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From V4 to V6: Why Nodal Root Development Matters - Crop Cast Episode 38

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Another agronomy deep-dive brought to you by Crop Cast. In Episode 38, host Sean Nettleton, along with Jason Schley and Jaren Schley takes us beyond the basics and into the underground world of roots—specifically, the nodal roots that form during the V4 to V6 stages of corn development. This period marks a major physiological transition in the plant’s life, and the insights shared in this episode are essential listening for anyone who’s serious about maximizing yield potential.

Let’s unpack the episode and dig deeper (pun intended) into why nodal root development during this stage is such a game-changer.

What Are Nodal Roots, and Why Do They Matter So Much?

By the V4 growth stage, corn is no longer relying on the seed for energy. That early taproot system is on its way out, and the plant is now depending heavily on the development of nodal roots, those secondary roots that form at the crown of the plant and expand horizontally and vertically through the soil.

Jaren makes this simple but crucial point: “The more emphasis we put into root growth, the better opportunity we have.” These nodal roots aren’t just there to anchor the plant. They’re the main highway for nutrient uptake, water absorption, and long-term plant stability. Weak or underdeveloped nodal roots limit a plant’s ability to access nutrients, fend off stress, and support the surge of vegetative and reproductive growth that follows.

 You can think of them as the plant’s circulatory system, just like veins and arteries carry nutrients and oxygen through the body, nodal roots are the essential channels that deliver water, minerals, and energy to every growing part of the plant. If this system is weak or underdeveloped, the plant can’t function at full capacity, no matter how much you feed it.

The Offense-Defense Agronomy Dilemma

During V4 to V6, the plant is in a sensitive transition phase and what we do now can dramatically affect outcomes later. Jason and Jaren tackle the age-old agronomy balancing act: when to play offense (growth promotion) and when to play defense (stress management).

Jason warns that “If we don't create sugar at this point, we are not gonna have this transition.” That’s because sugar, produced via photosynthesis and powered by nutrient uptake, is essential for driving root growth and preparing the plant for the reproductive stages ahead.

At this phase, the goal is to support both above- and below-ground development. That means avoiding stressors like herbicide injury and prioritizing well-timed, nutrient-dense applications that support energy production and root establishment. Skip this step, and you may find your plants struggling to maintain momentum when they need it most.

 

Feeding the Foundation: Nutritional Focus for Root Health

You can’t grow what you don’t feed and nodal root development is hungry work. The episode highlights the importance of phosphorus and zinc, two key players in early growth and energy transfer. But it doesn’t stop there.

Cation exchange matters, too. Calcium, potassium, and magnesium help transport nutrients across root membranes, enabling more efficient uptake and utilization. The more effectively we support this process, the more energy the plant has to keep building its root system and preparing for reproductive success.

As Jason points out, “The higher the nutrition, the more sugars... and ultimately, the bigger the nutrient release.” It’s not just about putting nutrients in the soil but also about making sure the plant is equipped to take them in and use them well.

 

Root Lessons for Soybeans, Too

While corn takes center stage in the nodal root conversation, Jaren also touches on soybeans and the importance of nodulation. In soybeans, it’s not nodal roots but rather root nodules, those tiny nitrogen factories that determine early-season success.

“The earlier you start and the harder you push, the better the total potential of yield becomes,” he says, underscoring how early nodulation sets the tone for bloom formation and pod fill. Like nodal root development in corn, early vigor in soybeans drives reproductive potential.

 

In Agronomy, Timing Is Everything

Perhaps the most quotable takeaway from the episode comes when Jason says, “Agronomy is great, but logistics trumps agronomics.” In other words, knowing what to do isn’t enough—you have to be able to do it at the right time, in the right place, with the right tools.

That’s where decision-support tools like FertiCast come in. By layering crop stage data with weather, nutrient needs, and application logistics, growers can make smarter, more precise moves to support root development and long-term plant health.
 


Final Thoughts: Root Now, Reap Later

Episode 38 is a powerful reminder that what happens below the surface often matters most. From the V4 to V6 stages, your corn is making a big leap—from seedling to self-sufficient engine of growth. If we support that transition with the right nutrition, stress management, and application timing, we set the stage for success.

Want a stronger stand, higher nutrient efficiency, and better reproductive output? Start with your roots—because a thriving crop begins underground.

Listen to Episode 38