By Dr. Harold Willis
As soybean seeds lose moisture they change from large, kidney bean shaped to smaller and nearly round. When dry, the seed contains about 40% protein, 21% oil, 34% carbohydrates and 5% ash.
There is an amazing number of soybean varieties. Just about every valley in China, Japan and Korea grows its own variety, adapted to local conditions. A collection of over 10,000 strains of soybean seeds is maintained by the USDA. A glance of an assortment of these seeds reveals seeds of every color and description—some red, some green, some black, some brown, some speckled or streaked, some large and some tiny.
The great majority of soybean varieties grown commercially today is for animal feed and oil production (for food processing and industrial uses). Most are yellow-seeded field varieties. Other varieties can be obtained for special uses: forage and hay (with an abundance of stems and leaves; small-seeded black and brown late varieties) and human food (large-seeded, various-colored varieties).
Selecting a Soybean Variety
In selecting which variety you wish to plant, assuming you are growing field soybeans, you need to consider several things. First, buy the best quality seed you can find. Certified tested seed is usually worth the cost. You can test for germination rate by counting out 25 whole seeds and roll them up in a damp cloth. Keep in a warm (70 to 80 degrees F.) place. Sprinkle with water if necessary to keep the cloth moist. After five or six days, unroll the cloth and count the seeds that have germinated out of 25. Multiply by 4 and divide by 100 to get the percentage germination.
Be sure to get seed of a Maturity Group adapted to your area. You may want to vary slightly the maturity group depending on soil type (an early variety for cool, wet, fine-textured soils and a later variety on coarse, well-drained soils). Avoid early varieties in fields where tall broadleaf weeds may get out of hand. If you want to follow the soybeans with fall-seeded small grains, use an early-maturing soybean.
One way to allow for uncertain weather conditions is to plant more than one maturity, either in different fields or as a seed blend, a mixture of varieties. That way at least one variety should give a reasonably good yield. If you save your own seed to replant, you will not get the same proportion as what was in the blend.
Select a variety that is shatter and lodging resistant, especially if you intend to plant high populations, since the plants will grow taller, more slender stems.
Disease and insect resistance may be important if these have been a problem in your area; however, by improving your soil’s fertility and structure, most such problems should disappear.
Indeterminate varieties should be used in the North, and determinate varieties do not do well in soils that crust. For wide rows, bushy varieties are best, to fill in the space quickly.
If you use a grain drill for planting, avoid seed lots with many large seeds, which do not flow well through the drill. Use seed lots with 2,400 seeds per pound or less. Small-seeded varieties have some advantages: the seedlings emerge better through crusted soil, fewer pounds of seed are needed to establish a certain plant population, and it is often easier to produce high quality grain (because smaller seeds suffer less damage during harvesting and handling).
You can often get valuable advice on selecting varieties from your agricultural research and extension personnel or from seed dealers. They may have performance test results which can be a rough guide of what to expect from a variety.
Measuring Soybean Seed Quality
Varieties are developed to produce high yields of good quality seed, to mature properly for the geographic area, to be resistant to lodging and shattering, to be cold and drought tolerant, and to resist diseases and pests.
Factors of seed quality may include low numbers of defective or shriveled seeds, high germination rate, high oil and/or protein content and human food value.
Soybean seeds sold by reliable seed dealers should come with certain important information: the variety, the Maturity Group number, percent inert matter, percent weed seed, percent other crop seed, germination rate and resistance to diseases and/or pests. The U.S. Plant Variety Protection Act of 1970 and the earlier Federal Seed Act, as well as state seed laws, provide standards and protection to dealers, but some private growers may not adhere to these standards. Anyone can save some seed to grow the next year, but this is no assurance of quality.
What are Hybrid Soybeans?
Commercial hybrid soybean seed is very difficult to produce. This is because of the way the soybean reproduces: it is self-pollinating. Hybrids are made by soybean seed breeders, but it is a laborious, expensive process. From various ancestral and hybrid varieties, the commercial varieties are developed, both by agricultural experiment stations and private seed companies.
Edible Soybean Varieties
Varieties of soybeans suitable for human food can be obtained from garden seed companies and stores. If you do not want to grow your own, various forms of soybean products can be purchased from health food stores.
Akita Early. Mature beans are yellow. Fresh beans are ready in 65 days after planting, dried beans in 95 days.
Altona. A good northern variety. Beans are yellow with a black “eye.” Fresh beans in 70 days, dried beans in 100 days.
Envoy. A northern variety. Beans are green. Fresh beans in 70 days, dried beans in 104 days.
Meredith. A northern variety. Beans are small and yellow. Fresh beans in 80 days, dried beans in 110 days.
Oriental Black. Mature beans are black. Fresh beans in 70 days, dried beans in 100 days.
Panther. A black, highly digestible variety. Fresh beans in 85 days, dried beans in 115 days.
Prize. A tall variety with large beans adaptable to most areas. Fresh beans in 85 days, dried beans in 115 days.
Traverse. A yellow-beaned northern variety. Fresh beans in 81 days, dried beans in 111 days.
Try to buy varieties adapted to your area. Early varieties do best in the north, and medium or late varieties in the south.
Growing edible soybeans for the commercial market or for local restaurants, health food stores, or tofu makers is an excellent way to greatly increase your per-acre income. Harvesting fresh (green) soybeans cannot easily be done by machine, however, so it would be a labor-intensive crop.
Source: How to Grow Super Soybeans