With corn acres expected to be at record are near-record highs in the Southeast this spring, many growers are fine-tuning their production practices — tweaking things such as plant populations and planting dates — to guarantee the greatest return on their investment.

A study conducted by Auburn University researchers in 2011 and 2012 at the Gulf Coast Research Center in Fairhope, Ala., evaluated the impact of plant population on yield, and the impact of the interaction between plant populations and planting dates on corn yields in non-irrigated conditions.

It’s well known that plant population can positively or negatively affect corn yield, but yield potential also can be influenced by planting date, which is strongly linked to the at-planting and in-season weather and climatic conditions.

“When considering management changes, farmers need to keep in mind that the optimum plant population will not only vary between regions of the state, but from season to season, and from field to field on the same farm,” according to the research report.

Currently, there is a big push to increase plant population in order to increase production, states the report. However, this change is typically recommended under non‐limiting conditions, such as those with an ample water supply and adequate fertilization.

Corn genetics have evolved to the point to where farmers can delay planting to take advantage of favorable environmental conditions, while maintaining a good insect protection and water-use package.

Researchers say that a combination of the currently available corn hybrids along with a growing knowledge of climate variabilities within regions allow them to investigate how plant populations and/or planting dates should be modified in order to increase production and profitability and reduce potential production risks.

The Fairhope, Ala., research — conducted on Malbis fine sandy loam soils — consisted of four different plant populations of 18,000, 22,000, 26,000, and 30,000 seeds per acre planted at two different times during the growing season: mid‐March (standard date by farmers in the area) and three weeks later.

The corn hybrid planted was Pioneer 31P42 with a relative maturity of 119 days. Experimental plots were four rows wide by 30 feet long with 38-inch row spacing. Plots were fertilized with 150 pounds of urea ammonium nitrate. Yield data was recorded after harvesting the middle two rows of each plot.

Regardless of the plant population and planting dates chosen for the study, corn yield in the 2011 season was lower than in the 2012 season. The year‐to‐year yield changes could be associated with differences in the climatic conditions.

When comparing 2011 and 2012 monthly precipitation and maximum temperature deviations with respect to historic values (1970‐2000), the main differences were observed from May to July which corresponds to the months of flowering and grain filling.