Managing cover crops in a dry Ontario spring

OMAFRA’s Jake Munroe and Anne Verhallen.

Cover crops deliver significant soil health and ground cover benefits, but they can often cause spring headaches when growers fail to kill them off in advance of corn and soybean planting.

In this video report from Ontario Diagnostic Days 2021, Ontario Ministry of Agriculture, Food and Rural Affairs soil management specialists Anne Verhallen and Jake Munroe share tips for cover crop management as well as some lessons they learned during dry spring conditions.

In some cases during 2021, growers seeded into dry ground because aggressive, still-growing cover crops gobbled up soil moisture. Generally, corn and soybeans were planted in good time; however, moisture was depleted if the cover crop was not terminated in a timely fashion at planting. “In some fields last spring, if it were not for a timely rain, the crop would not have achieved an adequate stand for lack of moisture,” notes Verhallen. (Story continues after the video.)

In the report, Verhallen shares cover crop management practices that will help growers make their soils more resilient and provide an insurance policy to mitigate against dry spring conditions.

One consideration growers need to think about is their soil type. “How much residue can you handle come spring and what should you do to ensure you can get in there in a timely manner to burn down the crop,” asks Verhallen. She notes it’s important to select the right seeding rate depending on your goals and how you intend to manage the crop. “If you are not grazing it or planning to take it off as forage you can back off on the seeding rate.”

Verhallen notes that it’s important for growers to make choices depending on whether they intend to take out the cover crop in the fall with herbicide or light tillage. Spraying the crop out late in the fall will allow roots to remain intact and help with erosion control but growers won’t have to wrestle with a big, growthy cover crop come spring, she adds.

Munroe and Verhallen also explore the growing popularity of rye as a cover crop. “It’s fairly inexpensive, quite resilient and can be seeded late in the season…but it also creates some challenges in that it’s an over-winter species,” says Munroe.

Verhallen adds that many growers try to fit rye in after corn and soybean harvest: “It will grow very quickly under warm, moist conditions in the spring so you have to be on it.” She notes there are several different strategies for managing rye. The standard recommendation, especially in advance of corn, is to control it with herbicides at least two weeks before corn planting. This reduces residue and competition for nutrients. When it comes to planting green, the crop needs to be sprayed immediately before or after planting.

Strip tilling into a rye cover crop is another management option and the tillage system is very effective in moving rye residue away from the corn plant. Growers also need to consider rye planting rate, says Verhallen. Planting 40 to 50 pounds per acre or less will reduce stand thickness, making it more manageable in either a dry or wet spring.

Click here to view the complete 2021 Ontario Diagnostic Days series.