What cover crop practice changes qualify for carbon credits?

The three cover crop practice changes are:

1. First-time cover crop adoption on a field 
2. Extending the duration of cover crop
3. Adding a legume species to a cover crop that does not currently feature a legume

Practice change: Introduce a cover crop into a field’s rotation for the first time that has a season length (planting to natural or induced termination) of more than 30 days. Note: This means planting a cover crop on the field for the first time, not adding another cover crop species.

Examples of qualifying scenarios:

1. A corn-soybean grower who has never planted a cover crop before plants a cover crop in late October after corn harvest and allows it to grow for 30 days or more before natural or induced termination 
2. A corn-soybean grower, who has historically planted cover crops after harvesting soybeans, but not after corn, now decides to apply the same cover crop blend after corn harvest as well.

Agronomic benefits: Planting a cover crop is an excellent way to prevent erosion, maintain soil microbial activity, and continue the accumulation of carbon outside of the cash crop season. A well-established cover crop with high biomass can help maximize soil protection. 

Recommendation: The longer a cover crop grows, the more benefit it will have on the field in terms of soil health and weed suppression. 

Practice change: Planting 14 or more days earlier than historical planting of a cover crop, or terminating 7 or more days later than historical. 

Examples of qualifying scenarios:

1. A grower who has traditionally planted a winter-killed species of cover crop now adds an additional species to the blend that will over-winter. As a result, they terminate the cover crop greater than 7 days later than they have historically. This practice qualifies, not because of the species added, but rather because of the additional season length gained by the overwintering of the blend prior to termination. 
2. A grower plants a cover crop one week after the cash crop harvest. The following year, the grower plants their cover crop three weeks prior to cash crop harvest (i.e., more than 14 days earlier than when the cover crop had been planted in previous seasons). 

Agronomic benefits: Increasing the duration of cover crops will reduce the fallow period in your field and increase the amount of time you are using the available sunlight to build healthier and more resilient soil. Plus, 7 – 10 days of more cover crop growth can be the difference of 6” – 18” of biomass, which is a key driver to store  more carbon in the soil. 

Recommendation: The longer you can keep a living root in the ground to convert sunlight and precipitation into plant biomass, the greater the impact on soil health and carbon sequestration. 

Note: Extending the duration of a cover crop is a great way to qualify for the program if you currently plant cover crops.

Practice change: Add a legume species to an existing cover crop blend that does not currently have a legume.  

Example of qualifying scenarios: 

1. A grower planted a cover crop mix consisting of oats and daikon radish. The following year, the grower adds crimson clover to the mix. 

Agronomic benefits: The primary benefits of increased cover crop diversity are increased plant photosynthetic capacity, as well as increased soil microbial diversity. Adding a legume specifically will also produce an N credit for the following cash crop.  

Recommendation: There are many options to consider when thinking about adding species to an existing cover crop mix. Thinking about the balance between plant groups (i.e., grasses, brassicas, broadleaves, legumes, etc.) is an important consideration as well as the preceding and subsequent cash crops to avoid a “green bridge” for pests. 

• Depending on what the grower is hoping to address with cover crops, keep in mind the carbon to nitrogen ratios (C:N), winter hardiness and even plant companionship (i.e., how well plant species grow together) are all important considerations.