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Getting the Most Out of Soybean Yield Potential

Key Points

  • The foundation upon which all management decisions should rest is product selection.
  • Use of the best-suited product along with proper fertility management and planting practices for your operation can set the stage for optimum yield potential.
  • Finding ways to alleviate stress from weed competition, soybean cyst nematode, insects, and diseases is key to reaching maximum yield potential on your farm.

Many factors interact to determine soybean yield potential. While some of these are beyond our control, there are numerous ways in which growers can use proper management to maximize yields. The foundation upon which all management decisions should rest is product selection. Use of the best-suited product along with proper fertility management and planting practices for your operation can set the stage for optimum yield potential. The next step is stress management. Finding ways to alleviate stress from weed competition, soybean cyst nematode, insects, and diseases is key to reaching maximum yield potential on your farm. Finally, step back to evaluate your management practices and inputs to see what is working and consider ways to improve your operation.

Setting the Stage

Product Selection. When choosing the right soybean product for your particular needs, be sure to consider both the product and the field it will be planted. Keep in mind the history and characteristics of each field when identifying the ideal genetics and traits for each situation. Be sure to consider products that will make the best use of the growing season in your geography. Selection should be based on the best genetic and trait package available for your desired maturity group considering factors such as standability and disease and nematode tolerance.

Planting Date. Research has shown that planting date may be one of the most important factors in yield determination. The greatest benefit of early planting is an increase in yield potential which has been attributed to a quicker crop canopy earlier in the growing season. This allows for better use of the sun’s radiation throughout the growing season prompting plants to produce more nodes on the main stem thus increasing the potential for more pods per plant. Early canopy closure also helps to conserve soil moisture.

Planting Conditions. Soybean seed should be planted 1 to 1.5 inches deep into a moist seedbed with good seed-to-soil contact for germination to occur. Soybean seed can begin the germination process when soil temperatures are around 50° F, but it is recommended to plant when soil temperatures at seeding depth are in the 50’s and trending upward. If early planting is considered, be sure that proper soil and seedbed conditions exist. Planting in soil that is too wet can result in poor seed placement and stand establishment, and compaction. If soybean seeds are planted into soil that is too wet the negative effects will likely outweigh any possible yield advantage from early planting.

Row Spacing. Another useful tool to help ensure earlier canopy closure and its associated benefits is the use of proper row spacing. Research has shown that using row spacing narrower than 30 inches can help improve yield potential. This is especially important for soybeans with high yield potential because early in the growing season the soybean plant needs all the resources it can get to support developing flowers and pods. Another benefit of the earlier canopy closure associated with narrow row spacing is decreased weed competition due to the soybean canopy intercepting light before it can reach developing weed seedlings. In 15-inch row spacing, canopy closure will often occur 15 days earlier than with 30-inch rows which is crucial because canopy closure is necessary by the start of pod set.

Planting Population. Higher plant populations can help contribute to higher soybean yields under the proper circumstances, but depends on row spacing, relative maturity, and planting date. Greater seeding rates are usually required to achieve a higher target population as final plant population depends on seedbed conditions, planter settings, environmental conditions, and pest pressure. Consult your Channel Seedsman for recommendations for your specific planting situation.

Nutrient Management. As soybean yield potential increases, the need to manage soil fertility becomes essential. Soil sampling is an important part of a nutrient management plan to determine soil pH and the amount of soil-available nutrients. A soil pH of 6.5 is ideal for proper nutrient availability for soybean plants.

Although soil tests can provide a good idea of the amount of most nutrients needed, they do not provide an accurate picture of the amount of nitrogen (N) needed. Because soybean plants can acquire up to 75% of their N requirements from the air when N-fixing bacteria are active on soybean roots, it is important to first determine whether there is a presence of the N-fixing bacterium, Bradyrhizobium japonicum, in the soil. In general, if a soybean crop has not been grown in a field for three to five years or more, seed inoculation is recommended.

The remainder of the N must come from the soil or supplemental N provided to the plant. Growers may consider supplementing N on the most productive fields or in cases where the following conditions may warrant its use: soil is light colored/eroded/compacted or has a pH lower than 5.5, crop shows N deficiency symptoms, or active nodules cannot be found on roots. Efficiency of the nodules providing N to the plant tends to decrease during the later reproductive growth stages when N requirements are high. If supplemental N is needed, half can be applied before flowering begins and the rest at the beginning of pod filling to help assure the availability of N at critical stages.

Stress Management

Stress management is one of the biggest obstacles that growers face along the road to improving soybean yield. Stress can appear in the form of weeds, insects, diseases, nematodes, and a whole host of environmental factors. While a soybean crop seems to tolerate short periods of stress better than other crops, any extended stress as plants reach reproductive stages impacts the ability of plants to recover and salvage yields.

Weed Control. Soybean plants are relatively resilient in terms of weed competition, but yield loss due to inadequate weed control still occurs. For optimum weed control, manage weeds early and completely using Roundup Ready PLUS® Crop Management Solutions. Begin with a pre-emergence program, followed by a post-emergence program that controls herbicide-resistant weeds. Be sure to consider proper timing and application rates and use herbicides with residual activity and multiple modes of action when possible. For best results, eliminate weeds prior to planting and control new weeds when they are small. Scout and monitor fields throughout the season to ensure weed control. Consider rotation to other crops in future seasons to allow for the use of different weed management and cultural practices. For more information about weed management solutions, visit www.roundupreadyPLUS.com.

Pest and Disease Control. Insects, diseases, and nematodes can all have a negative impact on soybean yields. Because these can vary greatly across different geographies and field environments, the best place to start is to understand the risk factors for your particular farm and record what pests and diseases are becoming problematic throughout the growing season in your area. For example, soybean cyst nematode (SCN) is a pest that cannot be eliminated from a field once established. By identifying the presence of SCN in a field and understanding management practices to help control nematode populations, you can help protect yield potential in fields infested with SCN.

Scouting. Monitor fields for pests and diseases throughout the season and consult your Channel Seedsman about treatment thresholds and product resistance. Scouting can be done by walking a random path through the field and stopping at various locations throughout to look for weeds, insects, damaged leaves, and plant disease or nutrient deficiency symptoms. Record your findings for reference later in the season as well as during successive seasons. Scouting for insect infestation and damage should continue through the R7 (beginning maturity) stage as yield-robbing insects such as bean leaf beetles and two-spotted spider mites may still warrant control through seed fill.

Where treatable problems are identified, consult your Channel Seedsman for tips using the appropriate herbicides, fungicides, or insecticides. Consider the use of seed treatments to help protect seeds and seedlings from fungal pathogens, nematodes, and insect pests.

(Source – https://www.channel.com/agronomics/Pages/Getting-the-Most-out-of-Soybean-Yield-Potential.aspx)

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