A simple recipe for double crop soybean success during the hot, dry summer might be “seed to moisture and pray for rain.”
But it’s not that simple says Syngenta agronomist Eric Richter, one of Canada’s leading experts on the double crop system. In this episode of Soybean School, Richter joins RealAgriculture resident agronomist Peter Johnson to discuss the five key factors that contribute to double crop soybean success.
At the end of the day, it comes down to moisture.
“If the soil is bone dry and the forecast says no rain for three weeks – don’t do it. You need good moisture to make this work,” says Richter.
Both he and Johnson agree that deeper planting is a good option to ensure the seed has access to moisture.
“Seeding at three to four inches is something you wouldn’t dream of doing in the spring but there’s something different about the double crop,” says Richter. “The warm July soil temperatures really have the ability to extend the cotyledon… don’t be afraid to go to moisture. Go deep.”
Another key factor to consider is planting date. July 1 is the optimum planting date, says Richter.
“Every day (you plant) after July 1 equals a bushel per acre. That’s the bottom line. You lose a bushel a day from July 1 to July 15.” After that date, planting is no longer recommended.
Selecting the right soybean maturity is also critical.
“I think maturity is the most important criteria to make the system successful,” notes Richter. He recommends growers ‘downshift’ the maturity of their varieties through the July 1-15 period. The objective is to shorten maturity as the planting window closes.
On July 1, growers should shorten varieties by three-quarters of a maturity group. If they are planting July 15, they should shorten by 1.5 maturity groups.
Richter also explains that there is a strong relationship between planting date and population. He recommends starting with a population of 225,000 to 250,000 seeds per acre on July 1. “Then we jack it up to 275,000, even possibly 300,000. I know that’s a lot, but our goal here is to have canopy closure by R1 – first flower.”
Row width also plays a significant role in success. Richter recommends 7.5-inch rows seeded with a drill or air seeder. “There are a few at 15 inches, but those growers struggle to break 35 bushels,” says Richter.