This proposal fulfills the priorities listed under 1., Breeding/Production/Environmental Programs. Specifically, 1.A. Best Management Practices for soybean production in Kansas.

This research aims to 1) quantify the effects of nutrition (considering N and S fertilization rates) under contrasting planting dates on yield and seed quality (protein, oil), 2) quantify effects of nutrition and planting date on overall nitrogen fixation process and budgets (sustainability), and 3) study differences in dry down until harvest time. Several soybean specialists and US states (+10 states) were involved during 2021 season, with our team from Kansas taking the lead on this initiative.

This project will provide useful information on the overall yield and seed quality impact of early- versus late- planting dates with the effect of nutrition, cultivars. This project will provide new insights on the interactive effects of nutrition and environmental factors (e.g.,. planting dates) affecting yield and even more relevant for the future soybean quality. All project outcomes will be disseminated in diverse research and extension communication outlets to help Kansas soybean producers for maximizing financial returns and preserve the land and water resources under their control.

Updated January 14, 2024:
Yields were collected and data analyzed to better understand the influence of nutrition on yields, with seed yield varied from 68 to 74 bu/a, and averaged 71 bu/an across all treatments. However, considering the 95% confidence interval, there were no significant statistical differences between treatments across all nutrition levels. For quality, the upper section of the plant contributed the most to the total protein content, with an average of 39%, which was higher compared to the middle and lower sections that both averaged 37%. However, no significant statistical differences were observed between treatments. For the effect of planting date and variation with cultivars, the study showed little effect on planting dates (early May vs early June), with an overall average for better yields with cultivars ranging from 3.4 to 4.2 maturity group, and with yields reducing when shorter (2.8) or longer (5.2) maturity groups were implemented to test the adaptability to this environment.

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A better understanding of quantities of N fixed and the soil, soybean management, and environmental factors affecting N fixation will contribute to the science leading to greater soybean yields, higher soybean quality, lower environmental impacts and sustainability, and greater returns to US farmers.