Balancing Carbon and Nitrogen

August 7, 2023

Carbon and organic matter are extremely important from a soil health, plant health, and yield perspective, but we have to keep in mind that it is not just carbon that we care about, but the balance between carbon and nitrogen. These two really do complement each other.

Too much nitrogen, especially the soluble forms, will break down carbon and organic matter and make it really difficult to improve soils long-term.

On the other hand, there are a lot of crops being grown in organic systems that are nitrogen deficient. Part of this comes from the understanding that carbon is the most important thing. The other part may come from the thought that nature can provide all the nitrogen it needs because the atmosphere is 78% nitrogen.

What we as regenerative growers need to remember is that any time we apply nitrogen, wood chips, manure, composts, etc., we are likely shifting that carbon to nitrogen ratio – that is, unless we understand how to keep things in balance.

Aside from those inputs, we could also look at the impact of the cash crop or cover crop that is being grown. We know that alfalfa, clover, hairy vetch, peas, etc. all add nitrogen to the soil. If the C/N Ratio is balanced, the optimum for a cover crop would probably be to keep it balanced by using a mix of legumes and non-legumes.

Another important part is the stage of termination for the cover crop stage. A mature crop will add more carbon and organic matter to the soil; whereas a young crop will tend to add more nitrogen, and, in the case of high carbon content, even improve soil biology faster. So it becomes very important to know your situation and what is optimal to balance your soil for optimal production.

My main reason for wanting to talk about this is that I see so many farmers and gardeners that are over-applying carbon, in the form of humates, biochar, imbalanced composts, manure bedded with too much carbon such as shavings, or even using the good cover crops and terminating them when too mature, then saying it doesn’t work.

While conventional agronomy perhaps overemphasizes nitrogen, regenerative farmers need to recognize that nitrogen is important. When there is too much carbon, or rather imbalanced carbon to nitrogen ratio, the nitrogen will go first to breaking down the carbon, leaving the crop suffering for nitrogen.

In summary, we want to remember that both nitrogen and carbon are important, but it is the level of each and the balance to each other that produces a healthy crop.