Meta-analyses on Fertilizer Management - Results and Recommendations

Meta-analyses on Fertilizer Management - Results and Recommendations
A Proposal to the 4R Research Fund (Rev. 23Sept2015)

Submitted by: Alison J. Eagle (Duke Univ.), Laura E. Christianson (Univ. of Illinois), Rachel L. Cook (Southern Illinois Univ.), R. Daren Harmel (USDA-ARS), and Fernando E. Miguez (Iowa State Univ.)


Growing population and consumer demand require that agriculture continue to increase productivity while managing environmental impacts. Efficient farm production and environmental management needs a well-informed and scientifically-based strategy. To do this, the ever- increasing volume of data from agricultural field research must be summarized, assessed, and interpreted. Meta-analysis of experimental data can be used to find overall or widespread benefits of management practices that may be difficult to fully understand with individual research projects, most of which are limited to particular climatic and soil conditions. Policy makers and producers would like to see broader application of practices that can have water or air quality benefits while maintaining or enhancing production. However, accurate scientific information is needed to know how to do this best, where it will work, and how it can be cost- effective.

Recent meta-analyses have improved the scientific certainty and understanding of the implications of tillage for nitrous oxide (N2O) emissions (van Kessel et al. 2013) as well as the impact of cover crops on N2O (Basche et al. 2014). In the spring of 2014, the 4R Research Fund supported five research teams in their efforts to conduct meta-analyses of the air and water quality impacts of on-farm 4R nutrient management. The databases compiled in this work
contain research results from a large number of field trials in North American cultivated and grassland agricultural systems. Analyses of these data provide the most up-to-date evidence of the environmental and production effects from careful management of fertilizer nutrients. The first objective of this proposed work is to summarize the 4R Research Fund-supported meta- analyses, noting how the combined data and results can advise best practice.

While performing the meta-analysis projects, researchers identified key data gaps in research published in peer-reviewed journals, and subsequent communication between teams revealed that many of the same issues were encountered. Therefore, we propose to summarize the critical data gaps found by the 4R Research Fund-supported meta-analysis teams and provide recommendations for field researchers to aid future data synthesis efforts in making the most effective use of their data following initial publication. This will ensure that field research has the best possible opportunity to advise policy, extension, and on-farm decision-making.

Summary of 4R Meta-Analyses
We will summarize the results of all five 4R Research Fund supported meta-analysis projects. We will detail the databases generated, as well as the potential for linkages between them or with other databases. (Note that the building of a master database from these projects is ongoing and will further benefit future analyses.) This summary will allow us to discuss the implications of 4R nutrient management that go beyond that possible in single research papers or even in the individual meta-analysis projects. The proposed research team includes researchers from three of the five meta-analysis projects funded by the 4R Research Fund in April 2014 (Eagle, Christianson, Cook, and Harmel) plus Fernando Miguez, a leading researcher in agricultural meta-analysis. After this team was formed, principal investigators for the remaining 4R meta-analysis projects, Dorivar Ruiz and Song Qian, were also invited to participate, with two options: 1) they can simply contribute some ideas from their experience
and be acknowledged in the resulting research, or 2) they can join as full authors working on the research paper. The choice between these two options has been left up to Drs. Ruiz and Qian.

Recommendations for Designing and Reporting Results of Agro- Environmental Research
The next step will be to outline data gaps and make recommendations for future field studies. Improved field research design and reporting can increase the value, quality, and amount of data provided and thus improve resulting meta-analyses and other future uses of the reported data. This research project will detail data quality and presentation issues that were encountered by researchers in the 4R meta-analyses projects and make recommendations for researchers, funders, and publishers of research studies.

Deliverables
Within 4–5 months from project start, results and recommendations will be available for publication as a working paper or report on the 4R website and as a Nicholas Institute publication (acknowledging the participation of other partner institutions). This will then comprise a manuscript to be submitted for peer-review publication. Prior to submission for formal peer review, the manuscript will be provided for a first round of review by the 4R TAG. Any edits resulting from this initial review would be intended as a means for the TAG to support the publication effort and would be completely voluntary on the part of the authors.

References
Basche, A.D., F.E. Miguez, T.C. Kaspar and M.J. Castellano. 2014. Do cover crops increase or decrease nitrous oxide emissions? A meta-analysis. Journal of Soil and Water Conservation 69(6):471–82.
van Kessel, C., R. Venterea, J. Six, M.A. Adviento-Borbe, B. Linquist and K.J. van Groenigen. 2013. Climate, duration, and N placement determine N2O emissions in reduced tillage systems: A meta-analysis. Global Change Biology 19(1):33–44.