Soybean Planting Decision Support Tool.

Every year soybean farmers make decisions about planting date and maturity group selection. These two decisions greatly determine the yield potential and hence selection of these factors is very critical. At present, information to support decision-making is mostly in the form of publications, which are useful but hard to find quickly and farmers and agronomists still have to make their own extrapolations to adjust the information to their specific situations. We developed a Soybean Planting Decision Tool (http://agron.iastate.edu/CroppingSystemsTools/ ) to assist decision making by providing a better understanding of planting date by maturity group by location interactions on soybean yield and crop staging. The decision tool has the potential for use in extension, teaching, and research.  Within five months of its announcement (April 16, 2015; version 1.0) the tool was used by more than 3000 users. The interactive web tool was developed for Iowa through Iowa Soybean Association funds and is driven from input of management criteria into APSIM cropping system model. The tool cover Iowa’s 9 crop reporting districts, 24 planting date per location, 12 maturity options per planting date, and integrates 35 years of climatological information. The APSIM model outputs are displayed using R Shiny. For each combination, the tool provides the yield response, crop staging over the growing season, and the associated frost risk. The users can select up to three different combinations of locations or maturity or planting dates and compare the results using advanced graphic options that include boxplots, violin plots, regression lines and their confidence intervals as well as options to display the raw data for the user to see the range of variability that exists.