Tips for Successful Soybean Harvest

As harvest approaches, it’s time to talk harvest management tips to ensure every bean makes it into the bin.

Harvest Timing

Soybeans are fully mature at R8 and are typically ready to harvest 10 to 14 days after reaching maturity, depending on the environment. The crop at R8 has dropped its leaves and has a tan-brown colour, with seeds that rattle in the pods that are 95% brown. If late-season precipitation continues to fall or weeds in the canopy are an issue, a desiccate is an option. Timing for desiccation is when the least mature part of the field is less than 30% seed moisture. Use the spray to swath calculator to ensure the maximum residue level (MRL) is not affected if any pesticide product is applied to the crop late in the season. Manitoba Agriculture’s Crop Specialist for Pulses, Dennis Lange, mentions that “desiccation of soybean is not very common, typically only seen in years where weed pressure is high and could affect harvestability of the crop. I have seen growers use it to help dry down a long season variety quicker, but that’s more of a variety selection issue.”

Combine Settings

Direct combining (straight cut) soybean is the preferred method for harvest. Lange explains his tips on optimizing the combine for soybean harvest:

Concaves: Make sure you are using the correct concaves (rotary combine) for soybeans. Growers will typically use a wide-wire concave, which allows the larger seed to pass through quicker.  
Cylinder speed range: The speed should be from 500-700 RPM, which would be much slower than when harvesting wheat. 
Wind speed: Should be from 850-900 RPM to allow for good separation of the lighter material
In years with short plants, the use of an air bar with the flex header will allow for soybeans to be pushed into the header and not left laying on the knife. This will help to reduce losses at the header.

Measuring Losses

For soybean, upwards of 80% of the harvest losses occur at the header, and it only takes 4 seeds/ft2 to lose a bushel an acre. Recent work through the Prairie Agricultural Machinery Institute (PAMI) looked at variables (type of header, angle of header, air systems, and ground speed) that affect header losses. The draper header, when adjusted properly, allows for a smoother flow of plant material into the feeder house, creating less shatter potential of pods. The angle of the header is one of the most important settings to have adjusted. Knives should be positioned between the ground and at the lower tip of the bottom pod. The angle helps to distribute the cutting load across the entire header. Slower ground speeds of 3 to 4 mph have lower losses, but knowing your combine and measuring losses will be a better indicator of the appropriate speed for the field conditions. The addition of an air system was found to reduce losses by 0.5 to 1 bu/ac.

For calculating losses, check out the Manitoba Pulse and Soybean Growers’ Bean App.

Checking for losses is the first step. Stopping and assessing the number of seeds on the ground before altering settings will help determine what’s working and what’s not. Remember to count loose seeds, dropped pods and stalks that may be lodged containing pods in your counts. Always best to change one setting at a time and check again to help ensure no bean is left behind.