Month: September 2021

Del Voight – Penn State Extension Crop Management Team

Some variability in dry down of soybeans. Notice wet spots that have delayed senescence. This field will be getting close to harvest moistures within the next couple of weeks.

Over the last several years of working with what I consider the top soybean producers in Lebanon County I have learned the importance of timely harvest of soybeans. This week  I noticed late group 2  beans were approaching harvest moisture.  It has been my experience that once 95% of the pods turn brown about a week later its time to combine. Some recent work at Iowa State showed a 3.2% loss of moisture per day  more than 5 times that of corn. So dry down is quick.  The data also suggested about 12 days after pod maturation 13% moisture was noted over the study period. For more information visit https://crops.extension.iastate.edu/cropnews/2017/09/how-fast-do-soybeans-dry-down-field

Once moistures dip below 13%  a grower grower is essentially giving the mill soybean dry matter since they will correct the moisture to 13%.    I still remember John Yocum referring to the fact that after it the plants first reach harvestable moistures dry matter losses occur simply by the alternating day night and heavy dew.  Here is a picture of our crop teams’ soybean planting date study.  Same variety, same seeding rate, same pest management program, the only variable was the date of planting in these plots from March 28^th to May 28.  It is important to consider the variety since some varieties will have slight differences in the pod integrity and not tend to split as the heavy dew at night can speed up this process. There are also impacts of erect varieties that might tend to dry quickly and delays in harvest may impact those versus varieties that that  tend to lay over and nestle protecting large fluctuations in dry down. This picture was taken from our Landisville Research Station where I had planted the same variety on 5 different planting dates when the early planting was ready to combine the soybeans on the left (planted two weeks earlier than the beans on the right) could be harvested two weeks before later plantings.  If I were to wait as little as two weeks to harvest the plots until the rest of the planting dates matured I would lose a significant amount of soybeans from shatter losses.

Numerous tests of soybean combine losses show that up to 12 percent of the soybean crop is lost during harvest. Harvesting losses cannot be reduced to zero, but they can be reduced to about 5 percent. Combines can be operated to reduce losses without affecting the harvesting rate. This guide describes the major sources of loss. Consider shatter losses of 2 percent acceptable. Average losses are 5 percent or more.

If you assess the discount for bringing soybeans in a little wetter than normal there will be realized return in both less shatter loss and more income. In the following table you will note the relative cost per bushel of soybeans to be around 30 cents. This is a cost that is easily overcome by the reduced harvest loss in the field at current market prices.  It appears that soybean dryer than 13% return about the same to management but this does not take into account the penalty of shatter loss in the field. You can check your own mills by changing the discounts and market price here. Simply download from this location. soybean discount table

Tips for keeping combine losses low

There are combine heads that force air back into the platform to assist in reducing harvest as well as other types of heads. However there are some simple rules to follow.  I found the following excerpts from a Missouri article useful during harvest to capture the losses that may occur during harvest.   (Missouri Department of Agricultural Engineering)

Your best guide for correct combine adjustment is your operator’s manual.
Remember that more than 80 percent of the machine loss usually occurs at the gathering unit. The height of the cutter bar directly impacts what beans get into the bin.  If I were to harvest pods by hand versus as little as a 3.5 inch height of cut that would equate to a 5% loss just from the cutter bar height go to 5 inch height of cut and that jumps to 10% loss.  The following suggestions will help keep these losses to a minimum.

• Make sure that knife sections, guards, wear plates and hold-down clips are in good condition and properly adjusted.
• Use a ground speed of 2.8 to 3.0 miles per hour. To determine ground speed, count the number of 3-foot steps taken in 20 seconds while walking beside the combine. Divide this number by 10 to get the ground speed in miles per hour.
• Use a reel speed about 25 percent faster than ground speed. For 42-inch-diameter reels, use a reel speed of 11 revolutions per minute for each 1-mile-per-hour ground speed.
• Reel axle should be 6 to 12 inches ahead of the cutter bar. Reel bats should leave beans just as they are cut. Reel depth should be just enough to control the beans.
• A six-bat reel will give more uniform feeding than a four-bat reel.
• Complete the harvest as quickly as possible after beans reach 15 percent moisture content.
• A pick-up type reel with pick-up guards on the cutter bar is recommended when beans are lodged and tangled