Soybeans are a very big crop in the United States, especially in the upper mid-west where about 80% of US soybeans are grown. These nutritious, versatile legumes can be used for a wide variety of purposes ranging from creation of bio-fuel to food and industrial and personal care products. In this article, we provide an overview of the considerations you should keep in mind when considering planting soybeans. Read on to learn more on how to grow soybeans commercially.
What You'll Learn Today
- Why Grow Soybeans?
- How Do You Plant Soybeans?
- How Do You Choose The Best Soybean Seed?
- When Is A Good Time To Plant Soybeans?
- Corn & Soybeans Are Good Companions
- How Do You Harvest Soybeans?
- Your Job Is Not Done When Harvest Is Over
- Frequently Asked Questions
Why Grow Soybeans?
Soybeans come from East Asia, but these days most soybeans are grown in South America and in the US.
In addition to their innate value as a productive crop, soybeans are especially desirable as a rotation crop.
Grown in rotation with corn, wheat and other crops, soybeans add valuable nitrogen to the soil and provide the variety necessary to break weed, insect and disease cycles.
To find out more about soybeans and nitrogen, see this article.
Soybeans are a popular production crop that provides a good value because they contain about twice as much protein as any other grain or vegetable crop.
Additionally, the oil they provide can be used as fuel, or with proper processing, as an additive to a wide variety of edible and personal care products.
How Do You Plant Soybeans?
Soybeans (aka: Edamame) are legumes and are members of the bean and pea family. They can do quite well in any sort of well draining soil in a setting that provides full sun.
Although soybeans can do well in poor soil with a pH level of 6.5 or greater, and will actually improve the condition of any soil in which they grow, it is a good idea to amend very poor soil with a balanced organic fertilizer or compost before planting.
One of the most important considerations when planting soybeans is the depth of planting. To determine how deeply you should plant your beans, you’ll need to think about the tillage method you will be using, as well as your soil moisture and temperature.
With the no-till method, you may plant your soybeans as deep as two inches. With a standard tilling method, planting depth can vary from one inch to an inch and a half in average soil.
In dry soil or sandy soil, planting at a depth of two inches is recommended.
Soybean Growth Stages
Seed soybeans can be simply hand cast over the surface of tilled soil and then lightly tilled to cover them.
Alternately, they can be neatly planted in rows. This method is necessary when using the no-till method of planting. In this case, seeds should be planted 2″ deep and a minimum of 5’ apart.
Read this for more information on planting soybeans without a planter.
Bear in mind that close observation is important in disease and pest prevention, so you’ll want to have enough space between your soybean rows to be able to walk the fields and examine the plants carefully.
Even though, rows can be as close together as 5″ for the growth of the soybeans, but this may make accessing your plants a little difficult. Having rows about 15″ apart makes access easier.
All in all, 15″ rows also seem to work best for soybeans in terms of good yield, but when deciding how far apart to space soybean rows, you also have to keep climate in mind.
In very humid locations, soybeans that are placed too close together may tend to develop problems such as white mold.
In this case, it’s better to place your rows 20-30″ apart, even though this may mean a reduction in yield as great as 3 bushels per acre.
How Do You Choose The Best Soybean Seed?
To ensure the best soybean crop, you must choose your seed carefully. It must be suitable for your climate and your soil conditions.
Think about the history of the field you have in mind and the projected planting dates for your area. Also consider the need for seed soybeans that have been pre-treated with a pesticide and/or fungicide.
If the field you plan to plant has had a history of disease affecting seedlings, seed that has been treated with fungicide can be very helpful.
Furthermore, if the soil has a known history of Sudden Death Syndrome or Phytophthora, a fungicidal treatment of the seeds can make all the difference in the success of your crop.
Even without these challenges, you may want to purchase seed soybean that has been treated with a fungicide if you plan on planting early in the spring while the soil is still cool and wet. These conditions are conducive to fungal growth.
If you are using the no-till method of planting, your soil will stay cooler and moister for a longer period of time. This, too, will make a fungicidal treatment desirable.
On a similar note, if the field you plan to plant has a history of being plagued by insect pests, you will naturally want to purchase seed that has been pre-treated with an insecticide.
Although pre-treated seed may be a bit more costly at the outset, keep in mind that you can plant less seed per acre if it is pre-treated because you are sure to have a better yield.
Untreated seed should be sown at a rate of 150,000 – 170,000 seeds per acre. You can reduce this amount by as many as 20,000 seeds per acre if the seed is pre-treated with fungicide/pesticide.
When Is A Good Time To Plant Soybeans?
It’s hard to set exact dates for planting soybeans. This warm season crop is not frost tolerant, so the timing of planting is important to avoid crop loss due to low temperatures.
Soybeans can be planted at any time from late in the spring time to early in the summer months.
The most important factors to keep in mind are the weather conditions and the soil condition. An early planting date can mean a higher yield, but there are risks involved, as mentioned above. Soil that is too cool and moist can be subject to fungal infection.
Ideally, soil temperatures should be reliably higher than 60 degrees Fahrenheit at the time of planting, but it is possible to plant a successful crop when the soil is a reliable 50 degrees Fahrenheit.
Just be sure that all danger of frost has passed because your soybean seed should germinate within a couple of days, and seedlings will emerge within a week to ten days.
If you plant too early, a sudden frost could kill off your whole crop. For more on germination of soybeans, see our article.
In the upper mid-west, farmers typically plant soybeans in a time period ranging from the last week of April into the middle of May. Waiting until late May can cause a reduction in yield.
It is possible to plant in early April in the upper mid-west, but as noted above, there are risks involved in planting early. When it works out, early planting can boost yield significantly.
In fact, it is possible to get as many as ten extra bushels of soybeans per acre by planting early using full-season soybeans.
Luckily, seed treatments such as fungicides and insecticides make early planting much more likely to succeed than in the past.
For more on how late you can plant soybeans, see our article here.
Corn & Soybeans Are Good Companions
Very often, farmers plant soybeans and corn, and this can cause quite a bit of trouble in terms of planning exactly when to plant both crops while dealing with spring rains.
Corn is pickier than soybeans, so it’s timing must be just right. Soybeans are more resilient and flexible, so farmers who plant both corn and soybeans typically plant treated soybeans early and then focus on the corn once weather conditions are more ideal.
If you are already planting corn commercially, you already have everything you need to plant soybeans commercially.
A few minor adjustments are needed, but for the most part, the same equipment can be used for both crops.
One of the most important aspects of soybean growing is planting the seed at the right depth. Corn planters actually do a better job of this than grain drills, so if you have corn planting equipment on hand, you are ahead of the game.
How Do You Harvest Soybeans?
If you are just growing soybeans for the purpose of improving your soil, you don’t have to wait for the beans to mature.
When the plants start flowering, you can chop them down. The nitrogen nodules left on the roots of the plants will continue to improve and enrich the soil.
When your soybeans are deep green and swollen, they are ready to be harvested for eating fresh. This type of harvesting is typically done by hand.
If you want to harvest them for processing, you may wish to wait a bit longer because very wet soybeans are tough, can damage harvesting equipment and will increase the amount of fuel necessary for harvest.
When harvesting large amounts of soybeans commercially, you’ll want to wait until about 95% of the pods are tan and test at about 13% moisture level. This is the perfect level to prevent having the pods split or shatter when machine harvested.
Your Job Is Not Done When Harvest Is Over
Once your crop has been harvested, you’ll need to start preparing right away for next year’s crop. If you are rotating crops, you’ll want to check the nutrient levels of fields that have not been planted in soybeans.
You may find that the pH level is too low for optimum soybean growth. If it’s lower than 6, you must treat the soil with lime to raise the pH level.
What Can You Do About Weeds, Diseases & Pests In Soybean Fields?
Weeds are the most problematic early in the season because weeds like open air and lots of sun. Mature soybeans block the sun and prevent weed growth.
You’ll have less trouble with weeds using the no-till method of cultivation because the natural mulch of previous years’ soybean crops will smother weed growth.
If you till your soybean field and have bare soil exposed, weeds will want to grow there. In this case, you’ll need to weed by hand and/or use an herbicide to battle weeds within a month of planting a “Round-Up Ready” soybean.
Choosing the correct type of seed soybeans and using an effective herbicide can help prevent problems such as:
- White Mold
- Brown Stem Rot
- Soybean Cyst Nematodes (SCN)
- Iron Deficiency Chlorosis (IDC)
- Sudden Death Syndrome (SDS)
Regular examination of your plants can help you keep ahead of these problems. You’ll want to keep abreast of pod growth while watching for nutrient deficiencies and signs and symptoms of pests and diseases.
Tasks you will need to perform regularly include taking tissue samples to test for nutrient deficiency and providing plants with supplemental nourishment, such as sulfur and potassium.
What Other Hazards Do Soybeans Face?
Japanese beetles love soybeans, and so do deer. Planting seed soybeans that have been treated with pesticide will help keep the Japanese beetles away. Putting up a 5 strand electric fence around your soybeans will help keep the deer out.
Be advised that serious deer hunters often plant soybean food plots as deer forage. This is a good way to maintain a healthy deer population and improve meat quality while simultaneously improving the quality of your soil.
This video discusses this practice and also provides information about the difference between hand casting seed and planting using a drill, along with information about weed control.
Frequently Asked Questions
Soybean plants may experience slow growth because of nutrient deficiencies, environmental stressors, pest or disease infestations, inadequate water availability, or incorrect temperature conditions. These factors may make it hard for the plants to take up nutrients and perform essential metabolic processes. This causes stunted growth.
On a healthy soybean plant, the nodules are usually small, round structures attached to the roots. They can vary in size and color, ranging from pink to light red. Healthy nodules mean that the desired symbiotic relationship between the soybean plant and nitrogen-fixing bacteria (Rhizobia) is well established.
Acidic soil conditions (low pH) below 5.5 can inhibit nutrient availability, particularly phosphorus and micronutrients like iron and zinc, leading to nutrient deficiencies. Similarly, alkaline soil conditions (high pH) above 8 can restrict nutrient uptake, resulting in deficiencies of essential elements like iron, manganese, and phosphorus. These imbalances can hinder soybean growth and reduce crop yield.
Slow-growing soybean plants may benefit from a nitrogen treatment if the cause of slow growth is determined to be nitrogen deficiency. Nitrogen is a crucial nutrient for plant growth and plays a vital role in various physiological processes, but lack of nitrogen is not always the problem with slow growth. It’s important to diagnose the specific cause of slow growth accurately before applying any treatment. Talking with agricultural experts or conducting soil tests can help determine what you need to do.
Soybeans, wheat, and corn do have similar nutrient requirements, but the fertilizer products used for each crop should be tailored to the crops’ specific needs. Soybeans have distinct nutrient uptake patterns and optimal nutrient ratios compared to wheat or corn. For this reason, you should use fertilizers specifically formulated for soybeans to provide the ideal balance of macronutrients (nitrogen, phosphorus, potassium) and micronutrients necessary for their growth. Using the same fertilizer products randomly without considering your crops’ specific requirements can cause diminished nutrient availability and may affect crop yield and quality.