Managing Soybean Harvest Timing, Moisture to Improve Yield

Managing Soybean Harvest Timing, Moisture to Improve Yield

Mature soybeans at harvest

Soybean harvest is underway in many dryland soybean fields and some early season irrigated fields. Soon it will be in full swing.

Harvesting soybeans in a timely manner and at the optimum moisture is important to getting the best yields. Even though stems may be green, soybeans may be dry and ready for harvest.

Monitoring Moisture

It's probably more common for soybeans to be harvested at 10% moisture or less than it is to harvest them at the desired 13%. Beans testing over 13% moisture are assigned a penalty that shows up on the scale ticket. Soybeans testing under 13% also are penalized, but it shows up as fewer bushels to sell rather than an item on the scale ticket.

A standard bushel of soybeans weighs 60 lb and is 13% moisture; that is 52.2 lb of dry matter and 7.8 lb of water. If you harvest soybeans at 12% moisture, you still have 52.2 lb of dry matter, but the bushel of beans weighs 59.318 lb instead of 60 lb. The lost water is 0.682 lb or a 1.137% decrease in beans delivered. If you are harvesting 60 bushel soybeans at 13% moisture and sell them for $12 a bushel, you will receive $24 an acre more than letting them dry down to 10% moisture. This loss will increase to nearly $40/acre if you harvest them at 8% moisture.

Risk is another factor to consider. The longer the beans are in the field, the greater the risk of losing them to shattering or lodging. You may want to think of the "scale ticket penalty" as an insurance premium. Giving up a little in penalties reduces the chance that severe weather or unfavorable harvest conditions may reduce your yield.

While it is impossible to harvest all your beans at exactly 13%, that should be your goal.

Soybean Harvest Tips

The following adjustments in your practices can help you get the most from your harvest:

  1. When harvesting tough or green stems, make combine adjustments and operate at slower speeds.
     
  2. Begin harvesting at 14% moisture. What appears to be wet from the road may be dry enough to harvest. Try harvesting when some of the leaves are still dry on the plant; the beans may be drier than you think. Soybeans are fully mature when 95% of the pods are at their mature tan color.
     
  3. Harvest under optimum conditions. Moisture content can increase by several points with an overnight dew or it can decrease by several points during a day with low humidity and windy conditions. Avoid harvesting when beans are driest, such as on hot afternoons, to maintain moisture and reduce shattering losses.
     
  4. Avoid harvest losses from shattering. Four to five beans on the ground per square foot can add up to one bushel per acre loss. If you are putting beans in a bin equipped for drying grain, start harvesting at 16% moisture and aerate down to 13%.
     
  5. Harvest at a slow pace and make combine adjustments to match conditions several times a day as conditions change.

While it's too late for this season, next year select your varieties and schedule your planting to spread out plant maturity and harvest.

Gary Zoubek, Extension Educator, York County
Roger Wilson, Extension Farm Management/Enterprise Budget Analyst
Chuck Burr, Extension Educator, Water/Cropping Systems