Brief Summary of Minutes of Annual Meeting

Accomplishments by major objectives of the Project:

Objective 1. Gain a more thorough understanding of the influence of macro- and micro-scale ecosystems and landscape properties on soil N dynamics.

Activities have focused on linking soil N dynamics with soil health building practices such as reduced tillage, cover crops, application of organic amendments, improved tile-drainage systems, etc.

Short-term Outcomes:

(A) Glycerin, a byproduct from biodiesel company, showed promise in increasing N use efficiency. When applied to soil, it decreased soil nitrate content and increased N uptake by soil microbes. (B) Biochar, a co-product from pyrolytic conversion of biomass to biofuel, showed promise in increasing N use efficiency when co-applied with synthetic N fertilizer, and the effect varied with types of biochar and the method of application of biochar and synthetic N fertilizer in soil, (C) developed N management guidelines for incorporation of organic soil amendment inputs with fertilizer N, (D) long-term no-tillage management of corn increased N mineralization, but has minor effect on agronomic optimum N rate.

Outputs:

Products in 2019 include: 24 grants, 17 peer-reviewed publications, and 35 presentations at professional meetings and meetings for commodity groups, producers and stakeholders. Please see attachment for details. Multiple graduate and undergraduate students as well as postdocs were trained by project participants.

Activities:

(A) Evaluated the usefulness of organic amendments such as glycerin, biochar, and organic food waste in improving N use efficiency, (B) initiated a research in Iowa on modifying the depth and spacing of sub-surface drainage system to reduce the loss of soil organic C and soil N through drainage, (C) analyzed if long-term tillage can reduce N application rate for corn.

Objective 2. Explore optimization of nitrogen management practices through interrogation of corn nitrogen use efficiency datasets from studies conducted across the North Central region.

Soil N tests are key to achieving efficient use of fertilizers that increase crop productivity while prevent over-application of fertilizer N. However, most soil N tests have limited accuracy in predicting N fertilizer needs for crops. So, 30 soil tests were compared across 56 site-years in the US Midwest.

Short-term Outcomes:

A combination of two soil N tests, 14-d aerobic incubation and 5-min tetraphenyl borate extraction best predicted non-responsive sites in 56 site-years in the Midwest compared to the commonly used pre-side-dress nitrate test, and on average decreased over-application by 40% and under-application by 37%.

Outputs:

Products in 2019 include: 10 grants, 3 peer-reviewed publications, and 06 presentations at professional meetings and meetings for commodity groups, producers and stakeholders. Please see attachment for details. Committee members collaboratively published a peer-reviewed publication on the responsiveness of soil N tests (McDaniel et al., Agronomy Journal,                   DOI: org/10.1002/agj2.20129), https://www.news.iastate.edu/news/2020/03/09/nitrogensoiltest). Multiple graduate and undergraduate students as well as postdocs were trained by project participants.

Activities:

A large data set with 56 site-years of N response trials from the North Central region (dataset

from NC1195 committee) was analyzed for N response of N soil tests and factors that may predict N response.

Objective 3. Develop nitrogen management decision-making tools for crop advisers and growers.

Efforts under this objective included improving the ability to forecast N rate requirements in Iowa and engaging the general public, growers, and crop advisers in learning about N cycling in Iowa agricultural systems and N reduction strategies.

Short-term Outcomes:

Existing N management tools such as maximum return to N rate guidelines in conjunction with preplant or pre-side-dress nitrate tests and manure crediting resulted in adjusting N fertilizer rates that improved profitability of corn production and in many cases reduced N fertilizer application rates.

Outputs:

Products in 2019 include: 6 grants, 5 peer-reviewed publications, and 7 presentations at professional meetings and meetings for commodity groups, producers and stakeholders. Numerous farmers, agronomists, and conservation professionals were educated about N decision making tools at county/regional extension meetings, field days, and conferences.

Activities:

On-farm participatory research trials were conducted at 15 locations in Iowa to evaluate management tools and practices that can be considered adaptive techniques for corn N management.

Milestones:

• Complete on-going research on soil N testing and N response across diverse soils and diverse management practices, the residual effects of long-term N application on soil N supply and crop yield response in corn cropping systems, N rate and tillage effect on corn yield, and organic amendment effect on N use efficiency by September 2020.
• Submit peer-reviewed and extension publications by March 2021.
• Disseminate the research outcomes to peers, producers and other stakeholders in 2020-2021.
• Train undergraduate students, graduate students, and postdocs.
• Prepare and submit grant proposals to advance the science in the coming years.