Digging into corn and soybean growth

By Greg LaBarge, Ohio State University Extension

If the growth of corn and soybeans is not what you were expecting, look below the soil surface for answers. Our 2026 growing season has given us moisture and temperature conditions that have made achieving even emergence and maintaining the emerged stand challenging. Stand loss due to drowning out, plant freezing, and variable soil moisture conditions at planting have required more trips across the field than we would have liked. Lessons to apply for future years can be learned by spending some time evaluating the stands we end up with. The best tools for this evaluation are a shovel and knowledge of what plant roots look like under various conditions.

Evaluating uneven corn and soybean roots requires carefully digging up representative seedlings (rather than pulling them) to expose the full root architecture. The root structure will typically reveal specific physical or chemical limitations. Understanding root orientation and soil health helps distinguish between planter issues, compaction, and early-season diseases.

1. Dig, Don’t Pull. Always dig up your target plants using a shovel. Pulling the plant will break off the delicate seminal roots and fine root hairs, masking critical symptoms.

2. Identifying Specific Root Symptoms. The shape and development of the roots point to exactly what is happening in the soil.

• “Tomahawk” Roots (Corn): If roots appear flattened on two sides and are growing strictly in a line, you are dealing with sidewall compaction. This happens when planting into soil that is too wet, causing the planter’s double-disc openers to smear the trench.

• Horizontal “J” or “L” Roots: If the taproot takes a sharp 90-degree turn, the seed was planted into a compacted soil layer, commonly known as a hardpan.

• Rotten or Brown Roots: Discolored, decaying, or pruned-looking roots are indicators of seedling blights or damping-off. These issues often occur if the soil is persistently cool and saturated, or if fungicidal seed treatments have worn off.

• Brittle, Pruned, or Off-Colored Roots: If roots look “burnt” (brown tips) and plants are wilting, you may be experiencing anhydrous ammonia injury (if fertilizer was applied too close to the seed trench) or fertilizer salt burn.

• Stubby or Swollen Roots: This suggests herbicide injury (e.g., carryover from the previous season or pre-emerge chemicals).

3. Evaluating Gaps and Missing Plants. Moisture and temperature conditions at emergence or planter performance may explain the gaps. Even at our current growth stages, remnants of ungerminated seed can remain in the row to help determine whether planter performance or seed germination was the issue behind missing plants.

Corn: Uneven height within a row (plants 2-3 leaf stages apart) is primarily driven by inconsistent soil moisture and temperature where the seeds were placed. Kernal absorbs 30% of its weight in water to germinate. Soil temperatures are another variable to emergence, with 50 degrees or greater needed for germination. Poor seed-to-soil contact can occur when wet soils are worked and then dry out.

Soybeans: Uneven soybean emergence occurs under conditions similar to those described for corn. Soybeans must absorb roughly 50% of their weight in water to germinate. Soybeans are remarkably forgiving of emergence delays. Populations of 50,000 plants per acre can have respectable yields depending on plant distribution and varietal branching.

A careful look beneath the soil surface often reveals the real story behind uneven emergence and disappointing early‑season growth. By taking the time to dig plants, study root architecture, and connect visible symptoms to field conditions, growers can separate weather‑driven setbacks from preventable management issues. The more we understand these early‑season signals, the better equipped we are to make informed adjustments—whether in tillage, planting timing, seed placement, or input decisions—to protect stand establishment in future years. In a season defined by variability, the shovel remains one of the most valuable diagnostic tools on the farm.