve with the nitrogen (N) and carbon (C) cycles. Agriculture is an important driver of changes in regional nitrogen cycles because inorganic nitrogen fertilizers and legume cultivation are integral high yielding crop production. Society is increasingly looking to agricultural ecosystems to mitigate changes in the global C cycle by storing more carbon in soils and expanding production of bioenergy crops with low global warming potential. The overall goal of this project is to increase our understanding of the fates of C and N in agricultural and bioenergy cropping systems of Pennsylvania and surrounding states. Our specific goals are to: 1) evaluate the potential to replace synthetic N fertilizer with biological N fixation by soil microorganisms and cover crops, 2) improve computer simulation models to provide new tools for soil fertility testing and N fertilizer recommendations, and 3) evaluate whether expansion of bioenergy crops in the region could provide a fuel with low global warming potential.To meet these goals we will monitor existing and establish new field experiments at the Penn State research station and on private farms. We are comparing nitrogen losses from corn-soybean-wheat rotations with no cover crop, with monoculture cover crops, and with polyculture cover crop mixtures. Our hypothesis is that the high diversity cover crop mixtures provide more ecosystem services than monocultures. We are monitoring C and N cycles in willow, switchgrass, miscanthus, and biodiverse conservation grasslands to determine which bioenergy cropping systems may have low global warming potential. In some of these experiments we assess greenhouse gas emissions from different portions of the landscape (e.g. well drained slopes vs excessively wet valley bottom positions) to determine how the placement of bioenergy crops on marginal land may affect emissions. We are coupling a new type of soil fertility testing (the CO2 burst method) with a computer simulation model to develop a new tool for farmers seeking N fertilizer recommendations on lands with high cover crop N inputs. Finally, we are quantifying how microorganisms (cyanobacteria) growing on the surface of the soil affect soil quality and N inputs to the ecosystem.

Animal Health Component

75%

Research Effort Categories

Basic

25%

Applied

75%

Developmental

(N/A)

Classification

Knowledge Area (KA)	Subject of Investigation (SOI)	Field of Science (FOS)	Percent
102	0199	1070	30%
101	0199	1103	30%
112	0320	1070	30%
102	0199	2000	10%

Knowledge Area
102 - Soil, Plant, Water, Nutrient Relationships; 112 - Watershed Protection and Management; 101 - Appraisal of Soil Resources;

Subject Of Investigation
0320 - Watersheds; 0199 - Soil and land, general;

Field Of Science
1103 - Other microbiology; 1070 - Ecology; 2000 - Chemistry;

Keywords

Goals / Objectives
The overall goal of this project is to increase our understanding of the fates of C and N in agricultural and bioenergy cropping systems of Pennsylvania and surrounding states with comparable climate and soils. Over the next five years our specific goals are to: 1) evaluate the potential for N fixation by cyanobacteria and cover crops to improve (i.e. reduce pollution outputs) the N and C balance of agroecosystems; 2) improve simulation models that couple C and N to simulate ecosystem dynamics and provide new tools for soil fertility testing and N fertilizer recommendations; and 3) advance the lifecycle analysis of C and N in perennial grass and willow bioenergy crops in the northeast. Objectives:1. Evaluate how cover crops and the diversity of planted cover crops contribute to multiple ecosystem services related to the C and N cycles. Ecosystem services to be evaluated include reducing N leaching losses, potential for cover crop N fixation to supply N to cash crops, reducing soil erosion, increasing soil C storage.2. Improve simulation models that couple C and N to simulate ecosystem dynamics and provide new tools for soil fertility testing and N fertilizer recommendations. This will include parameterizing effects of soil properties, weatherconditions, fertilization, and crop management for models of soil C and N cycling.3. Advance the lifecycle analysis of C and N in perennial grass and willow bioenergy crops in the northeast. This will include monitoring field plots for N and C cycles including soil to atmosphere greenhouse gas emissions.4. Measure amounts and fates of carbon and nitrogen fixed by soil surface biofilms, including 1) temporal and spatial patterns of naturally occurring cyanobacterial growth and N2 fixation farms, 2) gas fluxes from replicated plots treated with cyanobacteria and varying levels of fertilizer, and 3) 15N2 incorporation by inoculated field soils in laboratory using petri dish microcosms.

Project Methods
Objective 1. We will monitor existing and new field experiments at the Russell E. Larson Experimental farm. Current experiments contrast monoculture cover crops with mixtures that include up to 9 species of cover crops. Our hypothesis is that polycultures provide more ecosystem services than cover crop monocultures. We are implementing operational scale fully replicated experimental designs. To assess N fixation by the cover crops we monitor the biomass of cover crops prior to termination. To quantify the effects of cover crops on N supply to cash crops, we monitor soil inorganic N biweekly following cover crop termination and the yield and nutrient concentrations of cash crops. To monitor N leaching, we bury ion exchange resins below the prominent rooting zone of plants and monitor N leaching through the soil profile. In a subset of our plots we also measure N leaching with bucket lysimeters. Finally, we have been using estimates of organic matter, particulate organic matter, and total soil C to detect impacts of cover crops on soil C pools.Objective 2. We continue to develop Cycles, a biogeochemical model with coupled C and N cycles. Over the next 5 years we will develop the potential for Cycles to be used as a tool to predict fertilizer requirements for cash crops. We expect the model to improve predictions of fertilizer requirements because it can better take into account mineralization of soil organic matter, manure, and cover crop residue N. We will evaluate whether a new type of soil fertility testing, the flush of CO2 from an air dried soil (Haney et al. 2001), can be incorporated into into a process-based modeling framework. The framework and the model can be used to interpret and predict site-specific responses of multiple crop species under diverse climate scenarios. Process-based models are used extensively to simulate the complex interactions among plant growth and yield, C and N cycling, environmental conditions, soil properties, and management practices (Williams, 1990; McCown et al., 1996). Most agro-ecological models simulate C and N cycling using discrete pools or compartments with transfers of matter among pools occurring at each time-step. Transfer rates depend on decomposition rates and transfer efficiencies. Efficiency is defined as the fraction of C lost from a pool that can be effectively transferred to another pool other than CO2. Carbon and N cycling in models are linked through stoichiometry of each compartment and efficiency of C transfer between compartments.The flush of CO2 also links C and N cycling through empirical relationships between CO2 evolution and N mineralization. Since the flush of CO2 has biological significance we propose that C and N cycling sub-routines of agro-ecological models integrate the flush of CO2 conceptually and quantitatively. We hypothesize that doing so will improve the ability of the model to simulate N availability from SOM and help interpret and apply outcomes of field experiments. The model of choice as a starting point is Cycles, a model derived from C-Farm (Kemanian and Stockle, 2010) and closely related to CropSyst (Stockle et al., 2003) in the water and crop growth modules. Estimating the flush of CO2 from 1-3 d incubation is straightforward, requiring only temperature, assuming optimum soil moisture, soil organic C and N, fresh residue C and N, and mineral N availability. This information will be collected in experiments and will allow a detailed characterization of model departure from measured fluxes.Objective 3. We have established field experiments comparing willow cultivars to each other on Penn State research land, and perennial grasses (switchgrass and miscanthus) to each other on Penn State land and on private farms. In the willow experiments we are using eddy covariance to monitor carbon exchange between the bioenergy ecosystems and the environment. In the switchgrass and miscanthus ecosystems we are focusing on changes in water flow and greenhouse gas emissions. In collaboration with the USDA ARS we have established replicated plots that compare conservation reserve grasslands, switchgrass, and miscanthus. We will intensively monitor volumetric soil moisture content at multiple depths in the soil and at multiple landscape positions. The site includes a fragipan that can perch water, so our landscape position sampling takes this feature into account. The landscape positions are midslope where no perched water table exists, lower on the slope where water can become perched above the fragipan but only occasionally, and at the toe sloe, where perched water tables are a common feature. Collocated with these soil moisture sensors are measurements of soil N2O fluxes. With this research we will evaluate the role of water flow paths in determining the N2O fluxes from perennial grass bioenergy crops.Objective 4. Surface soils in selected areas of Penn State's Agronomy Farm will be sampled year-round, focusing on areas with histories of recurrent biofilm growth. Analysis of natural abundance N isotope composition will provide data on the amounts and retention of soil N derived from cyanobacterially fixed N2. We will first use photographic data collection to conduct a systematic survey of biofilm incidence and soil coverage in relation to soil properties and management history. For seasonal growth studies, we will identify appropriately sized areas in cropping systems with different histories for sampling of uppermost soils for microscopic examination and measurement of chlorophyll content. For assessment of naturally occurring biofilms of unknown composition (which may contain algae, bacteria and moss), "absolute" quantitation methods will not be possible. Therefore, we plan to track all chlorophyll types over time to discern temporal patterns. Net N2O fluxes will be measured at the time of sampling using a photoacoustic infrared gas monitor (Innova Air Tech Instruments, Ballerup, Denmark) (Adviento-Borbe et al., 2010). These areas will also be sampled for natural abundance isotope composition and total N content (Russow et al., 2005; Woodland and Cook, 2014). Weather data will be obtained from the Agronomy Farm's on-site meteorological station. These data will be analyzed by time-series analyses over sampling dates with chemical and microbiological data as response variables. Experimental plots will be established in a randomized complete block design with subplots designated for either one-time or multiple cyanobacterial applications. Cyanobacteria will be added at different application rates with varying levels of fertilizers and/or liquid manures. Analysis of soils in experimental plots will follow procedures similar to those described for naturally occurring biofilms. Experimental data will be analyzed by ANOVA methods. Finally, petri dish microcosms supporting cyanobacterial biofilms of different ages will be exposed to 15N2 gas in laboratory desiccators for one-week periods. In the beginning of the study, we have the option of calibrating an acetylene reduction assay (ARA) with 15N2 fixation (Holst et al. 2009). Although the latter method is a more reliable approach than ARA (Belnap and Lange, 2001), additional, less expensive analyses may be run if warranted.

Progress 11/19/14 to 06/30/19

Outputs
Target Audience:The target audiences are (1) academic, (2) producer organization and (3) state and federal policty makers. Academic audiences are reached through participation in scientific conferences, review panels and scientific publications. Producer audiences are reached through field days associated to externally funded projects, focus groupmeetings and project advisory boards that include producers and that are our liaison with a larger network of producers. Among the commodity groups are organic producers, the soybean board, and others. And among the policy oriented groups are the Chesapeake Bay Commission and the Pennsylvania Department of Agriculture. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?Students continue improving applications of machine learning techniques. In fact, machine learning let us discern how soil respiration drove nitrous oxide emissions. Students and postdocs have learned state-of-the-art techniques to determine the DNA profile of soil microbial communities, to work with stable isotopes as tracers or as indicators of specific metabolic pathways. Postdocs and students are becoming proficient users of the model Cycles and other models. How have the results been disseminated to communities of interest?In the last year, dissemination of results occurred mostly through scientific meetings and publications. What do you plan to do during the next reporting period to accomplish the goals? Nothing Reported

Impacts
What was accomplished under these goals? Cover crops: We developed and validated a method to estimate nitrogen in the biomass of different cover crops. We showed that relatively low cost hand held devices are as good or better than expensive methods using hyperspectral sensors. We also provided quantitative measures and context to inteprete the potential of covercrops to enhance or mitigate global warming. This was a reponse to a high profile manuscript highlighting the potential of cover crops to increase warming that we deemed exaggerated, but interesting to account for interactions between snow and plant cover. We also quantified nitrous oxide emission in systems with large inputs of nitrogen in organic form, and revealed that hypoxia produced by high respiration is the main explanation for high emission. Modeling: The simulation model Cycles has been made available as an online tool accessible to the general public. The interface continues to be refined. A tool for large scale simulations has been made available through the Institute of Scientific Information (ISI) of the University of Southern California. Although the system is now only available for developers, users can run crops in the cropland area of South Sudan and Ethiopia, contrasting the impact of planting date, nitrogen fertilization rate and weed pressure. Bioenergy crops: The analysis of 5N isotopes in a long term experiment has been completed and shows substantial recycling of nitrogen in this perennial crop. The nitrogen recovering efficiency, meaning the amount of fertilizer that remains in the soil-plant system is extremely high. Willow systems have very little leakage of nitrogen. We also found that in grass crops, emission of nitrous oxide can be relatively low in systems without mineral nitrogen excess, even though conditions for emissions appear to be favorable. Nitrogen fixation in soil biofilms: Screening of 100 enrichment cultures from local soil surfacedthree strains of cyanobacteria that exhibited robust growth on nitrogen-free solid media and consistent microscopic appearance as filamentous, heterocystous cyanobacteria. One enrichment grew reliably in liquid nitrogen-free media and was selected for comparison with pure cultures of commercial strains of other heterocystous cyanobacteria. Growth and biomass density of DG1 and commercial strains on moist, N-limited soils were tracked using chlorophyll a measurements and water flush tests. Anabaena spp. grew faster on soil surfaces, but their 80-day SSCs did not adhere to soil as well as DG1 or Nostoc spp. in water flush tests. The ability of DG1 and Nostoc spp. to produce flocculated growth in liquid culture appeared to be associated with greater soil adherence. While Nostoc spp. formed stable SSCs in soil microcosms, they exhibited lower growth rates and biomass densities than DG1. Attempts to purify the cyanobacterial strain(s) from other bacteria in the DG1 enrichment were unsuccessful. The artificial soil surface consortia formed by DG1 showed good potential for use as a renewable nitrogen source for agroecosystems.

Publications

Type: Journal Articles Status: Published Year Published: 2019 Citation: Rau, B. M., Dell, C. J., Saha, D., Kemanian, A. R., & Adler, P. R. (2019). Herbaceous perennial biomass production on frequently saturated marginal soils: Influence on N2O emissions and shallow groundwater. Biomass & Bioenergy, 122, 90-98.
Type: Journal Articles Status: Published Year Published: 2019 Citation: Pravia, M. V., Kemanian, A. R., Terra, J. A., Shi, Y., Macedo, I., & Goslee, S. (2019). Soil carbon saturation, productivity, and carbon and nitrogen cycling in crop-pasture rotations. Agricultural Systems, 171, 13-22.
Type: Journal Articles Status: Published Year Published: 2019 Citation: Stefani Fae, G., Montes, F., Bazilevskaya, E., & Kemanian, A. R. (2019). Making soil particle size analysis by laser diffraction compatible with standard soil texture determination methods. Soil Science Society of America Journal, 83(4), 1244-1252.
Type: Journal Articles Status: Published Year Published: 2019 Citation: White, C.W., B. Bradley, D.M. Finney, and J.P. Kaye. 2019. Predicting cover crop nitrogen content with a handheld normalized difference vegetation index meter. Agricultural and Environmental Letters 4:190031. doi:10.2134/ael2019.08.0031
Type: Journal Articles Status: Published Year Published: 2019 Citation: Zhi, W., L. Li, W. Dong, W. Brown, J. Kaye, C. Steefel, and K.H. Williams. 2019. Distinct source water chemistry shapes contrasting concentration-discharge patterns. Water Resources Research, 55:42334251. https://doi.org/10.1029/2018WR024257
Type: Journal Articles Status: Published Year Published: 2019 Citation: Hunter, M.C., Schipanski, M.E., Burgess, M.H., LaChance, J.C., Bradley, B.A., Barbercheck, M.E., Kaye, J.P., and D.A. Mortensen. 2019. Cover crop mixture effects on maize, soybean, and wheat yield in rotation. Agricultural and Environmental Letters 4:180051. doi:10.2134/ael2018.10.0051
Type: Journal Articles Status: Published Year Published: 2019 Citation: Murrell E.G., Ray S., Lemmon M.E., Luthe D.S., Kaye J.P. 2019. Cover crop species affect mycorrhizae-mediated nutrient uptake and pest resistance in maize. Renewable Agriculture and Food Systems. https://doi.org/10.1017/S1742170519000061
Type: Journal Articles Status: Published Year Published: 2019 Citation: Hoagland, B., C. Schmidt, T. Russo, R. Adams, J. Kaye. 2019. Controls on nitrogen transformation rates on restored floodplains along the Cosumnes River, California. Science of the Total Environment 649: 979994
Type: Journal Articles Status: Published Year Published: 2019 Citation: Kizewski, F.R., J.P. Kaye, and C.E. Mart�nez. 2019. Nitrate transformation and immobilization in particulate organic matter incubations: Influence of redox, iron and (a)biotic conditions. PLoS ONE 14 (7): e0218752. https://doi.org/10.1371/journal. pone.0218752
Type: Other Status: Published Year Published: 2019 Citation: Hunter, M., C.M. White, J.P. Kaye, and A.R. Kemanian. 2019. Ground-truthing a recent report of cover-crop-induced winter warming. Agricultural and Environmental Letters. doi: 10.2134/ael2019.03.0007
Type: Journal Articles Status: Published Year Published: 2019 Citation: Kaye, J.P, D. Finney, C. White, B. Bradley, M. Schipanski, M. Alonso-Ayuso, M. Hunter, M. Burgess, and C. Mejia. 2019. Managing nitrogen through cover crop species selection in the U.S. mid-Atlantic. Plos One 14(4): e0215448. https://doi.org/10.1371/journal.pone.0215448
Type: Journal Articles Status: Published Year Published: 2019 Citation: Sullivan, P. L., Y. Godd�ris, Y. Shi, X. Gu, J. Schott, E.A. Hasenmueller, J.P. Kaye, C. Duffy, H. Lin, and S. Brantley. 2019. Exploring the effect of aspect to inform future earthcasts of climate-driven changes in weathering of shale. Journal of Geophysical Research: Earth Surface, 124. https:// doi.org/10.1029/2017JF004556
Type: Journal Articles Status: Published Year Published: 2018 Citation: Li, L., R.A. DiBiase, J. Del Vecchio, V. Marcon, B. Hoagland, D. Xiao, C. Wayman, Q. Tang, Y. He, P. Silverhart, I. Szink, B. Forsythe, J.Z. Williams, D. Shapich, G.J. Mount, J. Kaye, L. Guo, H. Lin, D. Eissenstat, A. Dere, K. Brubaker, M. Kaye, K.J. Davis, T. Russo, and S.L. Brantley. 2018. The effect of lithology and agriculture at the Susquehanna Shale Hills Critical Zone Observatory. Vadose Zone J. 17:180063. doi:10.2136/vzj2018.03.0063
Type: Journal Articles Status: Published Year Published: 2019 Citation: Brantley, S.L., T. White, N. West, J.Z. Williams, B. Forsythe, D. Shapich, J. Kaye, H. Lin, Y. Shi, M. Kaye, E. Herndon, K.J. Davis, Y. He, D. Eissenstat, J. Weitzman, R. DiBiase, L. Li, W. Reed, K. Brubaker, and X. Gu. 2018. Susquehanna Shale Hills Critical Zone Observatory: Shale Hills in the context of Shavers Creek watershed. Vadose Zone J. 17:180092. doi:10.2136/vzj2018.04.0092
Type: Journal Articles Status: Published Year Published: 2018 Citation: Baraibar B., D. Mortensen, M. Hunter, M. Barbercheck, J. Kaye, D Finney, W. Curran, J. Bunchek, and C. White (2018) Growing degree days and cover crop type explain weed biomass in winter cover crops. Agronomy for Sustainable Development 38:65 https://doi.org/10.1007/s13593-018-0543-1
Type: Journal Articles Status: Published Year Published: 2018 Citation: Weitzman, J. N., and J.P. Kaye. 2018. Nitrogen budget and topographic controls on nitrous oxide in a shale-based watershed. Journal of Geophysical Research: Biogeosciences, 123. https://doi.org/10.1029/2017JG004344
Type: Journal Articles Status: Published Year Published: 2019 Citation: Cyanobacterial soil surface consortia mediate N cycle processes in agroecosystems. Peng, X. & Bruns, M. V., Jan 4 2019, In: Frontiers in Environmental Science. 6, JAN, 156.
Type: Journal Articles Status: Published Year Published: 2019 Citation: Development of a nitrogen-fixing cyanobacterial consortium for surface stabilization of agricultural soils. Peng, X. & Bruns, M. V., Apr 15 2019, In: Journal of Applied Phycology. 31, 2, p. 1047-1056 10 p.
Type: Journal Articles Status: Published Year Published: 2019 Citation: Duckweed as an agricultural amendment: Nitrogen mineralization, leaching, and sorghum uptake. Kreider, A. N., Fernandez Pulido, C. R., Bruns, M. V. & Brennan, R. A., Mar 1 2019, In: Journal of Environmental Quality. 48, 2, p. 469-475 7 p.

Progress 10/01/17 to 09/30/18

Outputs
Target Audience:Our target audiences are scientists, growers, NGOs, and policy makers with state and federal agencies. We consider our stakeholders to be anyone interested in novel, sustainable ways to manage flows of C and N in agricultural and biofuel systems. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?Several students were trained in cutting edge methods of molecular soil microbiology. Two graduate students were trained in simulation modeling, specifically with the Cycles and PIHM models.One graduate student was trained in root biology and a second learned to conduct rainfall simulations over cover cropping systems. Postdocs were trained in the area of greenhouse gas measurement and were mentored in the areas of peer review publication, job talks, and interview tactics. Postocs and young scientists were given the opportunity for science outreach through a SSSA podcast. How have the results been disseminated to communities of interest?We held field days on two commercial farms and conducted a half day workshopat a grower conference (Pennsylvania Association of Sustainable Agriculture) s to reach farmers. We participated in a two-day meeting with the Lake Sunapee Protective Association, discussing the usage of data on lake water quality emerging from modeling current and historic land use change. To reach scientists, we published in the peer reviewed literature, and we presented our work at regional and national conferences. To reach policy makers and other stakeholders,our work was highlighted ina podcast sponsored by the Soil Science Society of America. What do you plan to do during the next reporting period to accomplish the goals?We will continue to maintain our long-term cover crop experiment and to synthesize work from that site, as well as continue our experiments on silage and energy crops. We will engage farmers and NGOs at an annual advisory board meeting for the site. One student recently conducted simulated extreme rain events on four different cover crops and that work will result in an MS thesis and publication. We have several experiments underway that test the prospect of interseeding cover crops beneath growing corn. In the coming year we will synthesize and publish that work and disseminate results to farmers.

Impacts
What was accomplished under these goals? We have maintained a long-term cover crop experiment that contrasts six monocultures and four mixtures. This experiment enables us to help farmers with cover crop species selection and to assess whether mixtures are superior to monocultures in providing different ecosystem services.This year we published a major synthesis paper from the project (Finney et al. 2017). In this three-year study of eight ecosystemservices, certain services typicallyco-occurred, or were bundled. One service 'bundle' included cover crop biomass production, weed suppression, and nitrogen retention, whileanother set of bundled services included cash crop production, nitrogen supply, and profitability. Importantly, we found strong tradeoffs among these bundles because as some services increased other disservices arose, limiting multifunctionality. Functionally diverse mixtures did not increase ecosystems services over the best monoculture, but they did ameliorated disservices associated with certain monocultures, thereby increasing cover cropmultifunctionality. In a subset of plots from this experiment we conducted studies of cover crop roots and their impact on soil C stablization. The roots of triticale, crimson clover, and canola were compared in monoculture and mixtures. Triticale produced more total root biomass than the other treatments, in part because it produced more between-row (our cover crops were planted in 7 inch rows) root biomass. A mixture of clover, canola and triticalehad more root biomass between and within rows than the crimson clover monoculture in spring. Therefore, combining clover with grass and certain brassica species may increase total root biomass production and root distribution, while also decreasing root C:N compared to grass species. Using a novel isotope labeling technique, we tracedcover crop rhizodeposition C into soil pools in a greenhouse study. Crimson clover potshad more rhizodeposition C in the light soil fraction per gram of root C and per meter root length than canola or triticale. However, crimson clover also contained less root biomass and root length than other species so alarger quantity of canola and triticale rhizodeposition C was stabilized in silt and clay fractions compared to crimson clover. A key outcome from this study is that cover crops immediately contribute C to stable soil pools (mineral associated) regardless of species. We completed the third year of an experiment to measure productivity and adaptation to biotic and abiotic stresses of mixtures of corn, sorghum, sunflower and soybean for silage. We started a project to measure nitrogen leaching and nitrogen recovery in willow crops, as well as a new project to use willow at Penn State's living filter. We continue monitoring carbon and water fluxes using edddy covariance towers installed in a 35 ac willow stand, completing almost 5 years of data collection. The cultivars being monitored include new hybrids being deployed in New York for power generation. We continue applying the models Cycles and PIHM to integrated assessment of modeling practices in agricultural and non-agricultural lake watersheds (Mendota Lake, WI; Oneida Lake, NY; Sunapee Lake, NH), in the Midwest where we are assessing the environmental benefits of biomass production for bioenergy, and in the Chesapeake Bay where we are assessing intercropping cover crops at multiple locations. Observations of recurrent, photosynthetic cyanobacterial films on the surfaces of many agricultural soils at the Penn State Agronomy Farm, led to investigations of these surface consortia (SSCs) as renewable sources of biologically fixed N. We used serial transfers in N-free culture media to enrich for an N2-fixing microbial consortium (DG1) from surface soil samples. Attempts to purify the cyanobacteria from other bacteria in the DG1 enrichment were unsuccessful. Based on metagenomics analysis, the DG1 consortium contained one or more closely related Cylindrospermum spp., which are heterocystous cyanobacteria in the Nostocacae family, and six other bacterial genotypes including Ensifer adherens. The presence of bacterial associates did not interfere with rapid growth and high biomass density in soil microcosms, as well as biofilm stability in water-flush tests. The growth of DG1 in N-free medium compared favorably with pure cultures of commercial strains of heterocystous cyanobacteria as tracked using increases in chlorophyll a and resistance to water-flush tests. While commercially available Nostoc spp. formed stable SSCs in soil microcosms, they exhibited lower growth rates and biomass densities than DG1. Stable isotope 15N2 gas uptake experiments by DG1 suspensions gave estimates of 5-10 kg N per hectare annually. Additional experiments were conducted with soil microcosms and simulated rainfall. DG1 performed well across a range of soil mineral N concentrations and retained a significant amount of soil nitrate. Effects of soil nitrate concentration, cyanobacterial application rate and establishment time were tested. Cyanobacterial growth was affected by cyanobacterial application rate; biomass recovery was affected by establishment time; and N retention was affected by all three independent variables. After integrating all results in our studies, we concluded that lower application rates (ca. 0.9 g dry biomass m-2) and a period of establishment time (ca. 7 days without significant rain) will be efficient and cost-effective in future agricultural applications.

Publications

Type: Conference Papers and Presentations Status: Published Year Published: 2018 Citation: Mejia, C, Kaye, J. 2018. Testing the erosion protection potential of three different cover crops. 8th Annual PSU Sustainable Cropping Systems Symposium.
Type: Conference Papers and Presentations Status: Published Year Published: 2017 Citation: Amsili, J. and J.P. Kaye. 2017. Root traits of cover crop monocultures and mixtures. Soil Science Society of America Annual Meeting, Tampa Florida.
Type: Conference Papers and Presentations Status: Published Year Published: 2017 Citation: Amsili, J. and J.P. Kaye. 2017. Root traits of cover crop monocultures and mixtures. Northeast Cover Crop Council Meeting, Ithaca, NY.
Type: Conference Papers and Presentations Status: Published Year Published: 2018 Citation: Finney, DM. 2018. Ecosystem services from cover crop mixtures and monocultures in an organic feed and forage rotation. Organic Farming Research Foundation Conference. New Brunswick, NJ.
Type: Journal Articles Status: Published Year Published: 2017 Citation: Finney, D., E. Murrell, C. White, B. Baraibar, M. Barbercheck, B. Bradley, S. Cornelisse, M. Hunter, J. Kaye, D. Mortensen, C. Mullen, and M. Schipanski. 2017. Ecosystem services and disservices are bundled in simple and diverse cover cropping systems. Agricultural and Environmental Letters. doi: 10.2134/ael2017.09.0033
Type: Journal Articles Status: Under Review Year Published: 2018 Citation: Cloutier M, Murrell EG, Barbercheck ME, Kaye JP, Finney DM, Gonz�lez IG, Bruns MA. In review. Cover crop type and soil texture shape fungal assemblages and functions in a multi-species cover crop experiment. Applied Soil Ecology.
Type: Journal Articles Status: Under Review Year Published: 2018 Citation: Morris A., S. Isbell, D. Saja, and J. Kaye. In review. Mitigating nitrogen pollution with under-sown legume-grass cover crop mixtures in winter cereals Agricultural Systems
Type: Theses/Dissertations Status: Published Year Published: 2018 Citation: Amsili, Joseph. 2018. Root traits of cover crops and their influence on soil organic carbon stabilization. Master of Soil Science Thesis. Penn State
Type: Journal Articles Status: Published Year Published: 2017 Citation: Rosenzweig, S.T., M.E. Schipanski, and J.P. Kaye. 2017. Rhizosphere priming and plant-mediated cover crop decomposition. Plant and Soil 417: 127-139. https://doi.org/10.1007/s11104-017-3246-5.
Type: Journal Articles Status: Published Year Published: 2017 Citation: Finney, D.M., J.S. Buyer, and J.P. Kaye. 2017. Living cover crops have immediate impacts on soil microbial community structure and function. Journal of Soil and Water Conservation. July/August 2017 vol. 72 no. 4 361-373. doi: 10.2489/jswc.72.4.361
Type: Journal Articles Status: Published Year Published: 2018 Citation: Peng, X, MA Bruns. 2018. Development of a nitrogen-fixing cyanobacterial consortium for surface stabilization of agricultural soils. J Applied Phycology, published online 20 August, https://doi.org/10.1007/s10811-018-1597-9
Type: Journal Articles Status: Published Year Published: 2018 Citation: Chen, L, ML Hile, EE Fabian-Wheeler, Z Xu, MA Bruns, V Brown. 2018. Iron oxide to mitigate hydrogen sulfide gas release from gypsum-bedded dairy manure storages. Transactions of the American Society of Agricultural and Biological Engineers 61:1101-1112.
Type: Conference Papers and Presentations Status: Published Year Published: 2018 Citation: Bruns MA. 2018. How might soil properties constrain phytobiome modification? Oral presentation at Wild and Tamed Phytobiomes, 21st Annual Penn State Plant Biology Symposium, University Park, PA, June 19-22, 2018.
Type: Conference Papers and Presentations Status: Published Year Published: 2018 Citation: Bruns MA, X Peng, R Trexler, and T Bell. 2018. Provision of agroecosystem services by soil-surface microbial consortia. Poster presentation at Wild and Tamed Phytobiomes, 21st Annual Penn State Plant Biology Symposium, University Park, PA, June 19-22, 2018.
Type: Conference Papers and Presentations Status: Published Year Published: 2017 Citation: Bruns MA. 2017. Importance of understanding and shaping microbial responses to climate-adaptive management. Plenary for USDA-NIFA AFRI Project Directors Meeting, Washington, DC, October 21, 2017.
Type: Conference Papers and Presentations Status: Published Year Published: 2017 Citation: Bruns MA. 2017. Integrated management, underexplored microbial metabolisms, and nutrient flow in soils. Oral presentation 256-4 at the International Annual Meeting of the Soil Science Society of America, Tampa, FL, Oct. 22-25, 2017
Type: Conference Papers and Presentations Status: Published Year Published: 2017 Citation: Ball E, Bruns MA, Karsten H, Dell C. 2017. Soil redox potential and carbon fractions in manured and cover-cropped soils under reduced tillage. Poster no. 313-1233 at the 2017 International Annual Meeting of the Soil Science Society of America, Tampa, FL, Oct. 22-25, 2017
Type: Conference Papers and Presentations Status: Published Year Published: 2017 Citation: Bhowmik A, MA Bruns, and T Bell. 2017. Assessing the abundance and diversity of nrfA genes, molecular markers for nitrite ammonification, in manures. Oral presentation 406-4 at the International Annual Meeting of the Soil Science Society of America, Tampa, FL, Oct. 22-25, 2017
Type: Journal Articles Status: Published Year Published: 2017 Citation: Cloutier ML, E Murrell, M Barbercheck, I Garcia, J Kaye, MA Bruns. 2017. What actually controls fungal community structure in agroecosystems? An analysis of cover crop treatments and soil physiochemical parameters. Poster presentation at 8th Argonne Soil Metagenomics Meeting, Nov. 1-3, 2017, Argonne, IL.
Type: Journal Articles Status: Published Year Published: 2017 Citation: Cloutier ML, E Murrell, M Barbercheck, I Garcia, J Kaye, MA Bruns. 2017. Fungal communities associated with cover cropping in a tilled agroecosystem. Poster presentation at Northeast Cover Crop Council Educational Meeting, Cornell University, Nov. 8, 2017.
Type: Conference Papers and Presentations Status: Published Year Published: 2017 Citation: Saha D, A Bhowmik, AR Kemanian, JP Kaye, MAV Bruns. 2017. Assessing in-situ sources of soil N2O emissions in response to manure and residue management in organic systems. Poster 1106 at the 2017 International Annual Meeting of the Soil Science Society of America, Tampa, FL, Oct. 22-25, 2017
Type: Journal Articles Status: Published Year Published: 2018 Citation: Woodbury, PB, Kemanian AR, Jacobson, M, and Langholtz, M. 2018. Improving water quality in the Chesapeake Bay using payments for ecosystem services for perennial biomass for bioenergy and biofuel production. Biomass and Bioenergy 114:132-142
Type: Journal Articles Status: Published Year Published: 2018 Citation: Cobourn, K. M., Carey, C. C., Boyle, K. J., Duffy, C. J., Dugan, H. A., Farrell, K. J., Fitchett, L., Hanson, P. C., Hart, J. A., Henson, V. R., Kemanian, A. R., & others (2018). From concept to practice to policy: modeling coupled natural and human systems in lake catchments. Ecosphere, 9(5), e02209.
Type: Journal Articles Status: Published Year Published: 2018 Citation: Hoffman, A. L., Kemanian, A. R., & Forest, C. E. (2018). Analysis of climate signals in the crop yield record of sub-Saharan Africa. Global Change Biology, 24(1), 143-157.
Type: Journal Articles Status: Published Year Published: 2018 Citation: Saha, D., Kemanian, A. R., Montes, F., Gall, H. E., Adler, P. R., & Rau, B. M. (2018). Lorenz curve and Gini coefficient reveal hot spots and hot moments for nitrous oxide emissions. Journal of Geophysical Research: Biogeosciences, 123(1), 193-206.
Type: Journal Articles Status: Published Year Published: 2018 Citation: Wolfe, D. W., DeGaetano, A. T., Peck, G. M., Carey, M., Ziska, L. H., Lea-Cox, J., Kemanian, A. R., Hoffmann, M. P., & Hollinger, D. Y. (2018). Unique challenges and opportunities for northeastern US crop production in a changing climate. Climatic Change, 146(1-2), 231-245.
Type: Journal Articles Status: Published Year Published: 2018 Citation: Fabio, E. S., Kemanian, A. R., Montes, F., Miller, R. O., & Smart, L. B. (2017). A mixed model approach for evaluating yield improvements in interspecific hybrids of shrub willow, a dedicated bioenergy crop. Industrial Crops and Products, 96, 57-70.

Progress 10/01/16 to 09/30/17

Outputs
Target Audience:The target audiences are (1) academic, (2) producer organization and (3) state and federal policty makers. Academic audiences are reached through participation in scientific conferences, review panels and scientific publications. Producer audiences are reached through field days associated to externally funded projects, focus groups meetings and projects advisory boards that include producers and that are our liaison with a larger network of producers. Among the commodity groups are organic producers, the soybean board, and others. And among the policy oriented groups are the Chesapeake Bay Commission and the Pennsylvania Department of Agriculture. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?Students and postdocs have learned state-of-the-art techniques to determine the DNA profile of soil microbial communities, to work with stable isotopes as tracers or as indicators of specific metabolic pathways. They have also polished the use of novel statistical techniques (non-parametric methods) that are enabling a more efficient use of research data, and accelerating data analysis in general. A smaller, focused group of postdocs and reseach associates are gaining expertise in the use of simulation models, particularly the models Cycles and PIHM. How have the results been disseminated to communities of interest?Our groups have hosted two field days (Cover Crops Cocktail Project and Reduce Tillage Organic Experiment), two meetings the corresponding advisory boards, two tours of our bioenergy fields with willow (one of the high school teachers), and substantial academic exchange through participation in research meetings. Our combined publication output is higher than five peer review publication per PI per year. What do you plan to do during the next reporting period to accomplish the goals?Experiments are undergoing to partition nitrous oxide production into nitrification and denitrification. This is being accomplished by using a noverl technique that relies on isotopomers - i.e. molecules that have the same composition but have a different abundance of the 15N stable isotope at different positions in the molecule (in nitrous oxide, the nitrogen atoms are called alfa or beta depending on their position with respect to oxygen.). The characterization of the nitrogen cycle in different cover crop polyclutures remains an are of interest. A new area of research involved studying polycultures to produce silage based on corn but adding sunflower, sorghum and soybean to the mix. In addition, our research is expanding to a characterization of the phosphorous cycle and the control of erosion through cover cropping. A novel analysis of crop yields in response to climate will provide new insights into the strengths and vulnerabilities of the US agriculture when facing increased climate variability, including extreme events. Model development continues, and our focus is to produce detailed maps of the changing outline of flooding due both land use change and more frequent extreme precipitation events. Plot level erosion research will provide a plot view of the changes to come in agriculture, and watershed scale modeling will allow projecting these changes to much larger physical and social domains.

Impacts
What was accomplished under these goals? Technology remains the main driver of grain crop yield increase in Sub-Saharan Africa. Because this regions instability spills over to Europe through migration that causes political and social unrest in Europe, developing stable agricultural systems remains in those regions remains a priority. Our novel analysis of crop yield in Sub Saharan Africa revealed that despite a negative effect of a changing climate, improved technology drives the increases in yield. In fact, there is substantial room to improve the agricultural output of Sub Saharan African countries, but some regions, particularly the Sahel, might be threatened by further marginalization of agriculture due to a changing climate. On the United States agricultural systems, our research established that cover cropping, which means having a growing crop while the main cash crop is not on the ground, is a practice that produces substantial benefits in the form of ecosystem services. Cover cropping enables high output agricultural production by minimizing potential negative effects such as nitrogen leaching, and by bringing novel benefits for biodiversity and soil health preservation. Polycultures of cover crops provide flexibility for the delivery of multiple ecosystem services. Regarding bioenergy crops, we have shown that an expansion of switchgrass on croplands dominated by corn can produce the same amount of biofuel derived from corn ethanol, with a substantial reduction in nitrogen leaching to surface waters. Among the surprising outcomes of this research is that fertilized switchgrass produces more economic and ecological benefits than unfertilized switchgrass or than simply setting aside lands. Both the discovery of novel microbial processes related to the nitrogen cycle and the quantification of the nitrogen fluxes through these processes, are providing a more complex picture of the nitrogen cycle than previously thought. In fact, much of the inability to fully explain nitrogen fluxes in ag systems that affect productivity and pollution may stem for our poor understanding of the microbiome complexity. This improved understanding may offer chances to develop new technologies to deliver nitrogen to plants, to prevent pollution, or to treat manure before or when applied to agricultural lands.

Publications

Type: Journal Articles Status: Published Year Published: 2017 Citation: Bhowmik A, Cloutier M, Ball E, Bruns MA. 2017. Underexplored microbial metabolisms for enhanced nutrient cycling in agricultural soils. AIMS Microbiology 3(4): 826-845. DOI: 10.3934/microbiol.2017.4.826.
Type: Journal Articles Status: Published Year Published: 2017 Citation: Rojas, CR, Vargas, I, Bruns, MA, Regan J. 2017. Electrochemically active microorganisms from an acid mine drainage-affected site promote cathode oxidation in microbial fuel cells. Bioelectrochemistry, 118C:139-146.
Type: Journal Articles Status: Published Year Published: 2016 Citation: Moon, JB, DH Wardrop, MA Bruns, RM Miller, KJ Naithani. 2016. Land-use and land-cover effects on soil microbial community abundance and composition in headwater riparian wetlands. Soil Biol. Biochem. 97:215-233.
Type: Journal Articles Status: Published Year Published: 2017 Citation: Murrell, E.M., Lemmon, M.E., Ray, S. and Kaye, J.P., 2017, March. Legacy effects of preceding cover crop species on mycorrhizae, nutrients, and plant-insect interactions in a cash crop. In INTEGRATIVE AND COMPARATIVE BIOLOGY (Vol. 57, pp. E118-E118). JOURNALS DEPT, 2001 EVANS RD, CARY, NC 27513 USA: OXFORD UNIV PRESS INC.
Type: Journal Articles Status: Published Year Published: 2017 Citation: Kaye, J. P., & Quemada, M. (2017). Using cover crops to mitigate and adapt to climate change. A review. Agronomy for Sustainable Development, 37(1), 4.
Type: Journal Articles Status: Published Year Published: 2017 Citation: White, C.M., DuPont, S.T., Hautau, M., Hartman, D., Finney, D.M., Bradley, B., LaChance, J.C. and Kaye, J.P., 2017. Managing the trade off between nitrogen supply and retention with cover crop mixtures. Agriculture, Ecosystems & Environment, 237, pp.121-133.
Type: Journal Articles Status: Published Year Published: 2017 Citation: Saha, D., Kemanian, A.R., Rau, B.M., Adler, P.R. and Montes, F., 2017. Designing efficient nitrous oxide sampling strategies in agroecosystems using simulation models. Atmospheric Environment, 155, pp.189-198.
Type: Journal Articles Status: Published Year Published: 2017 Citation: Woodbury, P.B., Kemanian, A.R., Jacobson, M. and Langholtz, M., 2017. Improving water quality in the Chesapeake Bay using payments for ecosystem services for perennial biomass for bioenergy and biofuel production. Biomass and Bioenergy.
Type: Journal Articles Status: Published Year Published: 2017 Citation: Hoffman, A.L., Kemanian, A.R. and Forest, C.E., 2017. Analysis of climate signals in the crop yield record of sub?Saharan Africa. Global Change Biology.

Progress 10/01/15 to 09/30/16

Outputs
Target Audience:Academic Colleagues Government agencies and non-government organizations related to environment Government agencies and non-government organizations related to agricultural production Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? Nothing Reported How have the results been disseminated to communities of interest?NEWBio Annual meeting (July 31, University Park PA): This meeting collects researchers for the NE United States and disseminates the results of our research to our stakeholders represented by an advisory board of environmental and industry groups, and targeted invited participants (e.g. Antares Inc.) Cover crops research is disseminated to a broad audience of producers to several field days and participation in the PASA meetings, among other venues. What do you plan to do during the next reporting period to accomplish the goals?1) Cover experiments continues, with a further expansion of activities to on farm research. 2) Model development continues, as Cycles is being expanded to account for phosphorus cycling. 3) A 15N study focused on N cycling in the perennial shrub willow is near completion; this year we will complete the first root sampling of 15N labeled perennial plants in the United States. 4) The plausibility of using innoculum of cyanobacteria for field management is being tested in field experiments at the Rock Springs experimental farm.

Impacts
What was accomplished under these goals? 1) A 3-yr study with monocultures and mixtures of six cover crop species (cereal rye [Secale cereale L.], oat [Avena sativa L.], common medium red clover [Trifolium pratense L.], Austrian winter pea [Pisum sativum L.], forage radish [Raphanus sativus L.], and winter canola [Brassica napus L.]) were planted in a wheat (Triticum aestivum L.)-maize (Zea mays L.)-soybean [Glycine max (L.) Merr.] rotation after wheat and after maize. Our study demonstrated that (i) cover crop mixtures retain higher diversity when allowed sufficient growth in fall; (ii) cereal rye dominates mixtures in spring, particularly when fall planting is delayed; (iii) grasses overperform in mixtures compared to their growth in monocultures; (iv) brassicas underperform in mixtures vs. monocultures; and (v) legume growth in mixtures depends on species and planting time. 2) We developed a model-data fusion approach to calibrate a model of cover crop (CC) residue N mineralization and pre-emptive competition for soil NO3-. The model, calibrated with a data set of 199 observations from four CC experiments in central Pennsylvania, explained 82% of the variation in corn yield response. Parameters representing the C humification coefficients for decomposed residues from winterkilled (εwk = 0.00) and winter-hardy (εwh = 0.40) CCs suggest that all winterkilled CCs resulted in net N mineralization, probably due to the longer period of time for decomposition of winterkilled residues. However, the yield response per unit of potentially mineralized N was greater for winter-hardy CCs (αwh = 0.034 with tillage, αwh = 0.020 with no-till) than for winterkilled CCs (αwk = 0.0084), probably due to the improved synchrony between corn N demand and the decomposition of winter-hardy CC residues relative to winterkilled residues. Pre-emptive competition for soil NO3- led to a reduction in the corn yield response. Because the model is based on ecological processes and can be calibrated with data sets from simple field experiments, the model-data fusion approach could be widely used to guide adaptive management of CCs and N fertilizer applications in a subsequent corn crop. 3) We showed that cover crops grown in rotation with cash crops are a realistic strategy to increase agroecosystem diversity. We evaluated the prediction that further increasing diversity with cover crop polycultures would enhance ecosystem services and multifunctionality in a 2-year study of eighteen cover crop treatments ranging in diversity from one to eight species. Five ecosystem services were measured in each cover crop system and regression analysis used to explore the relationship between multifunctionality and several diversity indices. Indices of functional diversity, particularly the distribution of trait abundances, were stronger predictors of multifunctionality (marginal R2=0·15-0·38) than other simpler predictors. In a corn production system, simply increasing cover crop species richness will have a small impact on agroecosystem services, but designing polycultures that maximize functional diversity may lead to agroecosystems with greater multifunctionality. 4) Future liquid fuel demand from renewable sources may, in part, be met by converting the seasonally wet portions of the landscape currently managed for soil and water conservation to perennial energy crops. However, this shift may increase nitrous oxide (N2O) emissions, thus limiting the carbon (C) benefits of energy crops. We measured N2O emissions and associated environmental drivers during the transition of perennial grassland in a Conservation Reserve Program (CRP) to switchgrass (Panicum virgatum L.) and Miscanthus x giganteus in the bottom 3-ha of a watershed in the Ridge and Valley ecoregion of the northeastern United States. We found that N-fertilized switchgrass and Miscanthus treatments had 3 and 6-times higher cumulative flux respectively than the CRP in the footslope, but at other landscape positions fluxes were similar among land uses. A peak N2O emission event, contributing 26% of the cumulative flux, occurred after a 10.8-cm of rain (hurricane). Prolonged subsoil saturation coinciding with high mineral N concentration fueled N2O emission hot spots in the footslopes under energy crops. Our results suggest that mitigating N2O emissions during the transition of CRP to energy crops would mostly require a site-specific management of the footslopes. 5) Root water uptake is an essential component of crop models since it affects plant growth and, through its effect on the soil water balance, multiple soil and nutrient cycling processes. We compared the water uptake methods implemented in six crop models: APSIM, CropSyst, DSSAT, EPIC, SWAP and WOFOST. The main difference among methods derived from the degree to which each model enabled the use of water in the subsoil (below 0.5m). In a rooted, 1-m deep silt loam soil in which the root density decreased geometrically with depth and which was subjected to an evaporative demand of 5mmd−1 for 60 days, APSIM, EPIC, DSSAT and SWAP transpired about 83% of the total plant available water while SWAP and CropSyst transpired about 65% of it. When methods were compared with initially dry bottom soil layers, cumulative transpiration became similar for all methods, while the opposite initial condition exacerbated differences. All methods, except CropSyst, increased transpiration as the evaporative demand rose to relatively high rates (10mmd−1) because they lack a feedback mechanism that reduces transpiration when the demand exceeds the plant's ability to conduct water. CropSyst, DSSAT, EPIC and SWAP developed a drying front, as usually observed in field conditions, while APSIM and WOFOST showed relatively uniform water depletion with depth in the soil profile. In conclusion, the models differ meaningfully in their simulation of water uptake and careful consideration of these differences is needed to properly use and interpret the outcome of model simulations. These models are widely used to assess food production under management and Climate Change scenarios. 6) No-till is expanding worldwide, particularly in the eastern Pampas of South America. We studied the impact of this particular form of agricultural intensification on the attainable wheat yield (Yatt) and the yield gap (Yg), with the latter defined as the difference between Yatt and actual yield (Ya). Our measure of agricultural intensification is the length in years of continuous cropping (YCC). We computed both Yatt and Yg from 1072 wheat yield records obtained from producers between 2009 and 2012 using a stochastic frontier production function that uses a climatic index (CI), cultivar, region and YCC as explanatory variables, and includes a term representing the inefficiency function. The mean Yatt was 4.9±0.7Mgha−1. Its variation was a function of the cultivar and the interaction of CI and YCC. Our results indicate that under low CI (poor for wheat), intensifying crop production with continuous annual no-till cropping can cause a measurable reduction in Yatt and Ya. The negative effect of YCC on Ya was significantly higher under weather conditions unfavorable for wheat growth. These effects could not be compensated for with the maximum N fertilization rates used by producers under low CI or with a rotation of annual crops. Our interpretation is that shifting cropping systems from a crop-pasture rotation to continuous annual no-till cropping generates a progressive limitation in soil productivity that reduces wheat yield and increases its inter annual variability. To our knowledge, this is the first report of decreasing yield due to continuous no-till annual agriculture.

Publications

Type: Journal Articles Status: Published Year Published: 2016 Citation: Murrell, Ebony G., Meagan E. Schipanski, Denise M. Finney, Mitchell C. Hunter, Mac Burgess, James C. LaChance, Barbara Baraibar, Charles M. White, David A. Mortensen, and Jason P. Kaye. Achieving Diverse Cover Crop Mixtures: Effects of Planting Date and Seeding Rate. Agronomy Journal (2016).
Type: Journal Articles Status: Published Year Published: 2016 Citation: White, Charles M., Denise M. Finney, Armen R. Kemanian, and Jason P. Kaye. A ModelData Fusion Approach for Predicting Cover Crop Nitrogen Supply to Corn. Agronomy Journal (2016).
Type: Journal Articles Status: Published Year Published: 2016 Citation: Finney, Denise M., and Jason P. Kaye. Functional diversity in cover crop polycultures increases multifunctionality of an agricultural system. Journal of Applied Ecology (2016).
Type: Journal Articles Status: Published Year Published: 2016 Citation: Saha, Debasish, Benjamin M. Rau, Jason P. Kaye, Felipe Montes, Paul R. Adler, and Armen R. Kemanian. Landscape control of nitrous oxide emissions during the transition from conservation reserve program to perennial grasses for bioenergy. GCB Bioenergy (2016).
Type: Journal Articles Status: Published Year Published: 2016 Citation: Camargo, G. G. T., and A. R. Kemanian. Six crop models differ in their simulation of water uptake. Agricultural and Forest Meteorology 220 (2016): 116-129.
Type: Journal Articles Status: Published Year Published: 2016 Citation: Ernst, Oswaldo R., Armen R. Kemanian, Sebasti�n R. Mazzilli, M�nica Cadenazzi, and Santiago Dogliotti. Depressed attainable wheat yields under continuous annual no-till agriculture suggest declining soil productivity. Field Crops Research 186 (2016): 107-116.
Type: Books Status: Published Year Published: 2016 Citation: Bruns, Mary Ann. 2016. Bacteria, in Encyclopedia of Soil Science, 3rd ed., (R. Lal, ed.), Taylor and Francis.
Type: Journal Articles Status: Published Year Published: 2016 Citation: Rojas, CR, RM Gutierrez, MA Bruns. 2016. Bacterial and eukaryal diversity in soils forming from acid mine drainage precipitates under reclaimed vegetation and biological crusts. Applied Soil Ecology 105:57-66.

Progress 11/19/14 to 09/30/15

Outputs
Target Audience:Academic Colleagues Government agencies and non-government organizations related to environment Government agencies and non-government organizations related to agricultural production Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? Nothing Reported How have the results been disseminated to communities of interest?The cover crops work has been reported through fields days and a fact sheet available online through the sustainable agriculture link of Penn State: http://extension.psu.edu/plants/sustainable/news/2015/summer-2015/new-fact-sheet-on-cover-crop-mixtures?utm_campaign=Sustainable+Ag+News&utm_medium=email&utm_source=newsletter&utm_content=newsletter_title NEWBio (http://www.newbio.psu.edu/) maintains a profuse list of field and webinars available at the link above. Scientific findings have been disseminated the corresponding journals. What do you plan to do during the next reporting period to accomplish the goals?Experiments on cover crops are on schedule. At least three more publications are under preparation. The simulation model Cycles is evolving into a watershed model that will enable watershed scale simulation of C and N balances.

Impacts
What was accomplished under these goals? 1) Productivity and ecosystem services from multi-species cover crop mixtures were measured in a 2-yr field study of 18 cover crop treatments preceding conventionally tilled corn in central Pennsylvania. Increasing the number of species in a stand increased cover crop biomass (R2 = 0.15). However, mixing cover crop species that were complementary in phenology or N acquisition strategy did not result in mixtures that produced more biomass than high yielding monocultures. Increasing cover crop biomass was positively correlated with several ecosystem services, namely weed suppression, prevention of nitrate leaching, and aboveground biomass N, but negatively impacted inorganic N availability and corn yield in the subsequent cropping season. The cover crop C/N ratio was another determinant of ecosystem services positively related to nitrate leaching prevention, but negatively related to inorganic N availability and corn yield. This study supports the long-held assumption that increasing biomass can enhance certain ecosystem services from cover crops; however, because the mixtures tested did not produce more biomass than high yielding monocultures, opportunities to increase biomass-driven services with mixtures may be limited. The correlation between biomass C/N ratio and ecosystem services in this study also indicates that functional traits, as opposed to biomass alone, will be important for predicting ecosystem services from cover crop mixtures. 2) We used data from a 5-year study of organic cropping systems to investigate soil inorganic N (SIN) variability and nitrate (NO3-) leaching in ENM. Four production systems initiated in 2007 and 2008 in central Pennsylvania varied in crop rotation, timing and intensity of tillage, inclusion of fallow periods, and N inputs. Extractable SIN was measured fortnightly from March through November throughout the experiment, and NO3-N concentration below the rooting zone was sampled with lysimeters during the first year of the 2008 start. The highest SIN concentrations occurred when the average air temperature three weeks prior to measurement was above 21oC. Above this temperature and within 109 days of moldboard plowing, average SIN concentrations were 22.1 mg N kg-1 soil. Other drivers of SIN dynamics were N available from manure and cover crops. Highest average leachate NO3-N concentrations (15.2 ppm) occurred in fall and winter when SIN was above 4.9 mg kg-1 six weeks prior to leachate collection. Late season tillage operations leading to elevated SIN and leachate NO3-N concentrations were a strategy to reduce weeds while meeting consumer demand for organic products. Thus, while tillage that incorporates organic N inputs preceding cash crops can promote synchrony of N mineralization and crop demand, late or post-season tillage promotes NO3- leaching by stimulating SIN pulses that are asynchronous with plant uptake. 3) We investigated how the chemical composition of different residues, (corn and soybean) controls k and h under field conditions in a no-till ecosystem. Using CV-driven shifts in δ13C, we estimated changes in carbon (C) stocks, k and h of both the labile particulate organic matter fraction (CPOM) and the stabilized mineral associated organic matter fraction (CMAOM). After two years of high C inputs (corn: 4.4Mgha−1y−1 aboveground and C:N=78; soybean: 3.5Mgha−1y−1, C:N=17), we found no changes in CPOM and CMAOM stocks in the top 5-cm of soil or in deeper layers. However, CMAOM in corn had higher k (0.06y−1) and C output fluxes (0.67Mgha−1y−1) than in soybean (0.03y−1 and 0.32Mgha−1y−1), but similar rates and fluxes in CPOM in the top 5-cm of soil. In addition, while C inputs to CPOM were also similar for both crops, C inputs from CV to CMAOM were higher in corn (0.51Mgha−1y−1) than in soybean (0.19Mgha−1y−1). Overall, corn plots had higher k and C inputs into CMAOM and therefore higher C cycling in this fraction. Thus, our investigation suggests that the type of crop residue strongly influences C cycling in the topsoil of no-till cropping systems by affecting both the stabilization and the decomposition of soil organic matter.

Publications

Type: Journal Articles Status: Published Year Published: 2015 Citation: Hasenmueller, E. A., Jin, L., Stinchcomb, G. E., Lin, H., Brantley, S. L., and Kaye, J. P. (2015). Topographic controls on the depth distribution of soil CO2 in a small temperate watershed. Applied Geochemistry, 63, 58-69.
Type: Journal Articles Status: Published Year Published: 2015 Citation: Finney, D. M., White, C. M., & Kaye, J. P. (2015). Biomass Production and Carbon/Nitrogen Ratio Influence Ecosystem Services from Cover Crop Mixtures. Agronomy Journal.
Type: Journal Articles Status: Awaiting Publication Year Published: 2015 Citation: Finney, D. M., Eckert, S. E., & Kaye, J. P. (2015). Drivers of nitrogen dynamics in ecologically based agriculture revealed by long-term, high frequency field measurements. Ecological Applications.
Type: Journal Articles Status: Published Year Published: 2015 Citation: Mazzilli, S. R., Kemanian, A. R., Ernst, O. R., Jackson, R. B., & Pi�eiro, G. (2015). Greater humification of belowground than aboveground biomass carbon into particulate soil organic matter in no-till corn and soybean crops. Soil Biology and Biochemistry, 85, 22-30.