Soil Balancing, part 5 (carbon and nitrogen)

November 13, 2023

Both carbon and organic matter are extremely important from a soil health, plant health, and yield perspective. At least, that is what the organic growers say. And it’s true.

On the other hand, conventional growers and agronomists say that Nitrogen is extremely important for good growth and crop production. And again, it’s true.

Both are right.

The common mistake is to forget that carbon and nitrogen has to be balanced in order for plants to be exceptionally healthy. Too much carbon, and you get yield and energy drag. On the other hand, too much nitrogen, especially the soluble forms, will break down carbon and organic matter and make it really difficult to improve soils long-term.

It’s really the balance between the two that we care about.

As regenerative growers, we remember that any time we apply nitrogen, wood chips, manure, composts, etc., we are 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 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 needed to balance your soil for optimal production.

On the other hand, if you’ve been overapplying nitrogen, especially soluble forms, you may want to consider applying liquid carbon with your nitrogen, and at the same time reducing the nitrogen rates and putting sulfur and molybdenum with it. You will be able to save on nitrogen costs while increasing efficiency and the crops will still get what they need.

Now I would like to add a few words to the regenerative farmers. There is a popular narrative that when we work with nature, we can get all the nitrogen we need for free, because after all, there are 32,000 tons of nitrogen over every acre of land.

And that is true. Except it can also be misleading, as all farmers know who learn the hard way. Getting all our nitrogen for free is something that has to be earned. First, we have to recognize that the 32,000 tons of nitrogen that are available over every acre of land cannot be used directly by plants. Instead, the nitrogen is fixed by either nodules on legumes such as alfalfa and clover, or by soil microbes called nitrogen fixing bacteria. Second, we have to recognize that soil structure plays an important role in how nitrogen is brought into the system and then “fixed”. Every evening, the earth inhales, and with it goes air that is 78% nitrogen, which is then fixed by nitrogen fixing bacteria. This is how you get nitrogen for free, but you have to have good soil structure or legumes in order for this to work. If you want to learn more about this, you can look at an article from earlier this year titled “Managing Nitrogen in Regenerative Systems”.

In summary, if we want to be regenerative and grow healthy crops, it is imperative that we not take a lopsided approach and focus on just carbon or nitrogen. It is far more effective and productive to keep the two in balance.