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Considerations for Late Soybean Harvest

University of Minnesota Extension, Stearns County News
October 11, 2017         
Source:  Dan Martens, Extension Educator
University of Minnesota Extension
Stearns, Benton & Morrison Counties

Considerations for Late Soybean Harvest
By Dan Martens, University of Minnesota Extension

FOLEY, Minn. (10/04/17) —The October 10 crop report shows soybean harvest lagging behind, showing just 22% of the Minnesota crop harvest compared to 61% last year 63% on a 5 year average. Frost on October 10, late planted beans, and wet fields contribute to a slow harvest. Some soybeans were quite green for the frost, but with better weather could still mature. Beans will be smaller if not fully developed at frost.

Here are some key points to consider with soybean harvest, based on information provided previously by Regional Extension Crops Educator Dave Nicolai. 

Field losses could be due to soybean pods shattering, lodging, and poor threshing of wet plant material within the combine. Combine header losses can be as high as 80% of the total harvest loss. It is important to remember that ground speed, combine adjustments, and the location and speed of the pickup reel have an important influence on gathering loss. These issues can also mean having more crop residue in the bin which can mean storage problems and market discounts.

How to estimate harvest loss:            
To get an estimate of your soybean harvest loss, check a measured area across the full width of the combine. Approximately 40 soybeans lost per 10 square feet represents about one bushel per acre. Make loss determinations at several locations and calculate an average. Adjust the combine for the crop conditions. Correct adjustments pay dividends.

Storage Management:
Soybeans that are wetter than 13% moisture are likely to mold under warm conditions and buyers usually apply shrink factors and drying charges for wetter beans.  If the storage temperature is kept below about 60°F, soybeans can usually be held for at least six months at 13% moisture without mold problems. For storage under warmer temperatures or for longer than six months, the recommended moisture is 11%. 

Soybeans that are harvested at 11 to 13% moisture can be placed directly into ordinary storage bins equipped with simple aeration systems (perforated ducts or pads and relatively small fans). Fall weather conditions in the upper Midwest will usually dry soybeans to 11 to 13% moisture in the field. That may not be true of all soybeans this year. Sometimes growers harvest at moistures greater than 13% to avoid the harvest losses at lower moisture levels. Soybeans can be harvested without too much damage up to about 18% moisture.

Natural-air drying:
Using unheated air to dry soybeans can work well, but it is a slow process (two to six weeks, depending on initial moisture, airflow, and weather). In southern Minnesota, use airflow of 1 cfm/bu to dry 17 to 18% moisture beans, 0.75 cfm/bu for 15 to 17% moisture beans, and 0.5 cfm/bu for 13 to 15% moisture beans. Natural air drying usually works best with average daily temperatures of 40 to 60 F.

Low-temperature drying:
Later in the fall, or in years with cool, damp weather, it might be helpful to add a small amount of supplemental heat to the air in natural-air dryers. Do not heat the air more than 3 to 5 degrees F though, or you can over-dry the beans and cause more splitting. Research has shown that exposing soybeans to relative humidity values of less than 40% can cause excessive splitting. For every 20 degrees F that air is heated, the relative humidity is cut about in half, so it doesn't take very much heat to produce relative humidity values less than 40%.

Sickle headers on combines allow farms to selectively harvest areas of field where they can.

CORN DRYING NOTE: It takes about 0.02 gallons of propane to dry one point of moisture per bushel. The propane cost per bushel per point of moisture removed can be estimated by multiplying the propane price per gallon by 0.02. For example, the cost to remove 10 points of moisture using $2.00 propane is $0.40. Divide the propane cost by the corn price to compare percent corn losses that will equal the drying cost. ($0.40/$3.00=0.13 or 13%). There are some additional operating costs and labor.

GRAIN BIN SAFETY FIRST. Shut off power to grain handling equipment before going into bins. Tell someone else what you are doing, whenever possible. Will your cell phone work inside a bin? Be careful on ladders. Consider ladder cages and roof rails.

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