No beans about it: Planting too deep decreases yield potential
When it comes to soybeans, planting deeper is not always better. In fact, more than 50 percent of Indiana farmers are planting outside of the recommended range, said a Purdue University expert.
"According to the 2005-2006 Plant Management Network (PMN) soybean survey, only 46 percent of Indiana soybean growers plant in the recommended seeding depth, which is three-fourths of an inch to an inch and a half deep," said Shawn Conley, Purdue Extension soybean specialist. "About 42 percent of growers are planting deeper than an inch and a half."
Because many farmers are planting soybeans earlier than they used to, planting the seeds too deep can prove detrimental to yields.
"If growers are planting soybeans deeper, plus moving the planting date earlier, that seed is sitting in the ground in cold, wet soils and that can lead to issues related to stand establishment," Conley said.
In addition to cold, wet soil exposure, seeds planted too deeply take longer to emerge and are more susceptible to pathogens, Conley said.
"As we shift to an earlier planting date, continuing to plant that seed two inches or deeper takes anywhere from 18-24 days for emergence," Conley said. "By planting deep and planting early, we're allowing more time for that soybean plant, as it emerges, to be exposed to different pathogens and different issues that may further hinder emergence.
"As growers shift to that earlier planting date, we need to go out and make sure that our drill or planter unit is calibrated and set correctly based on whatever tillage regime we use, whether no-till or conventional-till, and we're getting uniform depth at three-quarters to an inch and a half deep."
While paying attention to seeding depth is one of the simplest ways to improve stand establishment and yield potential, there are other preparations farmers can be making for the upcoming planting season, Conley said.
"Growers need to make sure that as they go through their equipment, the bearings are in correct working order, everything is greased and everything is in tip-top shape so that once they are able to plant, they donít have any mechanical problems," Conley said.
And because Indiana has less-than-predictable spring weather, Conley said farmers need to make sure equipment is working properly so they can take advantage of nice weather early in the planting season, which can ultimately maximize yields.
By paying attention to seeding depth and taking the time to prepare for the planting season, Conley said growers can improve stand establishment, achieve a more uniform stand emergence and maximize yield potential.
For more information about soybean practices in Indiana, the PMN survey or to see the results, visit http://www.plantmanagementnetwork.org/sub/cm/research/2007/practices/ .