We had two project meetings (Nov 2015-Minneapolis & Nov 2016-Phoenix) during the ASA/CSSA/SSSA annual meetings. All project collaborators (total: 10) attended the meeting. Dr Peter Kyveryga (Iowa Soybean Association) was also present. We discussed project objectives, outputs and logistics, and we agreed on a model for data collection and assimilation. The 10 states were grouped into two categories (east: OH, IL, IN, MI, WI; west: IA, ND, MN, KS, NE), and project PIs Grassini (NE) and Conley (WI) supervised data collection in one category each. NE and WI are responsible to quality control the data and input them into a digital database. We agreed that the database can be shared with project collaborators, but sharing it with third parties will require explicit permission by project PIs and NCSRP. During the meetings, we agreed on targeted number of surveyed fields per year and per state, which was decided based upon the current soybean acreage in each state. Shortly after the first meeting (Nov 2015), the two Post-Doctoral Research Associates started working on the project under the supervision of PIs Grassini and Conley. The NE-WI core team has had bi-weekly Skype calls to discuss and monitor project progress.

With substantial input from all project collaborators, we designed the survey form to collect soybean producer field data (see FIGURE 1, which shows a survey that was completed by an IA producer in Jan 2017). The survey design reflects a compromise between two KEY objectives: (i) to collect the most relevant agronomic information, and (iii) to keep the survey short and concise to make sure that producers will be willing to fill it out. Requested information included yield, field location, and detailed information on crop/field/input management, such as planting date, soybean variety, tillage method, etc. The survey form was distributed among soybean producers in each state, through Extension Educators, extension events and media, crop consultants, state soybean growers’ boards (including ISA), Natural Resources Districts, etc. State collaborators were requested to collect data from fields planted with soybean in 2014 and 2015 (year 1 of the project), and 2016 (year 2 of the project) before April 1 and to send the forms to the NE-WI core team before April 30. Just to give an idea of the magnitude of the task, more than 10,000 survey forms were sent to soybean producers only in NE. Our project was publicized through different venues, including extension events and media, newsletters, Ag media press releases, etc. (e.g., http://cropwatch.unl.edu/2016-soybean-survey; http://brownfieldagnews.com/2016/03/24/finding-whats-limiting-soybean-yields/; http://www.coolbean.info/pdf/home/UW_16_Principles_for_data_collection.pdf). Total number of surveyed fields (by April 20, 2017) is 1,761 (year 2014), 2,058 (year 2015), and 1,965 (year 2016), resulting in a total number of 5,738 surveyed fields (>500,000 acres). Number of surveyed fields per state are: OH (447), IL (236), IN (107), MI (538), WI (523), IA (1,187), ND (849), MN (109), KS (208), and NE (1,580). Number of surveyed fields for IN and MN are substantially below target. We will coordinate with the corresponding state collaborators to continue data collection during summer until reaching a number of fields that is closer to target. Up to date (April 20, 2017), we have inputted data from 65% of the surveyed fields planted with soybean in 2016. A full report of the data is available at: http://soybeanresearchinfo.com/pdf_docs/NCSRP_Benchmarking_Project_Summary_July2016.pdf

The NE-WI core team spent substantial amount of time determining the best way to input the producer-reported data, quality control measures, mapping of field boundaries, and identify best sources of weather, soil, and terrain data to be used to retrieve associated information for each individual field-year case. We also spent substantial efforts at identifying best sources of weather, soil, and terrain data, to determine which specific variables to retrieve, and how to do it efficiently. We have decided to use the USDA-NRCS gSSURGO soil database and Digital Elevation Model Raster map to retrieve soil and terrain attributes, respectively, and use DAYMET as a sources of weather data. We had also developed efficiency methods to extract and quality control the survey data and auxiliary soil and weather info. We published an article in a peer-review international journal about selection and quality control of US weather data sources (Mourtzinis et al., 2017). Preliminary results from the project were also presented at several scientific meetings, including ASA/CSSA/SSSA (Nov 2016), NCSRP board meeting (Dec 2016), Soybean Breeders Workshop (Feb 2017) and many extension venues. Likewise, results have been disseminated through several extension online publications (e.g., (http://ipcm.wisc.edu/blog/2016/07/benchmarking-soybean-production-systems-in-the-north-central-usa/; https://www.ag.ndsu.edu/cpr/plant-science/preliminary-results-soybean-survey-2015-05-05-16).

Planned activities for the remaining portion of Year 2 of the project (May 1, 2017 to Sept 30, 2018) are to continue collecting and inputting field information collected during Year 2, retrieve weather and soil data, create statewide reports for project collaborators, run preliminary analysis of the data collected so far, and have a NE-WI core team meeting in Aug 2017. There are also two more publications in a final stage of preparation, which will be submitted for publication in peer-review international journals before end of year 2 of the project (Rattalino et al. & Mourtzinis et al.). All project partners, including our contacts at ISA, will be included as co-authors in these two articles. Likewise, we plan to write numerous extension articles to disseminate results from the project during the 2017 summer and we will give two invited presentations at the International Soybean Research Conference in Sept 2017 at Savannah, GA.

Updated December 29, 2018:
State collaborators were requested to collect data from fields planted with soybean in 2014, 2015, 2016, and 2017. The survey form was distributed among soybean producers in each state, through Extension Educators, Extension events and media, crop consultants, state soybean growers’ boards, etc. Completed forms were sent to the NE-WI core team before May 1, each year. After quality control, the total number of surveyed soybean fields collected during the entire project was 8015 soybean fields, representing nearly 500,000 acres. The final number of surveyed fields per state collected during the three years of the project were: OH (747), IL (527), IN (234), MI (956), WI (650), IA (1327), ND (1002), MN (271), KS (318), and NE (1938). The total number of surveyed fields was very close (or even above) our total target number of surveys per state and per year. Exceptions were IN and KS, which were substantially below target. As far as we know, the data collected through this project represent the largest public on-farm database with complete yield, agronomic practices and soil-weather data that exists in the world!

The NE-WI core team spent substantial amount of time inputting the producer-reported data and applying quality control measures using a very detailed, transparent, and rigorous protocol to detect erroneous or suspicious data entries. Follow up with some soybean producers was needed to verify some of their survey entries. Surveyed fields containing missing yield data or without field location were automatically eliminated from the database. Note total number of surveyed fields indicated above (8015 fields) corresponded to the final database AFTER inputting and quality control. Likewise, we mapped the field boundaries using Google Earth® and identified best sources of weather, soil, and terrain data to retrieve associated climate and soil information for each individual field in each year. Weather, soil, and terrain data were retrieved for each field from the best publicly available sources: DAYMET weather database (https://daymet.ornl.gov/), USDA-NRCS gSSURGO soil database (http://www.nrcs.usda.gov/wps/portal/nrcs/detail/soils/survey/geo/?cid=nrcs142p2_053628) and terrain attributes (http://www.saga-gis.org/saga_tool_doc/2.1.3/ta_hydrology_15.html). The data were archived in excel format, with columns indicating the different parameters (yield, planting date, etc.), and rows corresponding to specific field x year cases. This file is available to NCSRP upon request. We will keep data strictly confidential and never disclose producer contact information.

To date the team has published a total of five scientific articles, in four different international, peer-review journals:
Azzari G, Grassini P, Rattalino Edreira JI, Conley S, Mourtzinis S, Lobell DB (2019) Satellite mapping of tillage practices in the U.S. Corn Belt since 2007. Remote Sensing of Environment 221, 417-429.
Andrade JF, Rattalino Edreira JI, Mourtzinis S, Conley SP, Ciampitti IA, Dunphy JE, Gaska JM, Glewen K, Holshouser DL, Kandel HJ, Kyveryga P, Lee CD, Licht MA, Lindsey LE, McClure MA, Naeve S, Nafziger ED, Orlowsky JM, Rosso J, Staton MJ, Thompson L, Specht JE, Grassini P (2019) Assessing the influence of row spacing on soybean yield using experimental and producer survey data. Field Crops Research 230, 98-106.
Mourtzinis S, Rattalino Edreira JI, Grassini P, Roth A, Ciampitti IA, Licht MA, Kandel H, Kyveryga PM , Lindsey LE , Mueller DS, Naeve SL, Nafziger E, Specht JE, Stanley J, Staton MJ, Conley SP (2018) Sifting and winnowing: Analysis of farmer field data for soybean in the US North-Central region. Field Crops Res. 221, 130-141.
Rattalino Edreira JI, Mourtzinis S, Conley SP, Roth A, Ciampitti IA, Licht MA , Kandel H, Kyveryga PM , Lindsey LE , Mueller DS, Naeve SL, Nafziger E, Specht JE, Stanley J, Staton MJ, Grassini P (2017) Assessing causes of yield gaps in agricultural areas with diversity in climate and soils. Agric. For. Meteoro. 247, 170-180.
Mourtzinis S, Rattalino Edreira JI, Conley SP, Grassini P (2017) From grid to field: assessing quality of gridded weather data for agricultural applications. European J. of Agronomy 82, 163-172.
Another paper has been submitted to Agricultural & Forest Meteorology (Rattalino Edreira et al, submitted) and another article is under final preparation (Mourtzinis et al.). Our team also gave more 20 oral and poster presentations at national and international scientific conferences based on results from the project.

Drs. Grassini and Conley has integrated results generated from this initial analysis into all of their Extension programming this past winter. This includes 60 Extension presentations to ca. 5,000 farmers, crop consultants and industry reps per year. We prepared a detailed summary report based on the surveyed data, which was shared with NCSRP members, project collaborators, state commodity boards, and other colleagues involved on data collection. We also published three Extension articles based on project outputs:
Andrade JF, Rattalino Edreira JI, Mourtzinis S, Conley SP, Ciampitti IA, Dunphy JE, Gaska JM, Glewen K, Holshouser DL, Kandel HJ, Kyveryga P, Lee CD, Licht MA, Lindsey LE, McClure MA, Naeve S, Nafziger ED, Orlowsky JM, Rosso J, Staton MJ, Thompson L, Specht JE, Grassini P (2019) Assessing the influence of row spacing on soybean yield using experimental and producer survey data. Available URL: https://coolbean.info/wp-content/uploads/sites/3/2018/11/2018_Soybean_row_spacing_Final.pdf
Mourtzinis S, Rattalino Edreira JI, Grassini P, Roth A, Ciampitti IA, Licht MA , Kandel H, Kyveryga PM , Lindsey LE , Mueller DS, Naeve SL, Nafziger E, Specht JE, Stanley J, Staton MJ, Conley SP (2018) Sifting and winnowing: analysis of farmer field data for soybean in the US North-Central region. Available URL: http://www.ncsrp.com/pdf_doc/Progress%20Reports%202018/Sifting%20and%20winnowing%20Extension_Article_2018.pdf
Rattalino Edreira JI, Mourtzinis S, Conley SP, Roth A, Ciampitti IA, Licht MA , Kandel H, Kyveryga PM , Lindsey LE , Mueller DS, Naeve SL, Nafziger E, Specht JE, Stanley J, Staton MJ, Grassini P (2017) Key Management Practices That Explain Soybean Yield Gaps Across the North Central US. Available URL: http://www.coolbean.info/library/documents/2017_SoybeanYield_Final.pdf
Our preliminary findings were also publicized through the SRII website, extension websites and events, newsletters, etc. (e.g., http://illinifarmreport.blogspot.com/2016/02/benchmarking-soybean-production-systems.html; http://www.soybeanresearchinfo.com/index.php?id=36&p=&search=; http://ipcm.wisc.edu/blog/2016/10/calculating-the-soybean-yield-gap-for-wi-soybean-farmers-2/; https://stepupsoy.osu.edu/soybean-production/soybean-yield-gap-research; http://msue.anr.msu.edu/news/survey_to_help_michigan_soybean_producers_identify_and_overcome_yield_gaps; http://ilsoyadvisor.com/agronomy/2017/october/understanding-yield-gaps-to-improve-yield-and-profitability/; Yield Gap Report Back).

A final report per state will be prepared in early 2019 and distributed among project collaborators as well as soybean state, regional, and national boards. We also had a team meeting every year of the project at the annual ASA/CSSA/SSSA meeting to discuss project progress and opportunities to leverage on the output from this research.

Major take-aways from the project are:
1. Yield gap between yield potential and on-farm producer average yield is 20-30% depending upon region
2. Our approach combining farmer survey data and a spatial framework allowed us to identify yield limiting factors across millions of acres planted with soybean in the US North Central Region
3. Planting date, tillage, foliar fungicide and/or insecticide, and maturity group (and their interactions) where the most important factors explaining the yield gaps
4. A priority for the future should be to validate the results from this study through on-farm trials. This is what we are planning to accomplish in the new NCSRP-funded project.
5. Maintaining a "minimum' long-term survey data collection plan should be another priority. Such a database would allow NCSRP to capture emerging trends, monitor closure of yield gaps, defend US soybean producer practices, and quantify impact of investments on ag research and Extension.