Types of Fertilizer for Soybeans

Lime

• Lime soil amendments are often added to control soybean soil pH levels. According to the University of Nebraska at Lincoln Cooperative Extension, soybeans require a pH of approximately 5.5 to 7.0 to reap the benefits of the Bradyrhizobium japonicum bacteria, which increases nitrogen availability to plant roots. Usually about four to seven years pass before you see the effects of lime application, although soil pH levels should increase within 6 to 18 months of application.

Zinc

• Depending on the crop region, some soybean crops may suffer from zinc deficiency. For example, zinc deficiencies have been found in soybean crops in some areas of North Dakota. Zinc problems are especially common in sandy soils. Deficiencies result in discolored, small leaves that may turn bronze or become spotted. Zinc deficiencies are likely to occur in crop locations that have had previous problems and can be easily corrected by adequate fertilization.

Iron

• Iron fertilizers are often required for soybean crops. Iron deficiency is particularly common in soils with high levels of calcium carbonate and results in yellowing of young plant leaves. In Nebraska, where soybeans are the second most common crop after corn, iron fertilizers are often required in soils with high pH levels. Over-watered crops are also very likely to suffer from iron deficiency. Unfortunately, many fertilizers to treat iron deficiency are ineffective, according to the North Dakota State University Extension. Select soybean varieties for high-lime soils to avoid iron deficiency.