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), and 2) 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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Updated August 4, 2024:
The project has been harvested and all data processed. The maturity groups (MGs) showed a significant impact on yield for both planting dates. The highest yields were achieved with maturity groups 3-4 regardless of the planting date, averaging 84, 81, and 90 bu ac-1 for early, and 80, 77, and 80 bu.ac-1 for the late planting dates. The shortest and the longest MGs (2.8 and 5.2) presented yield penalizations, averaging 75 and 70 for early, and 61 and 60 bu.ac-1 for late planting dates.

View uploaded report

Our results showed that delaying the planting date increase moisture lost per growth degrees days (GDD). Furthermore, late planting date requires less GDD than early planting date resulting in faster dry-down, affecting the dry down process. Furthermore, our study showed significant impact of MG for both planting date on seed yield. The highest yields were achieved by MGs 3.4, 3.8 and 4.2, regardless of the planting date, averaging 84, 81 and 90 bu ac-1 for early, and 80, 77 and 80 bu ac-1 for late planting dates. The shortest and the longest MGs (2.8 and 5.2) presented yield penalizations.
Further details were included in the attached report, presenting all the information and a complete summary for this project.

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.