There are many opportunities to include cover crops in the rotation. The goal is to keep the soil covered with at least 30% crop, cover crop or residue, 100% of the time. A second goal is to have living roots in the soil as much as possible. Research at University of Guelph, Ridgetown Campus has shown that planting a cover crop provides a benefit, even if the growth is limited. So consider the these options and find a way to reap the benefits of cover crops.
Interseeding into Corn
There is a fair bit of interest in interseeding cover crops into standing corn. Different seeding times have been tried - from the 5- to 6 leaf stage of corn, to the tassel stage, to when the canopy begins to open up late summer or early fall. The most success in Ontario has been with seeding annual ryegrass and/or a clover at the 5 to 6 leaf stage of corn. Some growers have developed equipment to plant the cover crop or to move some soil after broadcasting the seed. Most broadcast the seed. Ryegrass seeding rates are generally 15 to 25 lbs/ acre. A rule of thumb for broadcasting cover crop seed is to add 20% to the drilled in rate.
It is important to think about the herbicide program when planning to interseed into corn. Table 1 lists herbicides that can reduce the success of the cover crop.
Table 1: Potential for injury to ryegrass and clover cover crop interseeded in corn.
Herbicide | Annual ryegrass | Clover |
Converge XT | Safe | injured |
Callisto | Some injury - some stand reduction | injured ** |
Engarde | Some injury - some stand reduction | injured ** |
Integrity - Set up rate | Safe | Not injured |
Integrity - full rate | Injury - stand reduction | Some injury |
Primextra | Injury - stand reduction | Some injury |
Lumax | Injury - stand reduction ** | injured ** |
Treflan/Prowl | Injury - some stand reduction * | Some injury |
Focus | Injury - stand reduction ** | Slightly injured |
Frontier Marksman | Injury - some stand reduction * | Some injury |
(*) Indicates severity of damage, more * = more damage
Source: Dr. Darren Robinson, University of Guelph, Ridgetown Campus, project funded under GF2
Some growers have interseeded cereal rye at 60 lbs/ac into corn as the crop begins to mature or even after harvest. They have achieved enough growth late fall and early spring to provide some benefit.
Cover Crops Following Cereals and Late Summer Harvested Crops
"Cover Crops Following Cereals and Late Summer Harvested Crops" has more information on cover crop options in this time frame.
Cover Crop Options in Soybeans
When winter wheat as a crop is not an option after soybeans, consider seeding a winter cereal as a cover crop. The most common option is rye, but any winter cereal will do such as wheat, barley or triticale. Broadcast 60 lbs/ac at 10% leaf drop, or drill it in immediately following harvest.
Source: OMAFRA