Source: UNIVERSITY OF ILLINOIS submitted to
ASSESSING THE IMPORTANCE OF FREE-LIVING NITROGEN FIXATION IN ORGANIC SYSTEMS
Sponsoring Institution
National Institute of Food and Agriculture
Project Status
ACTIVE
Funding Source
AFRI COMPETITIVE GRANT
Reporting Frequency
Annual
Accession No.
1027651
Grant No.
2022-67019-36109
Cumulative Award Amt.
$749,349.00
Proposal No.
2021-09196
Multistate No.
(N/A)
Project Start Date
Oct 1, 2021
Project End Date
Sep 30, 2025
Grant Year
2022
Program Code
[A1401]- Foundational Program: Soil Health
Project Director
Mulvaney, R. L.
Recipient Organization
UNIVERSITY OF ILLINOIS
2001 S. Lincoln Ave.
URBANA,IL 61801
Performing Department
Natl. Resources and Env. Sci.
Non Technical Summary
Escalating concerns over food safety and environmental protection have substantially increased consumer demand for organic products. However, these products are often in short supply due to the limited land area under organic production, and also because crop yields tend to be lower than for conventional agriculture. The importance of symbiotic dinitrogen (N2) fixation is readily apparent from the widespread use of legume rotations in organic systems, whereas very little attention has been given to non-symbiotic fixation by free-living bacteria. The latter process would be favored for these systems by the absence of synthetic nitrogen and by frequent cover-cropping that improves soil structure and augments the input of carbon from roots and residues.In the present project, a novel approach will be utilized to assess the diversity (targeted gene sequencing) and abundance (qPCR analysis) of free-living bacteria, along with their functional capacity (15N2 fixation), for a well-established organic rotation. Based on previous investigations documenting the importance of a neutral to alkaline soils with adequate calcium availability, a comparison will be made of microbial communities and free-living N2 fixation (FLNF) with and without certified organic limestone and gypsum amendments. This project addresses all three goals of the Soil Health Program Area, and has potential to provide a simple and cost-effective means to reduce nitrogen limitation in organic production systems. There are implications for enhancing economic profitability for producers, improving the commercial availability of organic products, and protecting air, soil, and water quality.
Animal Health Component
40%
Research Effort Categories
Basic
40%
Applied
40%
Developmental
20%
Classification

Knowledge Area (KA)Subject of Investigation (SOI)Field of Science (FOS)Percent
10201101060100%
Knowledge Area
102 - Soil, Plant, Water, Nutrient Relationships;

Subject Of Investigation
0110 - Soil;

Field Of Science
1060 - Biology (whole systems);
Goals / Objectives
Goals:1. Advance scientific understanding of asymbiotic dinitrogen fixation in organic production systems.2. Improve or maintain soil health, sustainability, and productivity in organic production systems.Objectives:1. Modify and optimize the 15N2 assay method of Smercina et al. (2019) for estimating free-living N2 fixation (FLNF) in rhizospheric soil, with (potential) or without (baseline) the use of a C cocktail, relative to:1a. Incubation period; and1b. C cocktail composition.2. Compare different phases of organic rotation regarding:2a. Diazotrophic abundance and diversity using targeted genes for N2 fixation, nitrification, denitrification, and mineralization; and2b. Functional capacity of FLNF assayed using 15N2.3. Ascertain the potential of liming and the use of gypsum for increasing FLNF under organic management with respect to:3a. The abundance and composition of functional genes targeting N-cycle genes;3b. 15N2-measurements of potential and baseline (no C cocktail) FLNF; and3c. Cereal yields and N accumulation.
Project Methods
Objective 1 will be addressed by modifying and optimizing the 15N2 assay method of Smercina et al. (2019) for estimating free-living nitrogen fixation (FLNF) in rhizospheric soil with (potential) or without (baseline) the use of a C cocktail, relative to incubation period; and C cocktail composition. For Objective 2, a comparison will be made of different phases of organic rotation regarding (a) diazotrophic abundance and diversity using targeted genes for major N-cycle processes; and (b) functional capacity for FLNF assayed using 15N2. The same approach used for Objective 2, will be combined with measurements of cereal yields and N accumulation to investigate the potential of liming and the use of gypsum for increasing FLNF under organic management (Objective 3).

Progress 10/01/23 to 09/30/24

Outputs
Target Audience: Nothing Reported Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?This project provided training opportunities for onepostdoctoral associate, three graduate students, and oneundergraduate worker on incubation setup, GPSoperation, gas analysis, soil and plant sampling, and determination of diverse soil properties. How have the results been disseminated to communities of interest?Results from objective 1 will be orally presented in the ASA, CSA, & SSSA annual meeting in San Antonio, TX in November 2024. Some of the results from the entire project will be presented at the Crop Hour extension event at South Dakota State Universityin January 2025. What do you plan to do during the next reporting period to accomplish the goals?By the end of Sept 2025, at least three peer-reviewed manuscripts will be submitted for publication. More results and additional findings will bepresented in extensionand scientific meetings.

Impacts
What was accomplished under these goals? Objective 1 was completed with data collection, with one manuscript submitted forpeer-reviewed publication and the other in preparation; Objectives 2 and 3 were successfully accomplished in the second growing season except for the harvest sampling. Data was collected and processed for statistical analyses and manuscript preparation.

Publications

  • Type: Journal Articles Status: Submitted Year Published: 2024 Citation: Zhou Q., Mulvaney R.L., & Nunes V.L.N. (2024). Improved method for isotopic measurement of free-living nitrogen fixation. Soil Science Society of America Journal. Under review.


Progress 10/01/22 to 09/30/23

Outputs
Target Audience: Nothing Reported Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?The postdoctoral associate,one of the graduate students, and the undergraduate worker gained experience in GPS operation, gas analysis, soil and plantsampling, and determination of diverse soil properties. How have the results been disseminated to communities of interest? Nothing Reported What do you plan to do during the next reporting period to accomplish the goals?The protocol for estimating free-living N2 fixation will bepresented at a professional meeting and in amanuscript that will be submitted for peer-reviewedpublication. Soil samples will be collected periodically during the 2024 growing season for microbial community analysis and for estimating free-living N2 fixation. At harvest, measurements will be made of grain yield and crop N accumulation.

Impacts
What was accomplished under these goals? Objective 1 was completed with data collection for peer-reviewed publication. Objectives 2 and 3 were successfully accomplished in the first of the two growing seasons involved in this project.

Publications


    Progress 10/01/21 to 09/30/22

    Outputs
    Target Audience: Nothing Reported Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?Training ingas handling techniques for use with the protocol developed has been provided to the postdoctoral associate and a new MS student supported by the project. How have the results been disseminated to communities of interest?A press release regarding the current project was post by the College of ACES at the University of Illinois and is available at:https://aces.illinois.edu/news/grant-funds-study-free-living-nitrogen-fixers-organic-systems. What do you plan to do during the next reporting period to accomplish the goals?The protocol for estimating asymbiotic N2 fixation will be completed and employed with soil samples collected during the 2023 growing season. Soil samples will becollected periodicallyfor microbial community analysis, and measurements will be made ofgrain yield and cropN accumulation.

    Impacts
    What was accomplished under these goals? Regarding Objective 1, a new protocol is under development that involves circulation of labeled 15N2 through a desiccator contaning bulk or rhizospheric soil samples. Current work is focused on optmization of the carbon source, incubation period, and soil moisture content for estimating potential N2 fixation. Following the project timetable for Objectives 2 and 3, subplots were stablished, georeferenced, and amended with gypsum and or limestone as detailed in the proposal.

    Publications