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.