It seems like we often over look soybeans. We sometimes neglect our management of them, partially because we may not feel that we make as much money on them and that they just aren’t as profitable as corn. And while this is true to some extent, it is important to maximize our profits as much as we can for soybeans. With that in mind, I thought we could spend some time today talking about soybean harvest: when to harvest, tips for harvesting, and ways to be more profitable.
Soybean Maturity
Soybeans are at physiological maturity (R8) when 95% of the pods are brown or tan, which is their mature color. Keep an eye on fields as colors begin to change, as they can advance rapidly. It can also be hard to assess the percent mature pods, especially if stems of plants are still green. Be sure to look past the green stems and leaves to get an accurate count.
Harvesting Green
Often times, a field will be ready to harvest before stems have turned completely brown. This sometimes takes a hard freeze before the stems will turn. When this is the case, it is still important to harvest on time. Harvest based on pod color and moisture and not on stem color and lower leaf retention. If harvesting green, make some combine adjustments to better process the plants. First, make sure feeder house chains and rasp bars are not rounded to get a better grip on the stems. Secondly, get more aggressive with threshing by increasing cylinder and rotor speeds. Keep the concave open fairly wide in order to pass the green material through. Next, increase the fan speed to push green material across the sieves. Finally, an air reel will help feed material into the head more uniformly.
Harvest and Shatter Loss
The two major sources of seed loss come during the harvest process and from shatter loss. 85-90% of machine losses occur at the head, and of that percentage, the majority occur at the cutter bar. Keep your cutter bar in good shape and check it regularly. Additionally, every inch cut above necessary equals about a 1 bushel per acre loss. Seed loss out the back is also considered harvest loss. Three to four seeds per square foot equals about one bushel per acre loss. Make frequent adjustments to combine settings to manage these losses.
Shatter loss can be a significant source of yield loss in a field. Beans gain and loose moisture fairly rapidly, much more rapidly than corn. As this shrink/swell process happens over and over, the pods begin to get fragile. Once beans first get below 13%, the risk of shattering increases. It is at this point that the shrinking of the pod as during dry down may be to the extent that the pod will not be able to accommodate the swell of beans as moisture increases back above 13% with a heavy dew in the evening or with a rain.
Balance Between High Moisture and Shatter Loss
Many university researchers and experts suggest starting bean harvest around 15% moisture. You may ask, why so high? At those levels we will take a dock at the elevator! While this is true, there is a very important balance to strike when harvesting beans. Anything harvested below 13% moisture is bushels lost. When you take in a load of beans at 10%, you are not selling as much water as you are allowed to. And even though your test weight isn’t 60 pounds per bushel, your load is still treated as such and will not yeild as much as if your beans were 13%. This chart from the University of Nebraska demonstrates the % potential yield reduction by delivering soybeans when less than 13% moisture.
At 9% moisture you will have a 4.4% yield reduction. At 11%, it is a 2.25% yield reduction. It really comes down to the question, which is better, getting a dock for high moisture? Or a yield reduction from low moisture beans?
Consider the following example.
Your beans are making 70 bushels per acre at a standard 13%.
Example 1:
Harvest moisture: 14%
Price dock: 3%
Actual price: $7.45
If you were to try to sell corn at 14% moisture, the 3% dock would give you a price of $7.22 per bushel.
70 bushels per acre yield x $7.22/bu= $505.86 per acre gross
Example 2:
Harvest Moisture: 9%
Yield Reduction: 3.3%
Actual Price: $7.45
If you were to harvest and sell corn at 9% moisture, the 4.4% yield reduction would result in 3.08 bushels per acre less than if harvested at 13% moisture. This means a 66.9 bushel per acre total.
66.9 bushels per acre yield x $7.45/bu= $498.29 per acre gross
In this case, it would be better to take the dock for high moisture corn than harvest at 9% moisture. These scenarios result in a $7.57 advantage for harvesting at high moisture. These results will change based on your circumstances. In this example, if we were considering harvesting at 11%, it would actually be wiser to let the grain dry to that point rather than take the moisture dock. Ideally, we would always harvest at 13%. However, it is unlikely that we will be able to harvest every field at 13%. Since this is the case we have the option to harvest some beans at high moisture, or harvest some below 13% moisture. Check with your elevator and put a pencil to paper for your specific situation in order to find the best solution possible.
Variable Field Moisture
Finally, when field conditions are highly variable, with parts of the field dry and other parts of the field with green stems and pods, it is difficult to know when to harvest. An article from the university of Wisconsin suggests the following options.
1. Harvest the field in two separate groups.
2. If harvesting separately isn’t possible, wait until the entire field can be harvested and risk the possibility of shatter.
3. If shatter is a large concern, harvest sooner to retain as many pods and seeds as possible. Adjust combine settings to get rid of green stems and pods.
Conclusions
Thanks for following along as we learned some info on soybean harvest and what we can do to maximize seed retention and profit. Consider the moisture and color of the plants as they mature, change settings to minimize shatter and harvest losses, and finally calculate the scenario for balancing a dock at the elevator with low moisture soybeans.
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