John Kempf explains how cover crops are supposed to unlock soil minerals through microbial activity, but warns that released phosphorus and potassium may not be enough for the next crop. Heavy pesticide use, especially glyphosate, can cripple the microbiome, so real nutrient gains take three to five years.
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One of the ideas that's strongly promoted by many advocates of a regenerative agriculture approach is that of tapping into your soil reserve minerals and reducing your input costs, reducing fertilizer costs. And this is a very important conversation for us to have in the present difficult macroeconomic conditions. We understand that many soils, not all, but very sandy soils, are a particular case in point of being an exception. And there are others as well. You can measure this with, you can measure a soil's total nutrient reserves with what is called a total digestion analysis. It's run by a number of different laboratories. And the total digestion analysis can show you the reserves of phosphorus and potassium and calcium, magnesium and other elements that are held in the soil reserves that typically do not show up on a typical soil analysis and that may be accessible by biology. So the, the historical, the proposal commonly has been that to reduce input costs, to reduce fertilizer applications, we will plant cover crops and have those cover crops, the microbiome of those cover crops absorb nutrients, solubilize nutrients and transport, transfer those nutrition, those nutrients into the crop biomass. And then that, as that cover crop biomass gets cycled, we now have an increased availability of nutrients, particularly phosphorus and potassium and other elements as well, for the benefit of the following crop. And this is, this is generally accurate, but there are a couple of potential challenges with it. One is that the amount of phosphorus and potassium released may not be adequate for the following crop that you're wanting to produce. And the other possibility is that in many cases, when soils have a history of strong pesticide use, a lot of historical glyphosate use in particular, there is a suppression, even when you grow a cover crop. There isn't the dramatic immediate release of these nutrients that occurs if you grow cover crops over time. And so there is, there is this understanding that there is this, this trajectory, this upward trajectory that we get better and better nutrient release over a three to a five year period as a result of continued cover crop applications. And that is in large part due to the recovery of the soil microbiome. So, and of course, in today's macroeconomic conditions, putting out a cover crop is, is still a lot less expensive than a fertilizer application in many, in many cases. But putting out cover crops is, also has its own set of challenges from a planting and timing perspective. And I'm a very strong advocate for using cover crops just for the record.
