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Harvesting and Storing Soybeans

By Dr. Harold Willis

The soybean is a hardy, not-too-particular plant and can do reasonably well in a variety of soils and soil conditions, but to produce high yields of top quality soybeans, you need to get your soil into really good condition. And then, at the end of the growing season comes the most important part of soybean production — harvesting.

Harvesting Soybeans

The beans contain 45-55% moisture when mature (filled) and must dry down before being harvested. When field mature, seeds, pods and stem turn yellow. About four to nine days later, all pods on the plant have turned brown. At this point, seed moisture is about 33%. With good drying weather, the beans should be ready to harvest four to five days after this. They should be at 13-14% moisture, but with careful combining, beans of higher moisture can be successfully harvested. Shattering losses are very high below 13% moisture.

Grain elevators or seed dealers will usually measure moisture content of grain if you do not have your own meter. As a rough indication, a well dried (13% moisture) soybean will split in two easily when tapped with a hammer.

harvesting soybeans

Chemicals?

If dry-down is not likely to occur rapidly, chemical desiccant (drying) sprays can be used. Weeds are also killed at the same time. Early harvested beans usually command a higher market price, and field losses are lower with early harvest. But the desiccant kills the plant, and should not be used before seed maturity has been reached or significant yield reduction will occur. The chemicals used for drying include sodium chlorate, a powerful oxidant, and the herbicide Paraquat. Many specialists question the practice of using desiccants, and mention of the practice here does not constitute endorsement.

Reduce losses

It is very important to keep harvesting losses to a minimum in a high-value crop. Lodging and shattering losses can be partially reduced by planting resistant varieties and appropriate populations. Shattering is more likely the longer the plants stand in the field, especially with alternating wet and dry weather.

It is extremely important that the combine be adjusted and operated properly. Keep the machine in good repair. Adjust reel speed to 25% faster than ground speed. Six-bat reels feed more evenly than four- or five-bat reels.

Operate the cutterbar as close to the ground as possible. Use a pick-up reel with lodged soybeans. Generally ground speed should not exceed three miles per hour to prevent stripping of beans from the stalk; slower speeds are necessary if plant height is uneven.

Handling

Avoid excessive impact of harvested grain on hard surfaces, since dry soybeans crack easily. Run conveyors as full and as slowly as possible. Use cushion boxes to absorb impact from long drops. Warm up cold beans by aeration before transfer, since cold beans crack more easily. Soybeans above 14% moisture should be dried.

Soybean Storage

Stored grain must be kept cool and dry to prevent mold and insects from attacking. Damaged grain is also a detriment; insects seldom feed on whole soybeans. Foreign matter is often a source of mold growth. Soybeans lose and gain moisture quickly, so it is important that storage bins are well aerated to prevent moisture migration from warm areas and condensation in cool areas. Either drying fans or bin aeration fans can be used. Aerate at a rate of 0.1 cubic foot per minute per bushel of bin capacity.

In the fall, you should aerate continuously when the outside temperature is 10-15 degrees F cooler than the grain temperature until the grain reaches
40 degrees F. In the winter, aerate for 24 hours every two weeks when the outside temperature is 10 degrees F higher or lower than grain temperature. The 24 hours aeration need not be continuous.

In the spring, aerate continuously whenever the outside temperature is 10 to 15 degrees F warmer than grain temperature until grain temperature reaches 60 to 65 degrees F. All of this is made easier if you have automatic controls on your aeration system.

Saving seed

If you want to replant your own seed, save out the needed amount. Seed should be dried to about 13% moisture and kept in ventilated containers (cloth bags, cardboard boxes, or glass jars with cheesecloth covers). It should be stored in a dry, ventilated area at cool temperatures (not higher than 70 degrees F or lower than 32 degrees F). Keep away from mice and rabbits.

Seed should maintain a good germination rate for the first year (80 to 85%), but after the second year of storage, germination may drop to 65%. Test the germination rate before planting.

Source: How to Grow Super Soybeans