Soybean development in 2024 running 10 days ahead of the five-year average 

By Shaun N. Casteel, Purdue Extension Soybean Specialist 

Soybean development in 2024 has been about 10 days ahead the five-year average from flowering to pod development to leaf drop (USDA-NASS, 2024). Fast stand establishment and high accumulation of heat units (GDDs) during May and June certainly set the pace. Now, in many areas, harvest is fully in gear based on the combinations of early maturities, early plantings and late season heat and dryness. 

Timely planting is foundational for maximizing soybean production. Growing up in the Midwest, the mindset was to plant corn first followed by soybean. As long as it was planted by Memorial Day you were “fine.” That sentiment has changed based agronomic research, Extension recommendations, and farmers’ experience. 

Indiana soybean planting shifted dramatically in 2018 to within four days of corn planting where it had averaged 14 days behind corn the previous 10 years. In fact, Indiana farmers continue to place high priority on soybean planting to the point that many plant soybeans before corn or at least at the same time as corn. 

Indiana soybean planting now occurs within just 1.5 days of corn planting in 2022 and 2023 (USDA-NASS, 2024). The general sweet spot for soybean planting is late April to early May depending on the field conditions. We can certainly plant earlier in April depending on the year. 

These timely plantings have led Indiana farmers to break yield records in 2018, 2020, 2021 and 2023. The crop forecast for 2024 is set to break another record. Though, late-season drought conditions have likely taken some of the sprinkles and maybe the icing off the cake for soybean yields. 

As my dad would say, the crop is not made until it is harvested and in the bin. We need to be ready for the early crop and timely for optimal harvest and return. Soybean crops don’t have the luxury of high moisture harvest like corn, so we have to be timely on the harvest regardless of stem greenness or pod color. 

We sell soybeans on 60-pound nuggets and not truly bushels as a volume. These 60-pound units that we affectionately call bushels are taken at 13 percent moisture, but they are equally taken at 10 percent moisture. Unfortunately, we do not get that 3 percent water weight given back and adjusted accordingly. 

This 3 percent difference in water weight would reduce a 60-bushel crop to 58 bushels per acre and a 75-bushels crop to 72.5 bushels per acre. These “yield losses” are based on water weight alone (Table 1), and does not account for combine losses such as shattering due to dry seeds. 

One should consider yield map corrections based on harvest moisture, so fields are accurately represented agronomically for any management decisions and trends as well as nutrient removal corrections. Please note that adjusting the yield maps has merit for your agronomics, but it will not change the economics if harvest was below 13 percent. 

Another point to consider in setting the combine for harvest is your tolerance for soybean seed loss at the header and the spreader. Depending on seed size, we can lose one bushel for every 4-5 seeds per square foot on the ground. Poorly set sieves and high fans can lose many seeds out the rear. Header loss can account for significant loss, especially as the fields dry out or go through several wet-dry cycles. Target seed loss should be less than 3 percent. 

Field variability will certainly play into proper harvest settings and timings. Best of luck as you bring in the 2024 crop timely, efficiently, and safely.