Conversations around sustainability, regenerative agriculture, and a financially incentivized carbon offset market have grown louder in the world of agriculture. Private industry, farmers, universities, and governments want to take full advantage of agricultural practices that can benefit the climate and industry simultaneously.
To date, a lot of the focus has been on practices such as including cover crops in cropping rotations or switching from conventional tillage to strip tillage or no-till.
However, many of these conversations have overlooked a substantial but quiet success story – perennial forages, and in particular, alfalfa.
In the table above, we see that alfalfa has huge potential in achieving different sustainability goals. Taken together with traditional cover crops, alfalfa can help realize key benefits to soil health and sustainability. We highlight a few of these major strengths below.
To start, let’s talk about carbon sequestration. A recent Stanford publication found forests, widely thought of as one of the best carbon sinks, may be a less effective sequestration solution than grasslands (i.e. perennial forages) in certain situations.
As CO2 levels rise, many plants have a concurrent increase in CO2 sequestration, whereas forests largely remain unchanged. Results can vary based on things like geography, precipitation, soil type, management, etc., so many findings are going to be generalized. However, this research demonstrates that crops like alfalfa, typically grown over a period of several years, enable maximum carbon sequestration per acre.
Including alfalfa in carbon sequestration models is no small feat. Annual crops like corn and soy are easier to model because management is more predictable and management impacts can be attributed to a single year because they are annual crops.
Despite this challenge, to alfalfa’s impact on carbon sequestration – a perennial, deeply rooting plant – is tremendous. While crops like corn and soy often have a net neutral or negative impact on carbon sequestration, we see documented improvements in soil carbon levels when alfalfa is included as in the rotation. These improvements go beneath the topsoil layers, where cover crops stop, deep into the soil.
Alfalfa’s best known benefit is its ability to fix nitrogen and pass it on to the next crop for utilization, which has tremendous implications for overall greenhouse gas emissions. Alfalfa’s nitrogen contribution to subsequent crops allows us to decrease our synthetic nitrogen needs when rotating to something like corn or wheat. This can reduce the need for nitrogen fertilizer the first year in corn or wheat, and may even extend into year two.
Farmers can reduce their fertilizer bill and the carbon footprint all at once.
Using its deep root structure, alfalfa can help decrease nutrient leaching in deep soil, making it a perfect ally for cover crops that protect the upper soil levels. This benefit has been shown in mine reclamation sites, where it is being planted to reduce toxic metal concentrations in the soils, as well as near groundwater sources, where it can help to soak up potential contaminants such as nitrates.
We are learning in real time how to best measure carbon sequestration practices, while both building and maintaining soil health. Our toolkit is growing and creativity will only help. Innovative agriculture practices and even overlooked crops, like Alfalfa, can drive conversations that support soil health, ecosystem services, and overall sustainability.