DES MOINES, Iowa, May 20, 2009 - Experts at Pioneer Hi-Bred, a DuPont business, say developing a management plan throughout the crop cycle is key to increasing yields for soybeans. Variety selection, seed treatment and scouting are all important factors in boosting yields, and as the growing season progresses there are actions growers can take to maximize yields.
"With soybeans, it's about trying something different when it comes to crop management," says Ryan Clayton, Pioneer agronomist in southwest Iowa. "Soybeans can respond well to management and become an even more prosperous crop on growers' operations."
Managing soybeans from beginning, seed selection, through harvest is essential. Once a soybean crop is in the ground, weed control and pest and disease scouting is top priority. Options to boost fertility also may be considered at this time.
Many soybean producers depend on residual corn fertility to supply nutrients to their soybean crop. When soils are routinely maintained at high or very high levels of phosphorous (P) and potassium (K), this may be a safe strategy, but often it is not. Some Extension soil fertility specialists have indicated soil test levels of P and K in their states often are not adequate for optimum soybean yields.
Soybean growers also should be aware of their soil pH. A soil pH of 6.0 to 7.0 is considered ideal for soybean production. Liming acid soils or utilizing varieties with good iron deficiency chlorosis scores on high pH soils will help prevent yield reduction.
Soybeans are also high in protein and therefore in nitrogen. Soybeans remove about 4 pounds of nitrogen from the soil for each bushel of grain produced. This compares to less than a pound of nitrogen removed per bushel of corn grain produced. The soybean plant's nitrogen needs usually are supplied by nitrogen-fixing rhizobia bacteria associated with its roots, so adding nitrogen fertilizer usually is unnecessary under normal production practices.
"The importance of obtaining adequate nodulation can't be overemphasized. Always use an inoculant when planting into a field that has not been in soybeans for the past two to three years," says Mike Hughes, Pioneer agronomy research manager. "Failure to achieve adequate nodulation could require supplemental nitrogen in-season to maintain yield."
In studies, foliar feeding increased yields only 15 percent to 20 percent of the time. However, it may be useful when soil nutrients are inadequately supplied, such as production on sandy soils or high-yielding irrigated fields.
"Fertilizer is a bit of a wild card," explains Clayton. "Within the industry, data has been mixed as to whether fertilizing boosts yields. It is, however, always an option to explore."
Weed control also is an important factor in producing high-yielding soybeans. Controlling weeds early allows growers to plant into cleaner, warmer seedbeds for improved stand establishment. DuPontTM Enlite® and EnviveTM herbicides, feature two modes of action that will provide growers with longer-lasting, more consistent early season control of weeds which allows them to apply their postemergence application closer to crop canopy.
"Delaying weed control or using only a glyphosate application could reduce potential yields," says Clayton. "Weeds rob soybean plants of important pod-producing nutrients and sunlight. A two-pass program is recommended."
Along with weed control, scouting for diseases and pests is vital. Scouting once a week until flowering, then scouting twice a week through the intense disease and insect time frames is ideal.
"In certain regions, particularly in the South, scouting takes on a high priority quickly in the growing season," says Hughes. "Once a bean hits the R3 stage, a foliar fungicide application is typical. Diseases like frogeye leaf spot and others are easily controlled with a fungicide and have demonstrated a return on investment. Insects, including various worms and stink bugs, can cause significant yield loss and damage seed quality. They must be controlled in a timely manner."
Other important growing season factors include drainage and irrigation. Fields with poor drainage or standing water for extended periods of time reduces yields. Irrigation, if available, should be used in a timely manner.
"Waiting too long to irrigate can set soybeans back," says Hughes. If a dry spell occurs, and the plant wilts during the day, the bean is set back and may never catch up. Additionally, if it takes a long period of time to make a pass with an irrigation pivot, the beans on the end are going to be stressed, once again reducing yield.
"On the flip side, growers can cut back irrigation too soon as well. Though weather dependant, expect to maintain an irrigation schedule through the R7 stage."
Soybeans should be harvested based on pod maturity and not leaf drop to avoid waiting too long and shattering.
"If a grower is in an area where drydown is slow, a desiccant can be applied to speed up that process," says Hughes. "Sometimes it costs more to wait for the bean to drydown, losing yields, than to take some dockage at the elevator for moisture."
Other key factors to raising high-yielding soybeans is choosing the right variety, selecting for relative maturity, key environment and traits. Though growers will be selecting products for next year at a later time, keeping an eye on performance of this year's crop can provide guidance.
"It's important to select the right variety for specific fields," says Hughes. "It's not about picking the highest-yielding variety in a trial or choosing a variety that yielded well for a neighbor; it's about choosing a variety on a field-by-field basis that will perform well in a particular environment based on specific soil conditions and insect and disease pressures - putting the right product on the right acre."
Planting date is important. Earlier planting allows for more days of flowering, increasing the number of pods or seeds.
"Planting early allows the bean plant to take advantage of longer days for optimum flowering," says Clayton. "Increasing the days of flowering allows for more pods which boosts yields."
Seed treatments also have become increasingly popular, providing growers added protection. This type of protection offers yield stability. Growers not using seed treatments should boost planting rates by 10 percent to 15 percent.
"Several quality fungicide and insecticide seed treatments are available and should be considered," says Hughes. "Seed treatments help provide protection for early diseases and pests when planting into cooler and wetter soils."
According to Pioneer data, soybean yields increase 1.8 percent each year while corn yields, on average, increase 2 percent each year.
"It's about developing a management plan and following through with it from start to finish. Higher yields at harvest time will show how those efforts paid off," says Clayton.
For more information about Pioneer soybeans, visit www.pioneer.com/soybeans. To learn more about managing soybeans for higher yields, contact your local Pioneer sales professional or agronomist.