Several factors contribute towards the yield of Soybean [Glycine max (L.) Merr.] including genetic traits of the cultivar, environmental factors, and management practices. Continuously changing weather patterns across the United States in general and especially in the Midwest have intrigued the scientific community to re-examine how agronomic practices play with the environmental conditions to impact yield. Planting soybean after finishing corn planting has been a general practice in Kansas. However, several research findings in neighboring Midwestern states have indicated that producers can profit from planting soybeans earlier. Though some studies have shown that the scale of the response to early planting can vary between years (Pedersen and Lauer, 2003), location (Lueschen et al., 1992), and cultivars (Grau et al., 1994), more recent studies show a general trend of higher yields associated with earlier planting dates (Nleya et al., 2020). Results of 24 tests done on dryland soybean in Iowa found that yields were higher 79% of the time when soybeans were planted in late-April or early May as compared to 3rd week of May or later (Source: https://www.agprofessional.com/). In northeast and north central Kansas planting dates are also dependent on factors like soil moisture and soil temperature which will be studied as a follow up after obtaining preliminary results from this study. Given the research findings form other neighboring states and understanding that dryland soybean yields are greatly influenced by weather patterns, it becomes imperative to explore earlier planting dates for better yield and profitability of Soybeans in different parts of Kansas.

Identify best early planting dates for soybean in North East and North Central parts of Kansas and study the impact on soybean yields under varying environmental conditions

All project outcomes will be disseminated in diverse research and extension communication outlets to better educate Kansas soybean producers and agri-business professionals.

Update:
To capture the variability of environmental factors, we planted soybeans at three planting dates spread nearly three weeks apart at two research sites. Two target populations of 100,000 and 150,000 seeds per acre and two varieties (late 2 and late 3 maturity) were chosen. All cultivars planted were glyphosate [N-(phosphonomethyl) glycine] resistant and the seeds were inoculated. Varieties with resistance to soybean cyst nematode and sudden death syndrome (SDS) were used. With a long-term goal of modeling the impact of different planting dates and environmental factors on soybean production, we recorded early season measurements and biomass samples and will record grain yield components – pod number, grain number per pod, and grain weight and yield at harvest - number of seeds produced/m2 and individual seed mass.

Update:
To capture the variability of environmental factors, we planted soybeans at three planting dates spread nearly three weeks apart at two research sites. Two target populations of 100,000 and 150,000 seeds per acre and two varieties (late 2 and late 3 maturity) were chosen. All cultivars planted were glyphosate [N-(phosphonomethyl) glycine] resistant and the seeds were inoculated. Varieties with resistance to soybean cyst nematode and sudden death syndrome (SDS) were used. With a long-term goal of modeling the impact of different planting dates and environmental factors on soybean production, we recorded early season measurements and biomass samples and will record grain yield components – pod number, grain number per pod, and grain weight and yield at harvest - number of seeds produced/m2 and individual seed mass.

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Since this was year 1 of this multi-year trial there are no conclusive results on impact of early planting on end of season yield yet. We observed a lot of variability between sites, planting dates and populations. For the Scandia site, mid April planting date had highest grain yield components and the late 2 variety @150k produced the best end of season yield results. Distribution of yield with respect to planting date and plant population results are added in the file attached. We could observe impact of soil type as well as regional variation between the sites.

This research can provide research based critical knowledge to farmers in the region to modify their planting management practices for closing yield gaps. We believe that this research can form a basis of defining best management practices for maximizing financial returns while making sustainable use of Kansas’ natural resources.