Researchers Nudge Corn Planting Date

US - Getting corn in the ground when soil temperatures are at or nearest 50 degrees Fahrenheit is fairly common knowledge in the Corn Belt.

9 April 2010

2 minute read

North America

But, the results of a recent study from a team of Iowa State University (ISU) Extension agronomists shows the ideal planting windows have changed a bit in that state in recent years. The new data's based on three years at seven field locations each year (2006, 2007 and 2008).

According to Agriculture Online, the study's results give date ranges based on maximum yield potential resulting from a range of soil temperatures, centering around the 50-degree mark.

"Corn will not germinate below a soil temperature of 50 degrees Fahrenheit, although seeds absorb water irrespective of temperature. Therefore, growers should plant when the soils are at or quickly approaching 50 to avoid seed rot, poor emergence and/or poor stand establishment," according to ISU agronomists and study leaders Roger Elmore and Lori Abendroth.

"Although planting too early can cause negative repercussions, in general, planting significantly after the recommended window has greater risk and potential loss for the grower."

The new research shows three distinct zones for Iowa, each with slightly different optimal planting windows. In the northeast third of the state, the study shows farmers have the narrowest timeframe for getting their crop in the ground. That's because of the tighter transition between seasonal weather patterns, the argonomists say.

"Grain yields begin to drop off more significantly here than the rest of the state if plantings are too late. We recommend planting between 12 April and 2 May (95-100 per cent yield window) or between 12and 30 April (98-100 per cent yield window).

"The dataset is limited for plantings before April 12 in this region, which limits our ability to make recommendations prior to this date," according to Elmore and Abendroth.

In the northwestern and central part of Iowa, planting date has historically had a lesser effect on yields, therefore farmers have a wider window.

Planting between 15 April and 18 May will net farmers a yield potential between 95 per cent and 100 per cent, Elmore and Abendroth say.

In the southern third of the state, temperature is even a smaller factor, leaving the planting window even wider, from 11 April to 13 May.

"The yield response in this part of the state is presumably related more closely to rainfall patterns and soil moisture than the length of the growing season since this typically is not a limitation as it is in the northern part of the state," according to the ISU agronomists.