RESEARCH REPORT: Corn Leaf Architecture for Interseeded Cover Crops
In Iowa, cover crops are typically either aerially seeded into standing corn around the time of physiological maturity in late summer or drilled immediately following corn harvest in the fall. However, the earlier one can seed a cover crop, the more potential for growth and biomass production. An earlier seeding date also opens up the opportunity for more diverse cover crops like brassicas and legumes that need more time and heat units to grow than common cover crops like cereal rye.
Farmer researchers Jack Boyer and Jeremy Gustafson interseeded cover crops (cowpeas, annual ryegrass, rapeseed) into corn at the V4 stage in June. Corn hybrids chosen exhibited vertical and horizontal leaf orientations to test whether more light penetrating the corn canopy would encourage successful cover crop establishment and growth.
Read the full report here: Corn Leaf Architecture for Interseeded Cover Crops.
How Was the Trial Conducted?
- Corn planting date (both hybrids): Boyer = Apr. 25; Gustafson = May 5
- Cover crop mix interseeding date: Boyer = June 14; Gustafson = June 16
- Cover crop mix seeding rates: Cowpeas (60 lb/ac); annual ryegrass (22 lb/ac); rapeseed (7 lb/ac)
- Corn harvest date (both hybrids): Boyer = Nov. 4; Gustafson = Oct. 25
Aboveground biomass of the cover crop mixes was not sampled but photographic evidence shows that cover crops persisted beneath the corn canopy into early fall at both farms.
Corn yields at Boyer’s were affected by the hybrid (horizontal leaf architecture vs. vertical leaf architecture) and the interseeding. See figure below.
At Jeremy Gustafson’s, corn yields were not affected by hybrid or planting population. All strips were interseeded. See figure below.
“The seed germinated well,” Gustafson said, seeing mostly cowpeas by mid-September. “Not much made it into fall, though. Leaf architecture didn’t seem to matter and lack of rain really played havoc with this trial.”
“This technique requires more testing before wide spread adoption,” Boyer said. “I need to understand what caused the yield hit. The cover crop species I interseeded worked with both corn varieties, so I will probably try another interseeding with just one variety.”
For more details on this trial, read the full report: Corn Leaf Architecture for Interseeded Cover Crops.
This project was supported by the Walton Family Foundation.