Relay-intercropping and double-cropping systems in Iowa have potential benefits but entail much risk, according to Iowa State University studies. 

Relay intercropping is a multiple cropping system where a second crop is planted into a standing first crop. It’s a twist on double cropping, where a second crop is planted following harvest of the first one in the same year.

In 2018 and 2019, ISU researchers evaluated relay intercropping and double cropping near Kalona and Ames.

Researchers planted cereal rye at the Kalona site immediately after corn harvest. Following harvest of cereal rye, researchers double-cropped soybeans.

In 2018, yields were 46.1 bushels per acre for cereal rye and 23.2 bushels per acre for double-cropped soybeans. In 2019, the cereal rye yield averaged 30 bushels per acre. Soybeans did not reach maturity and were unharvestable.

Researchers evaluated four treatments near Ames. They included:

Wheat yields averaged 57.2 and 30.1 bushels per acre in 2018 and 2019, respectively. Lower 2019 yields were attributed to cooler, wetter spring conditions.

Related:7 tips for better relay crops

Soybean yields averaged 16.3 and 33 bushels per acre in 2018 and 2019, respectively. Wet fall conditions in 2018 delayed harvest and caused pod shattering. In 2019, the higher soybean yields were attributed to the soybean and winter wheat system, as the lowest yield occurred in the double-crop soybean system.

Consider the risks

Soybeans with winter wheat — or other small grains — can fit both relay intercropping and double cropping, says Mark Licht, ISU Extension agronomist. It’s a way to glean two crops from one field in one year.

These alternative cropping systems also can reduce risk of nitrogen and phosphorus losses, he adds.

However, double cropping carries high risk due to lower soybean yield potential spurred by early- to mid-July planting dates and a stronger chance of frost damage.

Relay intercropping reduces some of this risk, but it has its perils, Licht says. They entail:

Related:How to farm entire field — even between corn rows