5 MIN READ

Continuous Soybean Management Practices

August 18, 2025

  • Planting continuous soybean may be an attractive option for some growers because of favorable market prices, lower input costs, and harvesting economics.
  • Soybean yield potential may be reduced because of an increase in disease pathogens, nematodes, and insect pests.
  • Soybean products should be evaluated closely for defensive characteristics such as disease tolerance, standability, and nematode resistance.

Is back-to-back soybean an option?

Continuous soybean production is generally not recommended; however, some farmers have reported stable yields for many years when planting back-to-back soybean crops.1 The decision to plant back-to-back soybean crops is largely based on economics and where soil types favor the continuous production of soybean. Factors to consider for producing continuous soybean crops include field selection, potential soybean diseases, nematode infestations, fertility, and weed management. When comparing the market price for soybean compared to corn along with the input costs for producing each crop, the planting of soybean again might be economically advantageous.

Field Selection

Fields that favor continuous soybean include those not prone to holding excessive moisture and where disease and soybean cyst nematode (SCN) infestations are minor. Low lying fields and fields with poor drainage are not ideal for continuous soybean because of the increased potential for root rots such as Phytophthora Root Rot (PRR) and Pythium. Under these situations, soybean product characteristics should be reviewed closely for tolerance or resistance for root rot diseases. Soybean cyst nematode infested fields can reduce potential yields dramatically if resistant soybean products are not planted.

Disease and Nematode Management

In the constant presence of a host crop, disease inoculum can increase on crop residue and in the soil each growing season. A field with disease or nematode issues may see a dramatic reduction in yield potential after the third or fourth year of continuous soybean production.2 Diseases such as PRR, white mold, sudden death syndrome (SDS), brown stem rot (BSR), and SCN remain in the soil or on crop residue for several years after a host plant is removed. Without crop rotation to break pest and pathogen life cycles, other management approaches are needed. Often, planting a product with disease or insect resistance is the most effective management approach.

  • Phytophthora root rot can be managed by selecting soybean products with race-specific resistance genes (Rps genes) and partial resistance. Rps resistance genes include Rps1a, Rps1c, Rps1k, Rps3a, or Rps1k + 3a. Soybean products with partial resistance have some resistance to all PRR pathotypes. In historical PRR infested fields, soybean products with the combination of the appropriate Rps gene resistance relative to the PRR races in a field and partial resistance should be planted.3 The disease can appear anytime during the season with root rot, stem rot, and defoliation (Figure 1). For additional PRR information, please visit Identification and Management of Phytophthora Root Rot in Soybean.
Figure 1. Phytophthora root rot with characteristic stem discoloration.

  • White mold mycelium or sclerotia are hard black fungal structures that survive in the soil or on soybean residue from year-to-year. In continuous soybean production fields, the disease can be problematic if growing conditions are wet and cool when soybean plants are flowering. The sclerotia germinate near the soil surface and form small mushroom like structures (apothecia) that produce ascospores that move by wind to infect dead soybean flowers. Infection then spreads to the stems where a cottony like mold appears. The infected plants turn grayish green, wilt, and die (Figure 2). Crop rotation out of soybean for two to three years is the best management technique. No soybean products are completely resistant to white mold. Other management techniques may include planting the soybean crop in wider rows and reducing seeding rates to help increase air flow in the canopy.4 Planting later in the season or planting earlier maturing soybean products for the area may help reduce the potential for infection. For additional information on white mold, please visit Understanding White Mold in Soybeans.

Figure 2. Soybean white mold with characteristic cottony fungal growth.
Figure 2. Soybean white mold with characteristic cottony fungal growth.

  • Sudden death syndrome is caused by a soilborne fungus that survives year-to-year in the soil and on residue. Plant infection occurs through the roots of seedling soybean plants; however, visual symptoms are not typically noticed until the early reproductive growth stage (R3). Visual SDS symptoms include yellowish spots between the leaf veins that eventually coalesce to form large yellow areas before becoming necrotic. Tap roots display a rot and may have a bluish fungal growth. Leaf petioles remain attached to the stem as dead leaves drop from the plant. The stem interior is white which differs from the brown interior of BSR. Both diseases have similar leaf symptoms.5 Crop rotation is the best management practice and seed treatments are available for SDS protection. Additionally, there are soybean products available with various levels of SDS tolerance.5 For additional SDS information, please visit Managing Sudden Death Syndrome in Soybean.

Figure 3. Sudden death syndrome with characteristic leaf necrosis and white stem pith.
Figure 3. Sudden death syndrome with characteristic leaf necrosis and white stem pith.

  • The brown stem rot pathogen is another soilborne fungus that survives in the soil and on soybean residue. Like SDS, infection occurs early in the season, but visual symptoms are not usually observed until late summer. Visual symptoms include the browning of the interior stem and possibly the yellowing of leaf tissue between the leaf veins (Figure 4). There are two types of BSR pathogens (A and B). Both types cause pith browning; however, type A also has the potential for leaf yellowing. Management includes crop rotation and the planting of BSR resistant soybean products. Soybean products that include BSR and SCN resistance may be helpful as SCN appears to aid in BSR infections.6

Figure 4. Brown interior pith from brown stem rot infection.
Figure 4. Brown interior pith from brown stem rot infection.

  • Soybean cyst nematodes are the most economically destructive pest for soybean producers with over a billion US dollars of economic loss annually. The pest is a plant-parasitic nematode that feeds and reproduces on soybean roots. Infestation symptoms may not appear until infestation levels reach economic levels. Visual foliar symptoms mimic other agronomic factors such as nutrient deficiencies, compaction, drought, herbicide injury, flooding, and other root and foliar diseases. If roots are examined, small, white to yellow, lemon-shaped structures (females or immature cysts) can be found on the root surface (Figure 5). The cysts can be found on susceptible plants as early as 30 to 45 days after planting.7 Management includes crop rotation, the planting of resistant soybean products, and the use of protective seed treatments. However, resistant soybean products do not provide complete control as they limit SCN reproduction but are still attacked. Additionally, other nematode species may also be present. For additional information on SCN and other soybean nematodes, please visit Parasitic Nematodes in Soybeans.

Figure 5. White to yellowish soybean cyst nematode egg sacs.
Figure 5. White to yellowish soybean cyst nematode egg sacs.

Seed Treatments

Seed treatments are a critical component in continuous soybean production. Broad-spectrum fungicidal seed treatments can help protect soybean plants from early-season root pathogens including Pythium, PRR, Fusarium, and Rhizoctonia. Broad-spectrum insecticidal seed treatments can help protect soybean seeds or seedlings from bean leaf beetle, soybean aphid, seed corn maggot, wireworm, and white grub. Some seed treatments can also protect seedlings against the early infection of SDS and SCN.

Weed Management

Weed management becomes more difficult in continuous soybean production because the practice favors the survival of weeds when herbicides with the same site of action are used year after year. In addition, there is the potential for the development of herbicide resistant weeds. The tank mixing of different site of action herbicides is highly recommended. Residual herbicides should be applied preemergence and potentially postemergence to aid in control of problematic weed species.

Soil Fertility

Nutrient inputs should be based on soil test recommendations, which should be conducted every three to four years. Phosphorus (P) and potassium (K) soil levels should be monitored closely as 1.5 to 3.0 times P and K are needed to produce a bushel of soybean grain compared to a bushel of corn.8 At harvest, more K is removed from the field in the seed compared to corn. In the upper Midwest and the river valleys of central and western Nebraska, and northwest Kansas, iron deficiency chlorosis (IDC) is a common occurrence in calcareous soils with high pH.



Sources
1Davidson, D. 2016. Continuous soybean questions. Dr. Dan Talks Agronomy. Progressive Farmer. https://www.dtnpf.com/agriculture/web/ag/news/article/2016/02/12/continuous-soybean-questions.

2Brhel, J. Specht, J., Elmore, R., Giesler, L., Hunt, T., Irmak, S., Jhala, A., Klein, R., Mueller, N., Shapiro, C., Vyhnalek, A., and Wright, R. 2017. Planting soybean after soybean (part 1): planting considerations. CROPWATCH. Nebraska Institute of Agriculture and Natural Resources. University of Nebraska – Lincoln. https://cropwatch.unl.edu/2017/planting-soybean-after-soybean-part-1-planting-considerations/

3Martin, D. and Dorrance, A.E. Phytophthora damping-off and root rot of soybean. College of Food, Agricultural, and Environmental Sciences. CFAES. PLPATH-SOY-RO3-18. The Ohio State University. https://bpb-us-w2.wpmucdn.com/u.osu.edu/dist/c/44296/files/2017/03/PhytophthoraSoybean_July17-1sk11iq.pdf

4Malvick, D. 2018. Sclerotinia stem rot (white mold) of soybean. University of Minnesota Extension. https://extension.umn.edu/soybean-pest-management/sclerotinia-stem-rot-white-mold-soybean

5Mangel, D. (Updated from Giesler, L.J.) Sudden death syndrome. CROPWATCH. Institute of Agriculture and Natural Resources. University of Nebraska – Lincoln. https://cropwatch.unl.edu/plant-disease/soybean/sudden-death-syndrome/

6Malvick, D. 2018. Brown stem rot (BSR) on soybean. University of Minnesota Extension. https://extension.umn.edu/soybean-pest-management/brown-stem-rot-bsr-soybean

7Bissonnette, K., Faske, T., and Tenuta, A. 2021. An overview of soybean cyst nematode. Crop Protection Network. A Product of Land Grant Universities. https://cropprotectionnetwork.org/publications/an-overview-of-soybean-cyst-nematode

8Stowe, K.D. 2017. Soybean fertility basics. N.C. Field Report. NC Soybean Producers Association. https://ncsoy.org/article/soybean-fertility/

Additional Source

Lauer, J., Porter, P., and Oplinger, E. 1997. The corn and soybean rotation effect. Agronomy Advice. Corn Agronomy. University of Wisconsin Agronomy Department. https://corn.agronomy.wisc.edu/AA/A014.aspx

Web sources verified 4/17/25. 1314_59881