NDSU Offers Advice on Drying Soybeans

Oct 15, 2018

By Ken Hellevang

Figure 1. High moisture conditions are leading to high moisture soybeans, complicating drying and storage efforts.

A challenging soybean harvest is creating many questions related to storage and drying, according to Ken Hellevang, agricultural engineer with the North Dakota State University Extension Service.

Soybeans at 11% moisture have storage characteristics similar to wheat or corn at about 13.5% moisture, so 16% moisture soybeans might be expected to store similarly to about 19% moisture corn. It is important to be able to aerate the soybeans to keep them cool.

The amount of natural air drying that will occur in late October and early November is limited. The equilibrium moisture content of soybeans for air at 40°F and 70% relative humidity is about 12%. With this air condition drying should occur with soybeans above 12% moisture. However, the drying rate will be slow at typical in-bin drying airflow rates. An airflow rate of 1 cubic foot per minute per bushel (cfm/bu) is expected to dry 18% moisture soybeans in about 60 days. With an airflow rate of 1.5 cfm/bu the drying time is reduced to about 40 days. The drying time for 16% moisture soybean is slightly less. The drying time of 16% moisture soybeans is about 50 days. Adding supplemental heat to raise the air temperature by 3 to 5 degrees will permit drying the soybeans to about 11% moisture in about 40 to 45 days. Increasing the airflow rate proportionally reduces the drying time.

The moisture holding capacity of air is reduced at lower air temperatures. As average air temperatures approach 35°F, natural air drying becomes inefficient and not economical.

Figure 2. Extensive rainy, wet conditions in areas of Nebraska are leading to soybean pods popping open, further complicating this year's harvest.

The moisture-holding capacity of air is reduced at lower air temperatures. As average air temperatures approach 35°F, natural air drying becomes inefficient and is not economical.

Adding heat would cause the beans on the bottom of the bin to be dried to a lower moisture content and it would increase drying speed only slightly. Cool the soybeans to between 20°F and 30°F for winter storage and complete drying in the spring. Hellevang recommends starting drying in the spring when outdoor temperatures are averaging about 40°F.

Increasing the airflow rate will increase the drying speed. However, the fan horsepower required to achieve the higher airflow rate becomes excessive unless the grain depth is very shallow. For a soybean depth of 22 feet, each 1,000 bushels of soybeans will require about 1.0 horsepower of fan. Achieving an airflow rate of 1.25 cfm/bu will require about 1.6 horsepower per thousand bushels and an airflow rate of 1.5 cfm/bu will need about 2.5 horsepower per thousand bushel.

The type of fan greatly affects the airflow provided per horsepower, so use a fan selection software program such as the one developed by the University of Minnesota. It is available on the NDSU Grain Drying and Storage website.

Soybeans can be dried in a high-temperature dryer, but the plenum temperature needs to be limited to minimize damage to the beans. Refer to the manufacturer’s recommendations for maximum drying temperature. Typically the maximum drying temperature for nonfood soybeans is about 130°F. Even at that temperature, some skins and beans will be cracked.

One study found that with a dryer temperature of 130°F, 50% to 90% of the skins were cracked and 20% to 70% of the beans were cracked. Another study found that 30% of the seed coats were cracked if the drying air relative humidity was 30%. Roughly with each 20-degree increase in drying temperature, the air relative humidity is reduced to one-half. When air at 50°F and 80% relative humidity is heated to 70°F, the relative humidity drops to about 40%. Monitor the soybean seeds coming from the dryer and manage the dryer temperature based on the amount of damage occurring.

Caution

There is a risk of fire when drying soybeans. Soybean pods and other trash can accumulate in the dryer and become combustible. Clean the dryer frequently to ensure trash does not build up and to reduce the potential for debris becoming combustible. Also, assure that soybeans continue to flow in all sections of the dryer. Monitor the dryer continuously to limit fire potential.

Source: unl.edu

Video: Moving Ag Research Forward Through Collaboration

BY: Ashley Robinson

It may seem that public and private researchers have different goals when it comes to agricultural research. However, their different strategies can work in tandem to drive agricultural research forward. Public research may focus more on high-risk and applied research with federal or outside funding, while private sector researchers focus more on research application.

“For me, the sweet spot for public private sector research is when we identify problems and collaborate and can use that diverse perspective to address the different aspects of the challenge. Public sector researchers can work on basic science high risk solutions as tools and technologies are developed. They then can work with their private sector partners who prototype solutions,” Mitch Tuinstra, professor of plant breeding and genetics in Purdue University’s Department of Agronomy, said during the Jan. 10 episode of Seed Speaks.

Public researchers they have the flexibility to be more curiosity driven in their work and do discovery research. This is complimentary to private research, which focuses on delivering a product, explained Jed Christianson, canola product design lead for Bayer CropScience, explained during the episode.

“As a seed developer, we worry about things like new crop diseases emerging. Having strong public sector research where people can look into how a disease lifecycle cycle works, how widespread is it and what damage it causes really helps inform our product development strategies,” he added.

It’s not always easy though to develop these partnerships. For Christianson, it’s simple to call up a colleague at Bayer and start working on a research project. Working with someone outside of his company requires approvals from more people and potential contracts.

“Partnerships take time, and you always need to be careful when you're establishing those contracts. For discoveries made within the agreement, there need to be clear mechanisms for sharing credits and guidelines for anything brought into the research to be used in ways that both parties are comfortable with,” Christianson said.

Kamil Witek, group leader of 2Blades, a non-profit that works with public and private ag researchers, pointed out there can be limitations and challenges to these partnerships. While private researchers are driven by being able to make profits and stay ahead of competitors, public researchers may be focused on information sharing and making it accessible to all.

“The way we deal with this, we work in this unique dual market model. Where on one hand we work with business collaborators, with companies to deliver value to perform projects for them. And at the same time, we return the rights to our discoveries to the IP to use for the public good in developing countries,” Witek said during the episode.

At the end of the day, the focus for all researchers is to drive agricultural research forward through combining the knowledge, skills and specializations of the whole innovation chain, Witek added.

“If there's a win in it for me, and there's a win in it for my private sector colleagues in my case, because I'm on the public side, it’s very likely to succeed, because there's something in it for all of us and everyone's motivated to move forward,” Tuinstra said.