Our agronomist prefers planting soybeans 2 inches deep to encourage deeper nodulation. So far, we plant 1 inch deep. Are there risks in planting 2 inches deep?

 

The Indiana certified crop advisers panel answering this question includes Gene Flaningam, crops consultant, Vincennes; Carl Joern, field agronomist with Pioneer, northeast Indiana; and Greg Kneubuhler, agronomist, G&K Concepts Inc., Harlan.

 

Flaningam: There is always risk of variable seeding depth. Planting too deep can be detrimental if growing conditions are less than optimal. Soybean seeds only have limited reserves. If planted too deep, those reserves can be depleted before emergence. Planting too shallow can also cause issues with moisture availability and seedling survival. If you consider planting soybeans at 2 inches deep, seed quality must be good. You will also need favorable growing conditions.

 

Joern: The deeper a soybean is planted, the more effort it must exert to reach the surface. Under ideal conditions, soybeans can emerge when planted deeper than 2 inches. When soils crust, the last push of energy needed to break through might be spent prior to reaching the surface when planted too deep.

 

I prefer 1 to 1.5 inches deep. More importantly, plant soybeans into moisture. One may think that shallowing up planting will hasten emergence, but it introduces a more hazardous environment for the seed. The closer to the surface, the greater the swings in temperature and variability in soil moisture. By planting soybeans into moisture at an adequate depth, one ensures more uniform soil moisture and temperature conditions, giving the best shot for even emergence.

 

Kneubuhler: I prefer a depth of 1.5 inches. It generally provides the best uniformity when it comes to soil temperatures and soil moisture to establish the most uniform stand. Soybeans tend to nodulate at depth planted. Soil temperature is important to that process.

 

Planting deeper than 1.5 inches increases variability. This affects germination, nodulation and, ultimately, uniformity. Special circumstances like last spring’s dry conditions would change my decision to push planting depths beyond 1.5 inches.