Source: NORTH CAROLINA STATE UNIV submitted to NRP
ASSESSING THE GREENHOUSE GAS MITIGATION POTENTIAL OF ORGANIC SYSTEMS IN THE SOUTHEAST
Sponsoring Institution
National Institute of Food and Agriculture
Project Status
COMPLETE
Funding Source
OTHER GRANTS
Reporting Frequency
Annual
Accession No.
0230561
Grant No.
2012-51106-20332
Cumulative Award Amt.
$742,583.00
Proposal No.
2012-02978
Multistate No.
(N/A)
Project Start Date
Sep 1, 2012
Project End Date
Aug 31, 2016
Grant Year
2013
Program Code
[112.E]- Organic Transitions
Recipient Organization
NORTH CAROLINA STATE UNIV
(N/A)
RALEIGH,NC 27695
Performing Department
Plant Pathology
Non Technical Summary
Agricultural lands provide potential opportunities for climate change mitigation through promoting soil C sequestration and reducing N2O emissions. Agriculture is one of the few economic sectors that can be adapted to have a net negative impact on greenhouse gas emissions. It is assumed that high organic inputs in organic systems provide best opportunities for C sequestration and N retention in the Southeast coastal plains. Still, the relative scarcity of field data makes any generalizations across organic systems and regions difficult. The key to understanding how agriculture will both adapt to climate change and mitigate greenhouse gas emissions is to understand how cropping systems impact the C and N cycles and identify management regimes that are not only profitable, but also optimize soil C sequestration and reduce N losses. The long-term goal of this integrated research, education and extension project is to understand the impact of organic systems in the Southeastern US on greenhouse gas emissions and educate stakeholders and students about maximizing the mitigation potential of these systems. Our supporting objectives are to 1) investigate how organic systems affect soil carbon (C) and nitrogen (N) dynamics and greenhouse gas emissions, 2) examine how tillage practices and cover crops can be integrated to enhance C sequestration and reduce N2O emissions, and 3) educate next generation of organic researchers and farmers through student training and various outreach activities. We propose that organic systems with reduced tillage may provide the best opportunities to increase soil C sequestration and reduce soil N2O emission in the sandy soils of the warm and humid Southeastern USA. Our central hypothesis is that integration of high organic matter inputs and reduced tillage is the key to tighten C and N cycles and reduce N2O emission.We plan to utilize three certified organic systems and three parallel conventional systems at our existing long-term site at Goldsboro, NC to conduct a series of field experiments to quantify the CO2 and N2O emissions and to identify potential mechanisms underlying the C and N stabilization in soil. We also plan to develop new curricula on greenhouse gases and agriculture for student training and stakeholders. Outcomes of this project would provide essential data necessary for developing organic practices that reduce soil N2O emissions while increasing C sequestration.
Animal Health Component
40%
Research Effort Categories
Basic
60%
Applied
40%
Developmental
(N/A)
Classification

Knowledge Area (KA)Subject of Investigation (SOI)Field of Science (FOS)Percent
1010110107040%
1024099107030%
1022410106030%
Knowledge Area
102 - Soil, Plant, Water, Nutrient Relationships; 101 - Appraisal of Soil Resources;

Subject Of Investigation
4099 - Microorganisms, general/other; 0110 - Soil; 2410 - Cross-commodity research--multiple crops;

Field Of Science
1060 - Biology (whole systems); 1070 - Ecology;
Goals / Objectives
Goals/Objectives: The long-term goal of this integrated research, education and extension project is to understand the impact of organic systems in the Southeastern US on greenhouse gas emissions and educate stakeholders and students about maximizing the mitigation potential of these systems. Our supporting objectives are to 1) investigate how organic systems affect soil carbon (C) and nitrogen (N) dynamics and greenhouse gas emissions, 2) examine how tillage practices and cover crops can be integrated to enhance C sequestration and reduce N2O emissions, and 3) educate the next generation of organic agriculture researchers and farmers through student training and an active, multi-pronged outreach program. Our interdisciplinary team will approach five specific objectives through experiments and field demonstration on farm-scale, replicated certified organic plots at our existing long-term experimental site at Center for Environmental Farming, Goldsboro, NC. Objective 1: Quantify the greenhouse gas emissions and soil C and N in three organic and tillage management regimes and three paralleled conventional systems. Objective 2: Determine the impact of invertebrates on residue decomposition and soil C stabilization. Objective 3: Assess the effects of AM fungi on soil aggregation and N retention in organic systems. Objective 4: Ascertain the role of cover crops and weeds in mediating soil N availability Objective 5: Education and outreach through developing new curricula on greenhouse gases and agriculture for student training and stakeholders. Expected Outputs: This project will create knowledge on the differences in C and N cycling between organic and conventional systems and elucidate which biological factors are primarily responsible for those differences. In addition we hope to have short term and longer term impacts in several sectors. The educational curriculum developed will be used throughout the region and will serve as a model for others. Our research group has excellent ties with the regional NRCS training center located in Greensboro, NC that serves 22 states. CEFS data has been used in previous updates to the RUSLE2 model that guides how NRCS field offices share costs with farmer for soil conserving processes. During our training events with NRCS, we will engage them on how this information could be incorporated in their "Greenhouse Gas Emissions Resource" metric which they have deployed as part of their online "Fieldprint Calculator". This tool calculates a farms direct and embedded impact on greenhouse gas emissions. N2O emissions are only projected for rice systems. Our data could be used to expand the N2O projections to other crops based on organic versus conventional status, the amount of tillage involved, and the length of the rotation. This tool will also be the likely arbiter of any greenhouse gas payments to farmers that have been discussed by USDA.
Project Methods
We will conduct a series of experiments and education programs using our existing long-term field site based at the Center for Environmental Farming Systems near Goldsboro, North Carolina to achieve five specific objectives. Objective 1: Quantify the greenhouse gas emissions and soil C and N in three organic and tillage management regimes and three paralleled conventional systems. We will quantify the C and N distribution across the soil profile and monitor the temporal dynamics of labile N pools. Intensive measurements of N2O and CO2 will be conducted. We will also quantify soil and microbial parameters to understand the possible links among soil and microbial properties, GHG emissions, soil C and N dynamics, and plant N utilizations. Objective 2. Determine the impact of soil invertebrates on residue decomposition and soil C stabilization. To evaluate invertebrate impacts on cover crop litter decomposition and nutrient cycling, litter will be placed in bags deployed in the experimental plots. Objective 3. Characterize mycorrhizal effects on soil aggregation and plant N acquisition. We will use a mycorrhizal bioassay to assess mycorrhizal-mediated plant N uptake both in field and greenhouse experiments. We will also quantify the soil aggregates fractions through wet-sieving into aggregates of different size and assess AM fungal contribution of soil N translocations in field with root and mycorrhizal hyphal ingrowth cores. Objective 4. Assess the impact of cover crops and weeds on soil C and N sequestration and soil GHG emissions. Weeds and cover crops will be intensively sampled to assess their capacity for N retention and organic C inputs. Objective 5. We will approach our education and outreach goals through a) developing an extension curriculum on greenhouse gases and agriculture to deliver to local and national audiences, and b) developing education curricula on agriculture and climate change for undergraduate and graduate student training.   Result synthesis and evaluation: Results obtained will be synthesized to assess how different soil amendments (either cover crops or other organic materials) affect soil C sequestration and N2O emissions. Our proposed experiments should: 1) determine if tightening nutrient cycling through organic inputs and cover cropping favor C sequestration and biological N retention to reduce N2O emissions, and 2) determine if enhancement of microbial biomass and activities and soil biodiversity through cover crops and soil amendments improves soil quality (aggregation) and soil C stabilization. Results from this work and our protocols will also be evaluated through the scientific review process when we submit publications and when we present at scientific meetings. Also, results will be delivered to growers and other related stakeholders through our extension talks and written and electronic materials. In addition, we are members of the Center for Environmental Farming Systems at NCSU team and as such we have an internal evaluation process among the main faculty members and with stakeholders.

Progress 09/01/12 to 08/31/16

Outputs
Target Audience:Students: Three graduate students received supports or partially supports from this project to conduct field and lab experiments to assessing the effects of different organic management practices on soil C and N dynamics and greenhouse gas emissions. Multiple visiting scientists, including one visiting postdoctoral scholar, were also involved and got trained through this project, although they did not receive financial supports from this project. The scientific community in general, particularly ecologists, soil scientists, and biologists and graduate and undergraduate students. Our project was presented at the "French-American Climate Change Symposium" (Raleigh, NC, August 27, 2015. 220 attendees). Our graduate students presented multiple talks at regional and national meetings (for example, ASA-CSSA-SSSA International Annual meetings in Minneapolis, November, MN 2015, and Phoenix, AZ, November 2016). Oral Presentation. Nov 2016. Scientists from multiple countries (including a delegate from Nanjing Agricultural University, Nanjing, China) visited our field project and the automatic detection systems for N2O at the Center for Environmental Farming Systems (CEFS, Goldsboro, NC). Farmers and land managers. Co-PIs and students made multiple presentations at the field days. On the Field Day, farmers and land managers visited our field project for automatic N2O measurement. ? Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?Six graduate students were trained: This project provided funding fully or partially supporting the research for three PhD (Alexandra Knight, Crop Science; Sean Bloszies, Soil Ecology; Yunpeng Qiu, SoilEcology) and three MS students (Paul Adams, Entomology; Natalie Ross, Soil Science; Peyton Ginakes, Soil Science). Two exchange PhD students were actively involved and conducted experiments associated with this project (Yi Zhang and Keke Wu, both in Plant Pathology Dept., North Carolina State University). Three visiting scientists received training through participating in field sampling and conducting independent research (Dr. Xuelin Zhang, Henan Agricultural University, China; Dr. Bhoopander Giri, University of Delhi, India; Jinping Wang, Central China Agricultural University, China). Fifteen graduate students taught: Six graduate students at NCSU were enrolled in our Climate Change and Agriculture course from 4 NC State academic departments. Nine graduate students were enrolled in our Ecology of Soil Ecosystems course from five NCSU academic departments. Many visiting faculty also regularly attended our courses. Farmers: Farmers were directly impacted by the presentations at our annual Field Days at CEFS, Goldsboro and a special farmer-researcher event "Soil Bration" on October 17, 2014, as well as by presentations listed under 'Products - Publications' and 'Products - Events', with eight presentations geared toward farmers or extension personnel presented over the life of the project.? How have the results been disseminated to communities of interest?Results of this project have been disseminated in multiple diverse ways. First, two peer-reviewed manuscripts and four thesis/dissertations have been published or submitted. Four other manuscripts have been either submitted or under review for peer-reviewed journals and six more are under preparation for publication. Over twenty presentations (posters or talks) have been given at a national or regional level to reach scientific audiences at different scientific meetings (such as International Annual of ASA-CSSA-SSSA and Annual meeting of Ecological Society of America). Also, our project and results of our work were shared at our annual Field Day at CEFS, Goldsboro, NC. It was shared and extensively discussed at the Soil Bration on October 17, 2014, an event organized by the Center for Environmental Farming Systems and the USDA Natural Resources Conservation Service. Over 300 farmers, land managers, and scientists attended this event. We also shared our research at the "Sustaining agriculture in a changing climate. French-American Climate Change Symposium" (Raleigh, NC, August 27, 2015. 220 attendees). What do you plan to do during the next reporting period to accomplish the goals? Nothing Reported

Impacts
What was accomplished under these goals? Summary of overall project: This project assessed soil N2O emissions in the coastal Southeast US plain, using six conventional (3) and organic (3) systems that have been under contrasting tillage and cover cropping practices over the last 15 years, and examined the relationships between the N2O emissions and soil C, N and microbial parameters. One of our most striking findings was that regardless of conventional or organic systems, small changes in management practices can have large impacts on greenhouse gas emissions from soil. In particular, tillage and fertilizer placement were found to have major impacts on N2O emissions. Another surprising finding was that applications of some herbicides significantly affected N2O emissions. Also, arbusular mycorrhizal fungi were shown to have high C use efficacy in reducing N2O emissions and transferring soil N to host plants. In addition, our project provided unique opportunities for student training. It provided partially financial supports for three PhD and three MS students, and created a platform in which two exchange PhD students and multiple visiting scholars actively participated. The project and results obtained were timely incorporated into two courses for graduate students (Ecology of Soil Ecosystems; Agriculture and Climate Change). The field project was also presented extensively to diverse audiences of farmers and land managers as well as the scientific community in general. Objective 1: Quantify the greenhouse gas emissions and soil C and N in three organic and tillage management regimes and three paralleled conventional systems. We conducted four sets of field, greenhouse and lab experiments examining N2O emissions from organic and conventional systems located at the Center for Environmental Farming Systems, Goldsboro, NC. First, we monitored N2O emissions following every rainfall event for three years (from early 2013 to later 2015), using the static chamber method, and for the first time, generated a comprehensive long-term dataset of N2O emissions in the coastal Southeast US plain; Second, we examined whether weed growth in the early growth season suppressed N2O emissions and assessed whether and how applications of herbicides (18 chemicals) affected soil N2O emissions (Knight, 2016, PhD Dissertation, North Carolina State University). Third, we conducted a greenhouse experiment assessing the impact of corn roots and their associate mycorrhizal fungi on soil N2O emissions in both organic and conventional soils (Zhang et al. 2016). Fourth, multiple incubation experiments were carried out to quantify the N2O and CO2 emissions from organic and conventional soils as influenced by different C and N availability following cover crop incorporation or crop harvesting (Sean Bloszies, 2016, PhD Dissertation, North Carolina State University). Fifth, we have developed a simple robust continuous monitoring system for N2O emissions to assess the temporal variability in emissions (Ross, 2016, MS Thesis, North Carolina State University). Objective 2: Determine the impact of invertebrates on residue decomposition and soil C stabilization. Field pitfall traps were installed in April 2013 and soil arthropods had been collected continuously for two years. Overall, the abundances and diversity of arthropods decreased with the increasing perturbation intensity and frequencies, leading to highest arthropod abundance and diversity in the organic reduced-till system and lowest in the conventional clean-till one (Adams, 2015, MS thesis, North Carolina State University). These data were also correlated well with microbial biomass and activities. Objective 3: Assess the effects of AM fungi on soil aggregation and N retention in organic systems. We found that mycorrhizal infection of both corn and soybean roots tended to be lower in organic than conventional soils. However, a greenhouse experiment that assessed mycorrhizal effects on N2O emissions showed that mycorrhizal fungi significantly reduced N2O emissions in organic soils but had no effects in conventional soils with high N inputs (Zhang et al. 2016), suggesting that infection rate may have underestimated the contribution of mycorrhizal fungi in N retention. In addition, our results showed that mycorrhizal fungi used marginal organic carbon to significantly enhanced plant N uptake and reduced denitrification, demonstrating their high energy use efficacy. Objective 4: Ascertain the role of cover crops and weeds in mediating soil N availability: We found that cover cropping critically modulated soil N availability. Both the type and the biomass of cover crops significantly affected the soil N and cover crop biomass N that would subsequently be available for the major crop. Also, we examined whether weed growth in the early growth season suppressed N2O emissions and assessed whether and how applications of herbicides (18 chemicals) affected soil N2O emissions (Knight, 2016, PhD Dissertation, North Carolina State University). Our results showed that weeds can substantially retain N in their biomass at the very early stage of crop growing season. What was really surprising was that applications of several herbicides significantly affected soil N transformations and N-transforming microbes. The exact mechanisms are unclear but we will continue to explore the underlying mechanisms. Objective 5: Education and outreach through developing new curricula on greenhouse gases and agriculture for student training and stakeholders. Please below "opportunities provided for training and professional development".

Publications

  • Type: Theses/Dissertations Status: Published Year Published: 2016 Citation: Knight, Alexandra Marie. 2016. Greenhouse Gas Emissions in Long Term Agricultural Production Systems. Ph.D., NORTH CAROLINA STATE UNIVERSITY, 2016, 104 pages; 10289909. gradworks.umi.com
  • Type: Theses/Dissertations Status: Submitted Year Published: 2016 Citation: Blosvzies, Sean A. 2016. Soil Microbial Activity and Organic Carbon Dynamics in Low Input Agroecosystems. PhD dissertation. North Carolina State University.
  • Type: Journal Articles Status: Submitted Year Published: 2016 Citation: Bloszies, S. A., J. Grossman, J. Heitman, S. Hu. 2016. Effects of legume cover crops and spring termination practices on soil C dynamics in an organic system in the Southeastern U.S.. Soil & Tillage Research.
  • Type: Journal Articles Status: Accepted Year Published: 2016 Citation: Wu, K.K., D. M. Chen, C. Tu, Y. P. Qiu, K. O. Burkey, S. C. Reberg-Horton, S. L. Peng, Shuijin Hu. 2016. CO2-induced alterations in plant nitrate utilization and root exudation stimulate N2O emissions. Soil Biology & Biochemistry.
  • Type: Journal Articles Status: Under Review Year Published: 2016 Citation: Zhang, X. L., C. Tu, Y.P. Qiu, S.C. Reberg-Horton and S. Hu. 2016. High carbon use efficiency in arbuscular mycorrhizal fungi for reducing soil N2O emissions. Global Change Biology.
  • Type: Journal Articles Status: Under Review Year Published: 2016 Citation: Knight, A. M., W. J. Everman, S. Chris Reberg-Horton, C. Tu, W. Robarge, N. Ross, S. Bloszies, M. A. Cavigelli, Y. P. Qiu. M. Schroeder-Moreno, S. Hu. 2016. Greenhouse gas emissions in long-tern conventional and organic farming systems in Southeast US. Global Change Biology.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2016 Citation: Bloszies, S.A., C. Reberg-Horton, S. Hu. Effects of Alternative Farming Systems on Soil Organic Matter Pools and Nitrous Oxide Emissions. International Annual meeting of ASA-CSSA-SSSA, Phoenix, AZ. Oral Presentation. Nov 2016.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2016 Citation: Qiu YP, Y. Jiang, K.O. Burkey, R. W. Zobel, H.D. Shew, S. Hu. 2016. Effects of arbuscular mycorrhizal fungi on organic carbon decomposition under elevated temperature and ozone conditions. The 101th Ecological Society of America Annual Meeting, August 11, 2016. Fort Lauderdale, FL, USA
  • Type: Conference Papers and Presentations Status: Published Year Published: 2015 Citation: Knight, A.M., S. Reberg-Horton, W.J. Everman, S. Hu, D.L. Jordan, and N. Creamer. Nitrous oxide Emissions in long term cropping systems. 2015. ASA-CSSA-SSSA. 342-15.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2016 Citation: Knight, A.M., W.J. Everman, S. Reberg-Horton, S. Hu, D.L. Jordan, and N. Creamer. 2016. Nitrous oxide Emissions in long term cropping systems. Northeastern Plant, Pest, and Soils Conference. 1(70).
  • Type: Conference Papers and Presentations Status: Published Year Published: 2016 Citation: Knight, A.M., W.J. Everman, S. Reberg-Horton, S. Hu, D.L. Jordan, and N. Creamer. 2016. Herbicide and nitrogen applications impact nitrous oxide emissions. Northeastern Plant, Pest, and Soils Conference. 1(156).
  • Type: Conference Papers and Presentations Status: Published Year Published: 2016 Citation: Knight, A.M., W.J. Everman, S. Reberg-Horton, S. Hu, D.L. Jordan, and N. Creamer. 2016. Herbicide and nitrogen applications impact nitrous oxide emissions. WSSA. 56(69).
  • Type: Conference Papers and Presentations Status: Published Year Published: 2016 Citation: Knight, A.M., W.J. Everman, S. Reberg-Horton, S. Hu, D.L. Jordan, and N. Creamer. 2016. Impact of weed management systems on nitrous oxide emissions. SWSS. 69(283).


Progress 09/01/14 to 08/31/15

Outputs
Target Audience:Students: Five graduate students received supports or partially supports from this project to conduct field and lab experiments to assessing the effects of different organic management practices on soil C and N dynamics and greenhouse gas emissions. Multiple visiting scientists were also involved and got trained through this project, although they did not receive financial supports from this project. The scientific community in general, particularly ecologists, soil scientists, and biologists and graduate and undergraduate students. Co-PI, Chris Reberg-Horton, co-organized the symposium "Sustaining agriculture in a changing climate. French-American Climate Change Symposium". (Raleigh, NC, August 27, 2015. 220 attendees). Our graduate students presented multiple talks at regional and national meetings. Farmers and land managers. Co-PIs made multiple presentations at the field days. PI (Hu), multiple graduate students and technicians presented their projects in field for "SOILbration: 20th anniversary for the Center for Environmental Farming Systems" (October 17, 2014. 300 attendees). Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?Over the last 12 months, our project provides opportunities to five graduate students: Miss Alexandra Knight (Crop Science) has been assessing the effects of weed growth and herbicides on N cycling and N2O emission. Mr. Paul Adams (Entomology) investigated the effects of farming practices on the soil arthropod community and foliar arthropods. Miss Natalie Ross (Soil Science) is exploring a new approach for measuring N2O emissions using a new continuously measuring method in field. Sean Blosvies (Soil Ecology) and Yunpeng Qiu (Soil Ecology) have been examining the linkages among soil microbial biomass and activities, soil labile C and N, and soil CO2 and N2O emissions through incubation experiments. Also, Dr. Xuelin Zhang (a visiting scholar from Henan Agricultural University, China) receives training in N2O emissions as influenced by labile C and N in organic and conventional corn systems. In addition, Dr. Cong Tu is coordinating the field execution of the project and the trace gas emission measurements. Ms. Dolly Watson and Dr. Bhoopander Giri (a visiting scholar from University of Delhi, India) examined the effect of mycorrhizal fungi on soil residue decomposition and N transfer. Two technicians (Mr. Tomas Moreno and Mr. Evan Taylor), who are financially supported by North Carolina Department of Agriculture, also received training in field experimental design and greenhouse gas sampling. Finally, multiple undergraduate students participated in this project through working on sample analyses in lab and/or field management or soil and plant sampling. How have the results been disseminated to communities of interest?Our project and results of our work were shared at the Soil Bration on October 17, 2014, an event organized by the Center for Environmental Farming Systems and the USDA Natural Resources Conservation Service. Over 300 farmers, land managers, and scientists attended this event. We also shared our research at the "Sustaining agriculture in a changing climate. French-American Climate Change Symposium". (Raleigh, NC, August 27, 2015. 220 attendees). We have presented our results at six different scientific meetings and more results will be presented at the ASA, CSSA, and SSSA annual meetings in Minniapolis, MN in this coming November. In addition, the Project Director attended the Annual Project Director meeting in DC in October, 2015 and had an oral presentation that highlighted the project progress. In summary, one thesis and seven meeting abstracts were published. What do you plan to do during the next reporting period to accomplish the goals?Research & Education Program: We have requested one-year no-cost extension for our project. We are in the process analyzing results from our multiple experiments that addressed our three long-term goals in understanding the effects of organic systems, cover crops and tillage on soil C and N dynamics and greenhouse gas emissions. In particular, we will carefully build the linkages among soil C and N, microbial activities and soil N2O and CO2 emissions. Using stable isotope techniques, we will finish an ongoing greenhouse experiment that assesses mycorrhizal effects on N2O emissions from conventional and organic soils. We will strive to construct a conceptual model based on a large dataset of N2O emissions as influenced by fertilization practices, tillage and soil physiochemical and biological factors. Five manuscripts for peer-reviewed journals are in internal review or in preparation and will be submitted in this coming winter or Spring, 2016. We will continue to train four graduate students. We will also introduce this project to students to the Soil Ecology class the PD will teach in Spring, 2016. Six to eight manuscripts will be submitted to peer-reviewed journals. Outreach program: We will use the Field day at the CEFS in July 2016 as a platform to show the significance of farming practices in controlling soil C and N dynamics and greenhouse gas emissions. This is one of our major field events and attracts ca. 300 participants. Also, results of our work will continue to be again shared at the annual Organic Grains Field Day on July 30th and the annual Organic Commodities and Livestock Conference held each February. We will present our results at the ASA, CSSA, and SSSA annual meetings (November 2016) and at the Ecological Society of America annual meeting (August, 2016).

Impacts
What was accomplished under these goals? In the last 12 months, we continued multiple field, greenhouse and incubation experiments to approach the objectives of our research project. Trace gas emissions: Continuous measurements of nitrous oxide (N2O) emission study were performed in six different farming systems with three replicates at Center for Environmental Farming Systems (CEFS), Goldsboro, NC. These systems include Organic clean-till, Organic reduced-till, Organic long-rotation, Conventional clean-till, Conventional no-till, and Conventional long-rotation. A static gas chamber technique was employed to collect N2O emitted from soils. Gas sampling started right after corn seeds were sowed, and takes place 24-48 hours after every rainfall event greater than 0.5 inch within 24 hours. In general, N2O flux rates tended to be higher in the conventional clean-till system than conventional no-till and organic-reduced till systems, with the N2O emission rate being nearly twice much in the former than in the two systems. We also measured the direct effect of multiple herbicides on N2O emissions in incubation experiments. In addition, Co-PI, Wayne Robarge, and his graduate student, Natalie Gross, established a continuous N2O measurement system in the field at CEFS. Soil carbon and nitrogen dynamics: We continued analyzing soil samples collected before planting and during the growing season to monitor the soil C and N dynamics, in particular, the labile C and extractable N. In general, organic C, particularly labile C was higher in organic than conventional systems, but extractable N was strongly affected by organic or mineral N inputs, which was closely related to N2O emissions. The duration of each farming practice also affected the dynamics of soil labile C and N and microbes. Soil C dynamics and mycorrhizal fungi: We found that mycorrhizal infection of both corn and soybean roots tended to be lower in organic than conventional soils. However, a greenhouse experiment that assessed mycorrhizal effects on N2O emissions showed that mycorrhizal fungi significantly reduced N2O emissions in organic soils but had no effects in conventional soils with high N inputs, suggesting that infection rate may have underestimated the contribution of mycorrhizal fungi in N retention. The soil arthropod community structure: field pitfall traps were installed in April 2013 and soil arthropods have been collected continuously since. Overall, the abundances and diversity of arthropods decrease with the increasing perturbation intensity and frequencies, leading to highest arthropod abundance and diversity in the organic reduced-till system and lowest in the conventional clean-till one. These data were also correlated well with microbial biomass and activities.

Publications

  • Type: Conference Papers and Presentations Status: Published Year Published: 2015 Citation: Knight, A. M., W.J. Everman, S. Reberg-Horton, S. Hu, D.L. Jordan and N. Creamer. 2015. Nitrous Oxide Emissions Impacted by Weed Management. Southern Weed Sci. Soc. 68: 133.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2015 Citation: Knight, A. M., W.J. Everman, S. Reberg-Horton, S. Hu, D.L. Jordan and N. Creamer. 2015. Effect of Weed Management on Nitrous Oxide Emissions in North Carolina Cropping Systems. Proc. NorthEastern Weed Sci. Soc. 69:44.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2014 Citation: Bloszies, S.A., Grossman, J.M. and Hu, S. Effect of legume cover crops and spring termination practices on soil C dynamics in an organic system. 2014 Soil Science Society of America Annual Meeting. Long Beach, CA (Nov 4, 2014).
  • Type: Conference Papers and Presentations Status: Published Year Published: 2015 Citation: Bloszies, S.A., Ginakes, P., and Hu, S. Soil conservation and greenhouse gas emissions: The role of reduced tillage and organic agriculture in soil nitrous oxide production. 2015 Soil and Water Conservation Society Conference. Greensboro, NC (July 28, 2015).
  • Type: Conference Papers and Presentations Status: Accepted Year Published: 2015 Citation: Bloszies, S.A. Reberg-Horton, S.C., and Hu, S. The Role of Reduced Tillage and Organic Agriculture in Soil Nitrous Oxide Emissions. 2015 Soil Science Society of America Annual Meeting. Minneapolis, MN (November 15, 2015).
  • Type: Theses/Dissertations Status: Published Year Published: 2015 Citation: Paul R. Adams III. 2015. Soil and foliar arthropod abundance and diversity in five cropping systems in the Southeastern United States. MS Thesis. North Carolina State University.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2014 Citation: Knight, A. M., W.J. Everman, S. Reberg-Horton, S. Hu, D.L. Jordan and N. Creamer. 2014. Impact of Long Term Production Systems On Greenhouse Gas Emissions. Proc. of Amer. Soc. of Agron. 61:15.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2015 Citation: Knight, A. M., S. Reberg-Horton, W.J. Everman, S. Hu, D.L. Jordan and N. Creamer. 2015. Nitrous Oxide Emissions in Long Term Cropping Systems. Proc. of Amer. Soc. of Agron. 342: 15.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2015 Citation: Knight, A. M., W.J. Everman, S. Reberg-Horton, S. Hu, D.L. Jordan and N. Creamer. 2015. Nitrous Oxide Output Based on Weed Management Systems. Proc. Weed Sci. Soc. of Amer. 55:119.


Progress 09/01/13 to 08/31/14

Outputs
Target Audience: 1. The scientific community in general, particularly ecologists, soil scientists, and biologists 2. Graduate and undergraduate students in agriculture- and environment-related areas. 3. Farmers and land managers. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? Over the last 12 months, our project provides opportunities to six graduate students: Miss Alexandra Knight (Crop Science) has been assessing the effects of weed growth on N cycling and N2O emission. Mr. Paul Adams (Entomology) is working on soil arthropod community. Miss Natalie Ross (Soil Science) is exploring a new approach for measuring N2O emissions using a new continuously measuring method in field. Sean Blosvies (Soil Ecology), Peyton Ginakes (Soil Sciences) and Yunpeng Qiu (Soil Ecology) have been examining the linkages among soil microbial biomass and activities, soil labile C and N, and soil CO2 and N2O emissions. Also, Dr. Xuelin Zhang (a visiting scholar) receives training in N2O emissions as influenced by labile C and N in organic and conventional corn systems. In addition, Dr. Cong Tu is coordinating the field execution of the project and the trace gas emission measurements. Ms. Dolly Watson is working on mycorrhizal fungi and soil aggregation. Two technicians (Mr. Tomas Moreno and Mr. Evan Taylor), who are financially supported by North Carolina Department of Agriculture, also received training in field experimental design and greenhouse gas sampling. Finally, multiple undergraduate students participated in this project through working on sample analyses in lab and/or field management or soil and plant sampling. How have the results been disseminated to communities of interest? Our project and results of our work were shared at the annual Organic Grains Field Day on July 30th, 2014 and the annual Organic Commodities and Livestock Conference held in February, 2014. We have presented our results atfour different scientific meetings and more results will be presented at the ASA, CSSA, and SSSA annual meetings in Minniapolis, MN in this coming November. We will show our field project to the participants of the Soil Bration on October 17, 2014, an event organized by the Center for Environmental Farming Systems and the USDA Natural Resources Conservation Service. About 500 farmers, land managers, and scientists will attend this event. In summary, one paper andfour meeting abstracts were published andanother meeting abstracthas beenaccepted. What do you plan to do during the next reporting period to accomplish the goals? Research Program: We will continue to carry out the multiple experiments to address our three long-term goals in understanding the effects of organic systems, cover crops and tillage on soil C and N dynamics and greenhouse gas emissions. In particular, our team will carefully approach all the five specific objectives listed in our proposal and conduct experiments to identify the underlying mechanisms that mediate the effects of soil C and N and microbial activities on soil N2O and CO2 emissions. Using stable isotope techniques, we are in the process of designing or carrying out both lab incubation and greenhouse experiments to assess N2O emissions from conventional and organic soils. We plan to manipulate arbuscular mycorrhizal fungi to determine their impact on N2O emissions via two potential contrasting mechanisms, labile C inputs or N removal. So far, we have generated a large dataset of N2O emissions as influenced by fertilization practices, tillage and soil physiochemical and biological factors. We plan to publish these data in multiple manuscripts for peer-reviewed journals. Outreach program: We will use the Soil Bration event in October as a platform to show the significance of farming practices in controlling soil C and N dynamics and greenhouse gas emissions. Also, results of our work will continue to be shared at the annual Organic Grains Field Day on July 30th and the annual Organic Commodities and Livestock Conference held each February. We will present our results at the ASA, CSSA, and SSSA annual meetings and at the Ecological Society of America annual meeting. We will introduce our project and share our results to the participants of the annual CEFS Field Day, an event that regularly attracts ca. 300 participants.

Impacts
What was accomplished under these goals? In the last 12 months, we conducted multiple field, greenhouse and incubation experiments to approach the objectives of our research project. Trace gas emissions: Nitrous oxide (N2O) emission study was performed in six different farming systems with three replicates starting in April, 2013 at Center for Environmental Farming Systems (CEFS), Goldsboro, NC. These systems include Organic clean-till, Organic reduced-till, Organic long-rotation, Conventional clean-till, Conventional no-till, and Conventional long-rotation. A static gas chamber technique was employed to collect N2O emitted from soils. Gas sampling started right after corn seeds were sowed, and takes place 24-48 hours after every rainfall event greater than 0.5 inch within 24 hours. From April 2013 toAugust 2014, we have sampled45 times.In general, N2O flux rates tended to be higher in the conventional clean-till system than conventional no-till and organic-reduced till systems, with the N2O emission rate being nearly twice much in the former than in the two systems. We also examined whether application of herbicides affect weedy growth and the N2O emission. Following application of PRE herbicides, no significant differences were observed in N2O emissions between the weedy versus weed free plots both in 2013 and 2014, likely due to the lack of significant weed growth. Soil carbon and nitrogen dynamics: We collected soil samples right before planting and continued the sampling periodically to monitor the soil C and N dynamics, in particular, the labile C and extractable N. In general, organic C, particularly labile C was higher in organic than conventional systems, but extractable N was strongly affected by organic or mineral N inputs. The duration of each farming practice also affected the dynamics of soil labile C and N and microbes. Weed treatments through herbicides did not significantly affect soil extractable and mineralizable N. In addition, a lab incubation experiment showed that soil N2O emissions were higher in the conventional till system than other ones. Soil C dynamics and mycorrhizal fungi: Soil, and corn and soybean root samples have been collected for measurement of external fungal hyphal, root colonization and soil aggregate stability measurements from the first two sampling times of 4 weeks and 8 weeks post corn germination. Surprisingly, mycorrhizal infection of both corn and soybean roots tended to be lower in organic than conventional soils. However, a greenhouse experiment that assessed mycorrhizal effects on N2O emissions showed that mycorrhizal fungi significantly reduced N2O emissions in organic soils but had no effects in conventional soils with high N inputs. The soil arthropod community structure: field pitfall traps were installed in April 2013 and soil arthropods have been collected continuously since. Interestingly, arthropod abundance was highest in the conventional no-till system and lowest in the conventional-clean till one. The exact implications of these data are unclear and we plan to examine how these differences in abundance affect residue decomposition in this coming year.

Publications

  • Type: Conference Papers and Presentations Status: Published Year Published: 2014 Citation: A.M. Knight, W.J. Everman, S. Reberg-Horton, and S. Hu. 2014. IMPACT OF WEED MANAGEMENT SYSTEMS ON GREENHOUSE GAS EMISSIONS. Proc. NorthEastern Weed Sci. Soc. 68:32.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2014 Citation: A.M. Knight, W.J. Everman, S. Reberg-Horton, and S. Hu. 2014. IMPACT OF WEED MANAGEMENT SYSTEMS ON GREENHOUSE GAS EMISSIONS. Proc. South. Weed Sci. Soc. 67:47.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2014 Citation: A.M. Knight, W.J. Everman, S. Reberg-Horton, and S. Hu. 2014. IMPACT OF WEED MANAGEMENT SYSTEMS ON GREENHOUSE GAS EMISSIONS. Proc. Weed Sci. Soc. Amer. 54:300.
  • Type: Conference Papers and Presentations Status: Accepted Year Published: 2014 Citation: A.M. Knight, W.J. Everman, S. Reberg-Horton, and S. Hu, D.L. Jordan and N. Creamer. 2014. IMPACT OF LONG TERM PRODUCTION SYSTEMS ON GREENHOUSE GAS EMISSIONS. Proc. of Amer. Soc. of Agron.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2014 Citation: X.L. Zhang, C. Tu, Y.P. Qiu, S.C. Reberg-Horton and S. Hu. 2014. Arbuscular mycorrhizal fungi markedly reduce N2O emissions from an organic soil. 99th Annual meeting of Ecological Society of America. Sacramento, August 10-15, 2014.
  • Type: Journal Articles Status: Published Year Published: 2014 Citation: Y. Wang, Wen Xia Duan, C. Tu, S. Washburn, L Cheng and S. Hu. 2014. Soil carbon, nitrogen and microbial nynamics of pasturelands: Impacts of grazing intensity and planting systems. Pedosphere 24: 408-416.


Progress 09/01/12 to 08/31/13

Outputs
Target Audience: The scientific community that includes agronomists, soil scienctists, ecologists, and researchers in the related areas; The organic community that includes organic growers, students and the public who are interested in organic production of foods. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? We have quickly assembled a strong team for the project through which multiple technicians and graduate students have received training. Dr. Cong Tu is coordinating the field execution of the project and the trace gas emission measurements. Ms. Dolly Watson is working on mycorrhizal fungi and soil aggregation. Two technicians (Mr. Tomas Moreno and Mr. Evan Taylor), who are financially supported by North Carolina Department of Agriculture, have joined the team and managed the field plots. Two highly motivated graduate students have joined the team: Miss Alexandra Knight is responsible for assessing the effects of weeds on N cycling and N2O emission. Mr. Paul Adams is working on soil arthropod community. A third graduate student, Miss Natalie Ross, will join the team in this coming August to determine soil microbial biomass and activities, and soil labile C dynamics. Multiple undergraduate students have been involved. How have the results been disseminated to communities of interest? Our team co-sponsored the event “Farming Strategies in Today’s Changing Climate” in Pittsboro, NC on February 8, 2013. Chris Reberg-Horton led the session on annual crop vulnerabilities in the Southeast and how researchers are responding to climate change. We had over 150 farmers and other agricultural professionals attend the event and participate in the discussion sessions. What do you plan to do during the next reporting period to accomplish the goals? Research Program: We will continue to carry out the multiple experiments initiated recently to address our three long-term goals in understanding the effects of organic systems, cover crops and tillage on soil C and N dynamics and greenhouse gas emissions. In particular, our team will carefully approach all the five specific objectives listed in our proposal and conduct experiments to identify the mechanisms that regulate C and N cycling and retention in organic systems. Outreach program: One outgrowth from the recent climate change conference in NC is a proposed climate response tour. This will be a tour of farms with successful adaptation practices for next summer. Also, results of our work will be shared at the annual Organic Grains Field Day on July 30th and the annual Organic Commodities and Livestock Conference held each February. We will present our results at the ASA, CSSA, and SSSA annual meetings (November, 2014; Long Beach, FL) and at the Ecological Society of America annual meeting (August, 2014; Sacramento, CA). In addition, we plan to submit 2-3 manuscripts for peer-reviewed journals based on results obtained from this project.

Impacts
What was accomplished under these goals? In the first eight months of the project, we prepared our field plots, adjusted the crop rotation and have initiated multiple experiments to approach our objectives: Plot preparation: In fall 2012, we made adjustments in winter crops with different types of cover crops/mixes depending on the treatment: all conventional treatments with wheat, both the organic clean-till and the organic long-rotation with clover and vetch, and the organic reduce-till with clover, vetch, and rye. In the spring of 2013, cover crops were killed about three weeks before planting the corn. Corn planting and fertilization: All treatments were planted with corn on April 17th (organic treatments) and April 18th (conventional plots). All organic treatments received 5 T of chicken litter per acre before planting. The conventional treatments received approximately 75 lb N, 30 lb P, and 50 Ib K per acre when corn was planted. Additional 75 lb N per acre was applied to the conventional plots when the corn was 6 weeks old. Field experiments: a. Trace gas emissions. We have collected gas samples six times since the chambers were installed on the day of planting. We used plastic chambers composed of two main parts: the anchor (bottom part, 29 cm dia) and the top cover, and are water sealed. All chambers anchors were placed in the field the day of planting, ready for the first rain event after planting for the gas sampling. A total of 36 chambers were place in the field, two per plot. Chambers needed to be removed every time machinery for weed control was used in the organic treatments and when N was applied in the conventional treatment. In addition, soil moisture/temperature sensors were installed at 3 and 6 inches deep in all treatments. The field setup of gas chambers for greenhouse gas emissions was an important milestone that allowed us to quantify the emissions of all three greenhouse gases (CO2, CH4 and NO) from the very beginning of the growing season. Also, we set up the gas chromatograph in a lab near the field plots in Goldsboro, NC, which provided convenient access for determinations of GHG gases. b. Soil carbon and nitrogen dynamics: We collected soil samples right before planting and continued the sampling monthly to monitor the soil C and N dynamics, in particular, the labile C and extractable N. Weed treatments have also been established to examine soil extractable and mineralizable N. c. Soil C dynamics and mycorrhizal fungi: Soil and corn root samples have been collected for measurement of external fungal hyphal, root colonization and soil aggregate stability measurements from the first two sampling times of 3 weeks and 7 weeks post corn germination. d. The soil arthropod community structure: field microcosms have been installed and used to collect the soil insects with an objective to build the linkages between soil insects, residue decomposition and N cycling.

Publications