Poor Corn Germination and Root Development (06/10/21)
The drought conditions have resulted in many fields experiencing poor corn germination, root development and early growth. There is some concern whether a primary reason for these symptoms is seed-placed starter fertilizer, or fertilizer rate in general. The primary reason for the symptoms is the drought, and any other factor that increased the severity of the condition cascaded from the dry soil. If seed-placed starter fertilizer rate was about 3 gallon or 10-34-0 or any other P-based starter, then the risk to the corn was minimal. As rate increased above this, the higher rate may have increased the severity, but without a check area with no fertilizer, it is impossible to confirm this. In my experience in the 1988 drought in central Illinois (experienced by North Dakota farmers also), a 6 gallon per acre 10-34-0 rate used by a farmer who had used the rate for years successfully resulted in stand loss, whereas farmers using a 3 gallon per acre rate experienced no reduction in stand. However, due to the drought, it’s effect on yield was negligible because the yield was so reduced by the continuous 100-degree weather during pollination and continued drought that corn yields with or without stand loss were similarly poor.
The poor root growth and the ‘burned off’ appearance of roots that have emerged in dry soil is due to both the heat of the soil and particularly the extreme soil dryness. Roots will not grow into dry soil. A common thought is that ‘roots grow to moisture’, but this is untrue. Roots grow through moisture to get to more moisture, but any very dry layer of soil in between the root and deeper soil moisture restricts the root growth to the dry layer. Another factor to consider is the soil salt (EC value). Corn is susceptible to higher soil salts, and an EC greater than 2 would cause germination problems, early growth reduction and seedling death. An EC analysis of the soil from the surface to the depth of the roots would be very useful in finding the secondary cause of the poor corn growth/germination issue.
Extension Soil Specialist