Cover crops for carbon farming: what you need to know
Thursday, February 24, 2022
Agriculture is providing the world’s food, energy, and resources. Different land management strategies such as cover crops maximise farming capacity, providing soil, agronomic, and economic benefits to farmers.
When implemented right, cover cropping has the potential to help mitigate climate change as a recommended practice for carbon farming.
In this article, understand the role cover crops can play in your farm and how you can benefit when planning is done correctly.
Running a sustainable farm with cover crops
What are cover crops?
Cover crops protect the soil from erosion and improve nutrient conditions. These yields are different from the primary cash crop. They are grown precisely to help keep the soil intact which would otherwise be bare against winds, rains and water, and even tillage.
Cover crops can be classified into three categories, each utilising certain crops to protect and enhance the soil.
Cover crops: Reduces surface disturbance helping prevent erosion
Catch crops: Sown to capture nutrients to build soil fertility and prevent nutrient leaching
Green manure crops: Plants that are turned into the soil to maintain soil organic matter
Apart from knowing which crops to use, the timing when to sow and terminate crops also matters. For example, catch crops can be best introduced between the spring and fall harvests to keep nutrients available for the next growing season.
Cover crop benefits
Cover crops help improve soil health which impacts farm productivity. These three areas of farming are identified to gain the most with cover cropping:
Soil health and fertility
Increases soil organic matter
Improves soil microbiota
Reduces nitrate leaching
Improves water retention
Pest and disease control
Can reduce the use of chemical fertilisers
Increases resilience to extreme weather conditions
Can increase crop yields
Introduces income incentives with carbon farming
Both research studies and firsthand farm experiences associated the benefits mentioned above when cropping is integrated appropriately in every farming calendar.
Incorporating cover crops is a long-term investment that could bring new overhead costs to farms. Consider cropping as a strategy for farm longevity that builds soil health and consequently, farm productivity.
Do cover crops actually increase yields?
Yes and no. The results will depend on a variety of factors such as climate, prior soil conditions, and even the primary crop grown on the farm.
One study published in 2020 found that fields with vegetable produce resulted in greater yield improvements when cover crops were introduced compared to grain and oilseed yields.
Similarly, changes in yield could take longer for some farms than for others. Some farms report improvement after a year while others took 3-5 years for results to be apparent.
Droughts or heavy rainfalls also affect yield with cover crops. Some farms see increases during a drought year indicating that this agronomic method improve resilience.
Advancing sustainable agriculture with cover crops
Just like people, plants need air to live. Specifically, plants uptake carbon dioxide in the atmosphere. CO2 is broken down and oxygen is released by plants as they use some of the carbon to carry on with growth functions.
As part of their biological processes, plants stow away carbon in their leaves, stems or trunks, and roots. Some will eventually be released back into the atmosphere while some will accumulate in the soil where the plants live (and die off).
The process of capturing and storing carbon is called carbon sequestration. Whether the carbon amasses in trees or soil for the long-term, plants are a primary driver for this phenomenon through photosynthesis.
Cover crop carbon sequestration
Carbon sequestration happens naturally with plants and soils, or more recently, through technological advancements to help mitigate climate change.
In agriculture, farmers can add more carbon to croplands by sowing certain plants instead of letting land lie fallow. Cover crops can help soils sequester carbon year-long enhancing the capacity of agricultural lands to take in emissions.
Additionally, green manure adds more carbon to the soil as it is tilled under the ground instead of harvesting. This gives the crop the chance to break down naturally which in turn incorporates more organic matter in the soil.
Organic soil carbon helps determine soil health. And healthy soils promote crop quality. It’s a mutually beneficial feedback loop that enhances agricultural productivity with other environmental co-benefits.
Building carbon in the soil takes time. Cropping along with other regenerative agricultural practices isn’t a one-time, short-term application. Incorporating this practice over many farming years usually provide longer-term effects, one that helps with farm sustainability for future generations.
The potential of cover crops for carbon farming
A study on cover crops found that it has a global potential soil carbon sequestration rate of 0.22 PgC yr-1 in the top 30 cm. The rate increases to 1.4 PgC annually when cover cropping is utilised in conjunction with no-tillage farming.
Cover crops enhance soil sequestration benefiting on-farm productivity and global atmospheric CO2 removal when done wide-scale. This is why cover crops for carbon farming is often mentioned as an agricultural practice recommended for it.
Carbon farming involves shifting to farm practices that enhance land-based carbon sequestration to help mitigate climate change. Farmers engaging in carbon programs get income benefits while adopting regenerative practices on the farm.
→ How can you benefit from cover crops for carbon farming and other practices? Check out our carbon program
Cover crops management and selection
Prior planning is needed to implement cover cropping. Clarify primary goals right from the beginning which can depend on your farm situation. Maybe green manure is best suited, or maybe your farm needs help with erosion or to increase soil organic matter.
Other crucial aspects to have a successful go at cover cropping are:
Crop type and diversity: Legumes (ex. clovers, vetch, peas, beans) for nitrogen fixing or non-legumes (ex. cereals, forage grasses, broadleaf species)?
Cropping management system: with tilling, with crop rotation, or others
Growing window: When to sow and when to terminate season’s growth
When planning to engage in carbon farming, expert agronomists can advise whether cover crops for carbon farming is appropriate for your operation or not. Don’t just initiate cover crops for carbon farming without research or plans, a carbon programme can help create the right agronomic plan for your carbon farming journey.
Smit, B., Janssens, B., Haagsma, W., Hennen, W., Adrados, J. and Kathage, J., Adoption of cover crops for climate change mitigation in the EU, Kathage, J. and Perez Dominguez, I. editor(s), EUR 29863 EN, Publications Office of the European Union, Luxembourg, 2019, ISBN 978-92-76-11312-6, doi:10.2760/638382, JRC116730
Porwollik, V., Rolinski, S., Heinke, J., von Bloh, W., Schaphoff, S., Müller, C. (2022). The role of cover crops for cropland soil carbon, nitrogen leaching, and agricultural yields — a global simulation study with LPJmL (V.5.0-tillage-cc). Biogeosciences. Vol. 19, 2022. 3, 957-977. https://bg.copernicus.org/articles/19/957/2022/. doi: 10.5194/bg-19-957-2022
Chahal, I., Vyn, R.J., Mayers, D. et al. Cumulative impact of cover crops on soil carbon sequestration and profitability in a temperate humid climate. Sci Rep 10, 13381 (2020). https://doi.org/10.1038/s41598-020-70224-6
Clark, A. (2015) Cover Crops for Sustainable Crop Rotations. Sustainable Agriculture Research & Education. https://www.sare.org/wp-content/uploads/Cover-Crops-for-Sustainable-Crop-Rotations.pdf
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