Why are some soybean fields badly lodged this year?

Environmental and management practices that contribute to lodged soybeans in 2014 and recommendations for reducing lodging in the future.

Severely lodged soybean field.
Severely lodged soybean field.

Several factors combined to increase lodging in soybean fields in Michigan this 2014 summer. The first contributing factor was the later than normal planting dates. Soybeans planted in mid-May to mid-June have been shown to be taller than soybeans planted before mid-May or after mid-June. The most significant environmental factor was the frequent and sometimes heavy rainfall events occurring during the growing season. Excessive rainfall or irrigation during the vegetative growth stages increases the length of the internodes and overall plant height in soybeans. High winds also contributed to this year’s lodging. This was the case in the field depicted in the photo as all the plants are lodged in the same direction.

The other management factors that contribute to lodging in soybeans are high plant populations, highly productive soils such as muck and lake-bed soils, low potassium soil test levels and planting varieties prone to lodging. The variety planted in the field shown in the photo was rated as having “very good” standability or resistance to lodging. Also, the soil was not low in potassium, demonstrating that while selecting resistant varieties and maintaining potassium soil test levels are important to reducing lodging, they are not the entire solution.

The management practice that possibly contributed most to the lodging in the field in the photo was the high planting population. The field was planted at 170,000 seeds per acre in 22-inch rows. While this doesn’t sound excessive, it was too high for this highly productive field this year. The planting population can be safely reduced to 135,000 to 140,000 seeds per acre given the precision planting equipment used and the soil type in this field. This recommendation is based on 90 percent germination and 90 percent emergence. An important rule of thumb to remember when planting soybeans is to increase soybean planting populations on low productivity soils and decrease populations on highly productive soils. This provides the greatest economic return on your seed investment while reducing the potential for white mold and lodging to occur.

Identify the management practices that contributed to the lodging in your fields this year and use this information to reduce the potential for lodging to occur in future soybean crops. The next step is to understand and implement specific management practices that will reduce harvest losses and increase harvest efficiency in this year’s lodged soybean fields. The latest Michigan State University Extension recommendations for harvesting lodged soybeans are available online at “Recommendations for harvesting lodged soybeans.”

This article was produced by the SMaRT project (Soybean Management and Research Technology). The SMaRT project was developed to help Michigan producers increase soybean yields and farm profitability. The SMaRT project is a partnership between MSU Extension and the Michigan Soybean Checkoff program.

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