Corn planters are running earlier than normal in parts of South Dakota due to the dry weather conditions which have persisted since fall.

Although South Dakota's spring planting window for corn generally runs from late April to mid-June - with 10 percent of corn in the ground by May 10 - mid-April's weather conditions suggest that corn planting may be able to proceed significantly ahead of normal in 2015, explained Dennis Todey, SDSU Extension Climate Specialist & South Dakota State Climatologist.

When planting into dryer conditions requires some additional considerations, explained Jonathan Kleinjan, SDSU Extension Crop Production Extension Associate

"Based on current dry soil conditions, it may be necessary to increase planting depth," Kleinjan said. "The standard planting depth of 1.5-inches may be too shallow in some fields this year."

Ideal seeding depth, Kleinjan said should be based on soil conditions and the near-term or 10-day weather outlook.  "When the seedbed is dry or is likely to become dry, planting depth should be increased to 2-3 inches if that is where there is uniform soil moisture," Kleinjan said. "Corn plants are easily capable of emerging from those depths and the risks associated with deeper planting are less than the risks of planting in dry soil with little to no precipitation in the forecast."

Kleinjan does not recommend planting corn deeper than 3 inches. "Moisture conditions, and thus ideal planting depth, may vary throughout the season and even throughout each field," Kleinjan said. "It is important to thoroughly check the conditions in each field prior to planting."

Weather may slow down emergence

Current weather forecasts suggest that the week of April 19, 2015 may be cooler than normal, which may affect soil temperatures, said Todey. "Because corn germination is a result of adequate moisture and temperature conditions, it is recommended that corn should not be planted until morning soil temperatures at a depth of 2 inches are at least 50 degrees Fahrenheit," Todey said. 

Kleinjan explained further that corn seeds will absorb water in temperatures below 50 degrees Fahrenheit, but they will not begin root or shoot growth; potentially leading to seed rot and poor emergence. "Corn hybrids with increased cold tolerance and fungicide seed treatments can help plant survival when planting at temperatures below 50 degrees Fahrenheit," Kleinjan said.

He recommended farmers consult with their local agronomist regarding corn hybrid selection and seed treatment decisions when contemplating early corn planting. 

Early germination considerations

Early planting potentially leads to early germination and plant growth.  The growing point of a corn plant emerges at the V6 growth stage after about 475 growing degree days (GDDs).  "Most research suggests that corn damaged by frost prior to the V6 growth stage will retain nearly 100 percent of yield potential," Kleinjan said.

He added that corn plants at the V9-V12 stage, damaged by a late season frost should recover but can have delayed maturity, reduced plant height, and yield reductions of up to 50 percent.

Producers can use the following online tool to predict corn growth stages, accumulated GDDs and spring or fall frost risks for any county in the U.S. Corn Belt. 

"The probability of accumulating enough GDDs for corn to reach the V6 growth stage, and thus be susceptible to significant frost damage, prior to the latest last potential freeze date is very small," Todey said. "This has only occurred once or twice in the last 35 years therefore, this should not be a concern in corn producing areas of the state."