I introduced the weekly series in September and have since wrote about boron, chloride, cobalt, copper, iron, manganese, molybdenum, nickel and zinc. I covered how each micronutrient is essential to soybeans, known deficiencies or toxicities in the region, factors of micronutrient availability in soil, soil and plant tissue testing, and fertilizer recommendations. Interest and concern about micronutrient needs of soybeans is common due to higher yields than in previous decades and the increased availability of micronutrient fertilizers in both liquid and dry formulations. However, micronutrient issues are regional in nature. For example, boron deficiency in soybeans following rice in Arkansas is not uncommon or copper deficiency in small grains on poorly drained peat and muck soils in the upper Midwest. In Nebraska, we see differences between crops, regions, and soils when it comes to micronutrients like iron deficiency chlorosis in soybeans. So what micronutrients are of the greatest concern in southeast Nebraska for soybean producers?
I encourage to you go back and reread the articles on each micronutrient as you may have questions not addressed in this summary. As a wrap up, I decided to broke the nine micronutrients into three groups of concern for southeast Nebraska: Maybe (iron, zinc, and chloride), very unlikely (boron and molybdenum), and extremely unlikely (cobalt, copper, manganese, and nickel). For this last group of “extremely unlikely”, I would challenge you to address many other known yield-limiting factors (SCN, SDS, Palmer, soil pH, etc.) for soybean production in your operation first. I encourage you to do two things for the “unlikely” group including boron and molybdenum. For molybdenum, get your low soil pH raised to 6.0 to 6.5. Implementing a sound soil sampling and lime application plan is critical for soybean production regardless of a molybdenum concern. For boron, soil test analysis is not very reliable, so utilize plant tissue analysis as a quality control tool this next growing season. Don’t apply boron unless plant tissue analysis last year suggests you have a potential issue, then conduct on-farm research to validate that potential issue.
The “maybe” group (iron, zinc, and chloride) are micronutrients with documented or potential issues. Iron and zinc deficiency are likely the most common micronutrient deficiencies in southeast Nebraska. Iron deficiency chlorosis is best managed through cover crops, variety selection, and in-furrow EDDHA chelated iron fertilizer (e.g. SoyGreen) while leveraging Ag technology to target hot spots within fields. Zinc deficiency more likely occurs on calcareous soils, where topsoil was moved or lost, or in very sandy soils. Zinc deficiency is effectively managed with good soil sampling, DPTA soil test analysis and unbiased zinc fertilizer recommendation. Chloride toxicity in soybeans in saline soils or through using irrigation water high in chloride are possible, but uncommon. If you have not analyzed your irrigation water quality, I encourage you to take a sample next summer during the irrigation season.
I hoped you enjoyed this series on managing micronutrients for soybean production in southeast Nebraska and I would love to hear your feedback, so email me (), leave a comment on my website, or give me a call (821-1722). As a reminder, you can share or read this news column online through my local website for Saline, Jefferson, and Gage counties at croptechcafe.org. Know your crop, know your tech, know your bottom line.
