Dennis Lange, Provincial Pulse Specialist, Manitoba Agriculture and Resource Development – Summer (June) Pulse Beat 2020
Every year I get calls from dry bean growers on harvesting challenges. These questions range from how do I reduce splits to how to reduce earth tag, just to name a few. Looking back through an old Pulse Beat, I discovered it had been 20 years since I wrote a similar article on combine modifications for dry beans. In this discussion, I will be referring to some of the same equipment, but focusing more on improving the overall dry bean quality.
Not all Dry beans are Created Equal
Some bean types require extra special handling due to their brittle nature, especially when seed moisture is 10–12%. Harvesting navies, blacks and pintos can be done with conventional or rotary combines. Kidney, cranberry, pink and Great Northern beans have a much better fit for a specialty bean combine. This type of combine can handle those bean classes when harvest conditions are more challenging. Keep in mind, when harvesting beans, a lot depends upon operator experience as well. I have seen growers harvest kidney beans with a rotary combine and deliver beans that look just as good as if they were harvested with a bean combine. I have also seen the opposite where the grower should have hired a bean combine due to the high amount of damage created under the more challenging harvest conditions. For this discussion, I will focus on tips for conventional and rotary combines.
Basic Equipment Modifications
What types of equipment modifications should you consider for harvesting beans if using a conventional or rotary combine? Screen kits placed in strategic locations are vital to helping eliminate soil. It is best to start at the header and under the feeder house. Eliminating soil before it goes into the hopper is very important. Some growers have also installed screen kits on the unloading auger. That does help to remove some soil, but smearing can still occur if moisture from soft puffy (not fully mature) beans or green plant material combines with soil and smears the beans. The use of a conveyor mounted on the combine to unload the beans will also help reduce the smearing of those beans.
Soft, Puffy, Smeared Beans
Continuing on this topic of soft, puffy, smeared beans, how do you eliminate those beans from the sample? You could wait until the beans dry down to continue to harvest, but they are probably already at 16% moisture. Waiting for the soft bean to dry down will cause the overall sample to get too dry and make it challenging to keep your splits and cracked seeds low. If you keep these beans from earth tagging, then they will dry down normally in the bin. The first thing to do is to check the back of the truck after the first combine dump to see if there are any smeared beans. If the beans are clean but soft, then you are good to go. They will dry down normally in the bin. If the beans are smeared, it will count as pick or damaged and will be discounted when you deliver them. What I would suggest, is to find out how the soil is coming into the combine. If these beans are undercut, have they been windrowed? That helps to remove any soil clinging to the roots. The best way to remove soil is by using screen kits under the feeder house early in the process. Increasing fan speed can help a bit, but if the soil is moist, then higher fan speed will not help. If you are direct-harvesting beans, this allows for a cleaner sample as long as you are not picking up soil by improper header adjustments.
What if your beans are too dry?
If your beans are under 12% moisture, the first thing you should do is check to see if you are getting more than 10% cracked seeds. A quick way to check is to grab a sample from the hopper and soak 100 seeds in a small pan of water. If you pick out 10%, then a few adjustments will be necessary. Keep in mind that for navy, pinto and black beans, the 10% rule would apply to most bean company requirements. However, for the larger bean types like kidney and cranberry beans, which are more sensitive to cracks, the lower you can keep your cracks the better. To reduce cracks, you should start by first reducing your cylinder speed. Starting speeds are around 300–600 rpm depending on bean type and harvest conditions. If you’re starting at 500 rpm, then reduce your rate in 100 rpm intervals until you see a noticeable difference in cracks. If you do this and not much changes, then try to close up your concave to thresh the beans out quicker. Having your concave too far open will allow the beans to flow further into the threshing system, causing the rotor to hit the beans and create more cracks.
If you are a first-time bean grower, make sure you have a bean concave, also known as a wide-wire concave, installed on your combine. That will allow the beans to fall through the concave faster. The amount of material entering the combine also plays a role in keeping cracked seed low. If you can, keep more material in the combine by windrowing beans into larger windrows. Or if you are straight-cutting, a wider cutting width will help keep the combine running at full capacity. That helps to cushion the beans, thus reducing splits and cracks.
The time of day you are harvesting also makes a difference. I recommend harvesting when the plants are dry and avoid harvesting before noon. If you try to harvest when the plant material is moist, the beans may be dry but the pods do not open up as quickly when going through the cylinder and concave. They actually crack and split more than if the plants are dry. The same applies to harvesting in the evening. At sunset, you should be monitoring your cracks closely. I have seen instances where growers have harvested kidneys during the day at 13% moisture with 2% cracks, then cracked seed jumped to 30% by evening. This caused marketing challenges for those beans.
Pods and Soybeans in the Sample
Pods are relatively easy to address. If there are unthreshed pods in the sample and those pods are green, then the beans are not ready to harvest. If the pods are mature and open, then closing up your sieves and increasing your fan speed should help.
The final comment is on soybean admixture. There is nothing you can do to remove soybeans from a dry bean sample with the combine. If you notice the odd soybean in your field before harvest, try to harvest that dry bean field earlier than other fields. I have seen growers harvest dry beans with a few green immature soybeans in the sample and the buyers have still been able to work it because the green soybeans typically shrink up. That is tricky to do because both soybeans and dry beans are long-season crops and both mature in September. A safer option would be to contact your bean buyer and let them know before delivery so that they can address the situation before the beans arrive at the processing facility.