Welcome to SoyStage

SoyStage is an online tool that predicts Soybean (Glycine max (L.) Merrill) developmental stages. You can see phenology maps based on historical weather data or predict phenology for the current year.


SoyStage predicts first flower (R1), beginning seedfill (R5), and physiological maturity (R7) for maturity groups (MGs) 3 through 6 in one-half MG increments. SoyStage is based on the idea that development is a ‘photothermal’ response and that MGs differ in the coefficients that are responsive to photoperiod and temperature. The algorithms used in SoyStage were originally developed using data from a large, 3-year research project that evaluated responses of MGs 3 through 6 soybean planted at four different dates at locations that ranged from College Station, Texas to Columbia, Missouri (Salmeron and Purcell, 2016).

*Please note that SoyStage works with Emergence Date as opposed to Planting Date.

Current Year

The tab labeled ‘current year’ utilizes weather data from NASA POWER based upon postal codes as a geographical reference. The analysis on the current-year tab is based on the coefficients determined by Salmeron and Purcell (2016). SoyStage produces a table and graph showing the crop-development progress towards first flower (R1), beginning seedfill (R5), and physiological maturity (R7). The current year development is calculated from emergence until 2 days prior to the current date. The projected progress for the remainder of the current year is completed using the 95% confidence interval based upon weather data averaged over the previous 30 years.

Phenology Maps

Weather data from 1985 till 2016 for 2776 locations were used to develop the Phenology Maps on SoyStage. All total, there were 9,174,760 predictions made for each development stage. In exceptionally warm years, plant development will be faster than the average shown by the maps, and in cold years, development will be delayed. The gap between planting date and emergence date is highly influenced by weather conditions. Under optimum conditions, emergence will occur in 4 to 5 days; however, emergence may not occur until 14 days after planting or more under cold weather conditions. Harvest maturity (R8) generally occurs 7 to 10 days after physiological maturity (R7). To use SoyStage, select an anticipated or known emergence date, MG, and development stage (i.e., R1, R5, or R7). Move the cursor over the map to an area of interest. The popup displays the number of days after emergence (DAE) until the crop reaches the phenological stage chosen. The number of days is the average over 35 years of weather data; also displayed is the standard deviation of the prediction over these 35 years. Use a mouse or the zoom function in the upper left corner of the map to zoom into an area.

Freezing risk at the beginning of the season is noted on the popup screen based on temperatures less than 2°C. End of season freezing risk is not shown but later maturing cultivars emerging late, especially in northern latitudes, risk freezing.

Additional Information

SoyStage was developed by Caio dos Santos, Montserrat Salmerón, and Larry Purcell (

For more information about the research that went into SoyStage, please refer the following references. Reprints are available upon request.

  • dos Santos, C., M. Salmerόn, and L.C. Purcell. 2019. Soybean phenology prediction tool for the Midsouth. Agric. Environ. Let. 4:190036. doi:10.2134/ael2019.09.0036.

  • Salmeron, M., E.E. Gbur, F.M. Bourland, N.W. Buehring, L. Earnest, F.B. Fritschi, B. Golden, D. Hathcoat, J. Lofton, T.D. Miller, C. Neely, G. Shannon, T.K. Udeigwe, D.A. Verbree, E.D. Vories., W.J. Wiebold, and L.C. Purcell. 2014. Soybean maturity group choices for early- and late-plantings in the US Midsouth. Agron. J. 106:1893-1901.

  • Salmeron, M., E.E. Gbur, F.M. Bourland, L. Earnest, B.R. Golden, and L.C. Purcell. 2015. Soybean maturity group choices for maximizing radiation interception across planting dates in the US Midsouth. Agron. J. 107:2132-2142.

  • Salmerόn, M., Gbur, E.E., Bourland, F.M., Buehring, N.W., Earnest, L., Fritschi, F.B., Golden, B.R., Hathcoat, D., Lofton, J., Miller, T.D., Neely, C., Shannon, G., Udeigwe, T.K., Verbree, D.A., Vories, E.D., Wiebold, W.J., and L.C. Purcell. 2016. Yield response to planting date among soybean maturity groups for irrigated production in the US Midsouth. Crop Sci. 56:747-759.

  • Weeks, W., M. Popp, M. Salmerόn, L.C. Purcell, E.E. Gbur, F.M. Bourland, N.W. Buehring, L. Earnest, F.B. Fritschi, B.R. Golden, D. Hathcoat, J. Lofton, A.T. McClure, T.D. Miller, C. Neely, G. Shannon, T.K. Udeigwe, D.A. Verbree, E.D. Vories, W.J. Wiebold, and B.L. Dixon. 2016. Diversifying soybean production risk using maturity group and planting date choices. Agron. J. 108:1917–1929.

  • Salmerόn, M., and L.C. Purcell. 2016. Simplifying the prediction of phenology with the DSSAT-CROPGRO-Soybean model based on relative maturity group and determinacy. Agr. Syst. 148:178-187.

  • Salmerόn, M., L.C. Purcell, E.D. Vories, and G. Shannon. 2017. Simulation of soybean genotype-by-environment interactions for yield under irrigation in the Midsouth with DSSAT-CROPGRO. Agr. Syst. 150:120-129.