Illinois producers spend a lot of time developing a strong corn nitrogen program and implementing it throughout the growing season. We know that nitrogen is very important to a growing corn crop, but it’s just as important to a soybean plant. However, realistically, how much time is spent managing soybean’s nitrogen needs? There’s still an ongoing debate regarding how much nitrogen a corn plant needs, but it will likely fall between 0.9 to 1.2 units of nitrogen per bushel produced. However, a soybean plant can utilize upwards of 4.5 to 5.0 units of nitrogen per bushel produced. With this increased demand compared to corn, how come more focus isn’t on managing nitrogen for soybeans?
Since a soybean plant is a legume, it can create a relationship between its root system and the bacteria living in the soil. This relationship results in nodules on the root system that when active (inside turns red), will supply plant-available nitrogen to the crop.
The nodules’ supply is directly related to the quantity and quality of active population living in the soil. The nodulation process will start around the V2-V3 growth stage. The quantity and quality of the nodulation can be impacted by crop rotation, drainage, tillage, pH, etc. Since nitrogen is important to soybean yields, it’s important to evaluate nodulation throughout the season: How many nodules are there? Where are they located on the root? What color is the inside? If low numbers are found, it’s time to start asking questions and looking for possible solutions.
There are currently several seed treatment options on the market that can provide supplementary support to boost the population in and around the root zone. However, not all products are created equal and one must ask the right questions to select the right product. For example: some products can be used as a dry powder in the seed box, and others are added as a seed coat. All these products are providing a different longevity of the bacteria that is being treated—bottom line, do your homework.
Regardless of your seed treatment selection, rotation, tillage and drainage system, it’s always important to stop and dig up soybean roots throughout the season to evaluate nodulation. Even if it’s later in the season and the nodules are no longer active, one can still find the growth on the roots for evaluation.
Steinacher is an ISA CCA Soy Envoy alum and currently supports ISA on agronomic content as well as serving as an Illinois CCA board member. He was recently awarded the 2020 IL CCA of the Year & the 2021 International CCA of the Year. He has over 15 years agronomic experience, currently working with AgriGold and GROWMARK previously. Steinacher has an associate degree from Lincoln Land Community College, a B.S. in agronomy and business from Western Illinois University and a master’s degree in crop science from the University of Illinois at Urbana-Champaign.
The Illinois Soybean Association (ISA) checkoff and membership programs represent more than 43,000 soybean farmers in Illinois. The checkoff funds market development and utilization efforts while the membership program supports the government relations interests of Illinois soybean farmers at the local, state, and national level, through the Illinois Soybean Growers (ISG). ISA upholds the interests of Illinois soybean producers through promotion, advocacy, and education with the vision of becoming a market leader in sustainable soybean production and profitability.