Soybeans will be planted at three research and education centers (RECs) in Maryland: Western Maryland REC (Keedysville, MD), Clarksville REC (Clarksville, MD), and Wye REC (Queenstown, MD) at three different dates. Dates will be approximately mid-April, early May, and late May, spaced out approximately two weeks. The same variety, a commonly available mid group IV, will be planted on all three dates. We will establish six replications at each location, for a total of 54 experimental units. Following emergence, plots will be assessed for early season seedling diseases and will be scouted for disease throughout the season. Tissue and soil samples from each plot will be sampled at R1-R2 to observe any differences in nutrient uptake. Yield will be collected at the end of the growing season using a harvested with an Almaco R1 research combine (Almaco Co., Nevada, IA). Tissue and soil samples will be analyzed by the University of Delaware Soil Testing Lab. Tissue nutrient content will be correlated to yield, soil nutrient levels, and soil type. Trends in yield related to planting date, nutrient content, and soil nutrient status will be compared.

1. Plant full season soybeans at three different dates.
2. Evaluate soybeans for nutrient deficiencies, disorders, or pest pressure.
3. Compare tissue and soil samples to yield after harvest.

Update:
All planting dates across the three locations were planted in a timely manner. Co-PI Andrew Kness has visited each location, taking note of any observed pest or disease issues. As each location has entered R1, soil and tissue samples have been collected. Some soil samples were not collected due to dry soil conditions making sample collection not possible. Samples have been submitted to University of Delaware Soil Testing Laboratory and we anticipate an uneventful remainder of the growing season.

Update:
We had a successful 2021 growing season where we were able to successfully complete the project
generally as proposed at the three locations: Wye, Clarksville, and Keedysville Research and Education
Centers (RECs). We started planting at the Clarksville location first and did not yet have the seed for the
MG 3 soybean, so we established the trial with early MG 4, late MG 4, and MG 5 soybean varieties only
at this location. Both the Wye and Keedysville locations had all four varieties with three different planting
dates (total of 12 treatments). Tissue and soil samples were collected as best as possible near R1-R2
growth stage for the late MG 4 variety only (paired project with UDel, PI Dr. Jarrod Miller), except at
locations where rainfall limited our ability to properly collect a soil sample (i.e. soil too dry for
collection). Table 1 shows which soil and tissue samples were collected in the 2021 growing season. All
plots were evaluated for disease throughout the season and yield was collected from each plot as proposed
for 2021.

View uploaded report

Update:
We successfully wrapped up the 2021 growing season collecting tissue and soil samples as best as possible. With additional funding in 2022, we hope to draw appropriate conclusions based on multiple site years of data on the value of early planting on increasing yields and nutrient status of full season soybeans.

View uploaded report

After multiple years of this study, we plan to provide soybean farmers with updated recommendations on planting date for soybeans, namely across different maturity groups. As production systems shift with the increasingly unpredictable spring weather, farmers are looking for guidance on how they may change planting date to increase resiliency and productivity of their operations – by maintaining or increasing soybean yields.

The transition from vegetative to reproductive growth in indeterminate soybeans depends on the detection of night length, or number of hours without sunlight as the season continues. As soybeans are planted later into the growing season, they do not have as much time to develop biomass. They also miss the opportunity for longer days and intercepting additional sunlight, to drive photosynthesis towards production of pods – which could decrease yield. The general hypothesis is a longer growing season, and therefore greater photosynthesis, could increase soybean yields.