Harvesting Factors that Contribute to Maximizing Soybean Yield

Soybean harvest can be delayed for many reasons, from uncooperative weather to equipment downtime. Other times, a lack of adequate harvest planning and scheduling may be the hold up. There are many physical ways yield loss occurs when harvest is delayed, but field loss and moisture levels are generally the reason. Another concern is that excessively wet weather results in moldy soybeans, elevator dockage and field losses. Compared to corn, soybeans are more delicate once maturity is reached. With alternating wet and dry weather patterns, soybeans are even more fragile.

To maximize soybean yield at harvest, consider the following:

• Reduce soybean field loss
• Manage soybean moisture levels
• Minimize soybean pod shatter

Reduce soybean field loss

Field loss ranging from 5%-12% of total yield potential can occur before and during harvest.¹ Over half of that field loss is typically attributed to header or threshing losses, related to combine efficiency. Delaying harvest until soybeans are below 11% moisture can increase the likelihood of pod shattering. Repeated drying and wetting cycles can further increase yield losses while waiting to harvest. Harvesting early and properly adjusting your combine are two of the best ways to minimize these types of losses. Harvesting at moisture content from 13%-13.5% is optimal for minimizing mechanical damage. If bins are equipped to air dry soybeans, harvest can start as early as 16%-18% moisture and easily aerate to 13% moisture to help minimize field loss.

Manage soybean moisture levels

A standard bushel of soybeans weighs 60 lbs. at a standard 13% moisture. Soybeans delivered at moisture levels greater than 13% are usually discounted by the buyer using a calculated discount rate. Weight loss from soybeans with moisture levels less than 13% is not taken into consideration for calculating total bushels sold. The moisture loss results in reduced harvest weights and fewer bushels sold.

The soybean moisture chart below illustrates the percent of total yield loss for every moisture point below 13%. As a result, soybeans discounted for being wetter than 13% can sometimes be more profitable than delivering drier beans. The following example calculates soybeans delivered at 14% moisture with a 3% price discount, compared to the same soybeans delivered at 8% moisture. The calculation below doesn’t account for the incremental field loss that likely occurred from a delayed harvest.

Example:

• 14% moisture = 3% dock
       3% price dock of original price ($8.50/bu) = $8.25 x 80 bu/A = $660 gross per acre
• 8% moisture = 0% dock
       5.4% yield reduction x 80 bu/A = 4.3 bu less – 80 bu/A = 75.7 bu x $8.50/bu = $643 gross
       per acre

Impact of harvesting soybeans at moisture levels less than 13%²

If fields receive too much moisture when harvesting late-season soybeans, use the following strategies to help minimize soybean yield loss from moisture:

• Wait until soil can support machinery: Delay combining until the ground is dry enough that soil compaction won’t damage your field and continue reducing yields years later. 
• Monitor moisture levels: Although soybeans can be harvested at a moisture of 20% or less, add 1.5% to the calculated rate. Moisture monitors often underestimate high moisture beans.
• Combine carefully: Wet soybeans are tougher to cut, so make sure your header is sharp and reduce combine speed to harvest more uniformly.
• Keep thorough harvest records: If getting elevator dockage for moldy soybeans is a concern, check with your seed supplier about potential damage discounts. 

Minimize soybean pod shatter

Although Golden Harvest^® soybeans are bred to withstand greater environmental stressors than ever before, there is still a chance of pod shatter under extremely wet weather conditions. When this happens, soybeans may drop and/or become exposed to the environment. Pathogen exposure can lead to mold and disease. To minimize elevator dockage, dry and market moldy soybeans as soon as possible. Avoid high temperatures when drying soybeans, since too much heat can crack the seed and hull. To reduce the chance of splitting seed coats from air-drying, relative humidity should be greater than 40%. 

Tips to increase soybean yields

Keep these 6 tips in mind to maximize soybean yield potential at harvest:

1. Inspect your machinery: Make sure your belts, chains, rasp bars, cylinders and other parts on your harvesting equipment are clean and have minimal wear before you are ready to use them. Inspect the cutter bar thoroughly, as the majority of machine losses occur at the head, and be sure all knives are sharp and ready to work as effectively as possible. Soybean harvest losses can be managed by timely harvest and proper combine adjustments, which may be needed multiple times throughout the day, depending on changing moisture and weather.
2. Consider timing: When it comes to harvest, timing is everything. Corn is often harvestable before soybeans, so be sure to analyze each of your fields before beginning to gather your pods. This will help you capitalize on your time and is crucial to yield success.
3. Scout your fields: Weeds can put a serious dent in your harvest plans. Viny weeds may pause the harvest process, so be sure to spray or wait until they drydown to begin harvesting. Green stem, though often unpredictable, is another surefire way to interrupt harvest. If your crop is experiencing green stem as a result of having few pods, wait for a frost to freeze out the green.
4. Monitor moisture: Moisture levels vary from field to field based on weather and environment conditions. Repeated drying and rewetting cycles can stunt your yield significantly, so vigilantly monitor and plan to harvest your soybeans around 15% moisture. Soybeans that dried down and became wet again during rainy, cool and cloudy weather will more easily split and shatter, so be extra careful harvesting in such situations. Below 11% moisture may cause your crop to shatter and higher than 15% moisture is too wet to harvest. Check each field closely as soybeans with green stems or a few remaining leaves may be drier than perceived. Avoid harvesting when beans are at their driest of the day, such as on hot afternoons, to reduce pod shatter; 4-5 seeds per square foot found on the ground is the equivalent of 1 bushel per acre yield loss. To get the best return on investment, some farmers may want to consider blending loads of high and low moisture soybeans before delivering them to the elevator to create an average of 13% moisture level. 
5. Plan ahead for storing: If you plan on storing your soybeans for future delivery, be sure to scout for risks that may ruin your harvest. Vines, green pods and weed seed can spoil your entire bin if left unchecked.
6. Be safe: Harvest can be exhausting and dangerous. Be sure to get enough rest, stay hydrated and follow all machinery operating warnings to ensure a successful and safe harvest.

Visit with your local Golden Harvest Seed Advisor for questions and more agronomic insights.