The objective of regenerative farming systems is to develop soils with a robust microbial community which can supply all of a crops nutritional requirements without the need for added fertilizers. The pathway to getting there is to harness the photosynthetic engine every day of the year possible and cycle as large a volume of carbon as possible as a food source for soil biology.
While on this pathway, one of the most valuable things we can do is, in Michael McNeill’s words “stop poisoning your soil!”
One very significant way many farmers poison their soil and inhibit their microbial community is with nitrogen fertilizer applications. The less carbon that is in the soil, the less biological buffering the soil has, the more pronounced the damage from nitrogen applications is to the soil microbial community. In a previous post I described how to buffer nitrogen applications so as to not have this damaging effect.
In this conversation, Larry Phelan desrcibes the capacity of soil organisms to absorb the excessive nitrogen that is so often applied, and then release it later in the crops development cycle.
John: What you’re describing, in essence, if I’m understanding you correctly, is the capacity of biology in the soil to absorb large amounts of nutrients that are applied and to contain those nutrients within their cells and then release them over a period of time. Is that what you’re describing?
Larry: Yes. So, even in this artificial situation that we created—where we put inorganic fertilizer into a soil that had an organic history—even in that situation, that organic soil from that organic farm had enough carbon lying around that those microbes could actually use that inorganic form of nitrogen, in combination with the carbon that was there, and then bring that into that microbial community. As they then die off and you have other organisms that are feeding on those microbes, they then allow for the mineralization of some of these nitrogenous compounds, and then it becomes available to the plant.
To follow up on this, we studied the dynamics of nitrogen across the growing season in these organic and conventional corn fields. Just as we would have expected, when you look at a conventional system, where in the spring the farmer is putting down relatively high levels of soluble fertilizer and really not much carbon, other than maybe some plant residue, you see huge fluctuations in terms of the availability of that nitrogen. So, of course, before fertilization, nitrogen levels are very low, so the farmer applies the fertilizer. Now they shoot way up, well above what the plant can use, and then over the course of the growing season that nitrogen declines.
But if you look at that same pattern in an organic system, what we found was that the levels of soluble nitrogen in the soil solution generally were lower overall, and they also didn’t vary much during the course of the year. That plant was getting this constant supply of nitrogen throughout the growing season. What we found when we compared these farms was that, overall, there was no difference in terms of the production at the end of the year between the organic and the conventional farms.