Planting green

DOES IT WORK TO PLANT GREEN INTO COVER CROPS FOR CORN?

Planting corn directly into a living cover crop before it is killed by herbicide or tillage is not something that would have been considered 30 years ago. However, with advances in planter technology, herbicide options, and a greater awareness of cover crop benefits to soil health, more growers are doing it. For those looking over the fence at these systems, the key question is: does it work? To help provide an answer, I followed five Ontario corn fields during the 2023 season that were planted green into cover crop mixtures.

FIVE UNIQUE FIELDS

The fields were spread across four different counties: Brant, Bruce, Haldimand, and Niagara. Soil textures ranged from sandy loam to silty clay. Cover crop stands varied from sparse to very thick (e.g., Figure 1) and all were multi-mixes that included species such as hairy vetch, crimson clover, turnip, and cereal rye.

The study sites received no rainfall at all after May 20, 2023, for approximately three weeks, but then experienced 15-85 per cent above average rainfall for June, July, and August.

PLANT STANDS AND YIELDS

Average corn stand was 29,000 plants per acre, with emergence at 86 per cent of seeding rate across the five sites. The greatest challenges in corn stand establishment and uniformity were observed in the thickest cover crop (Figure 2) and on the clay soils. On the Haldimand site (a silty clay), the cover crop delayed emergence by 2.5 weeks due to soil moisture depletion, which highlighted the risk of planting green on soils that quickly go from too wet to too dry.

Despite stand challenges and slow early season growth, each field progressed well and average yield came out at 194 bushels per acre – 28 bushels per acre above county averages.

DOES PLANTING GREEN WORK?

Planting corn green into cover crop mixtures can work in Ontario. It does, however, require an advanced level of management, and can carry a higher level of risk.

Take the following steps to increase the likelihood of success:

• Target modest spring cover crop growth
• Modify planter to achieve adequate downforce and slot closure (Figure 3)
• Apply a higher-than-standard upfront nitrogen rate
• Match burndown herbicides and rates to control all cover crop species

Know your risk tolerance and consider which goals the system may help you achieve. Find other farmers to learn from and begin by experimenting on a small acreage.

To learn more, visit www.fieldcropnews.com or watch Real Agriculture’s Corn School. •