Good morning, from Alexandria, Minn., Mackane Vogel here, with this week’s cover crop connection. I’m here at the Soil Management Summit and this morning we are going through some live demonstrations. Why don’t we check in with Anna Cates of University of Minnesota Extension for a live cover crop demonstration.

“So as the plant pulls in carbon from the atmosphere, it’s building this biomass above ground — the shoots — it’s building those roots below ground and then it’s also sloughing off a lot of carbon in the form of exudates. So root exudates are what we call the kind of excess carbon that the plant gives up and that microbes take up to live on the plant. So, microbes like to live right on the surface — those roots — it’s like living next to a soup kitchen or something like that. They can just get as much food as they want, whenever they want to. The rate of nutrient cycling on the surface of the root can be four or five times higher than in the rest of the soil. That is because the microbes are there, they have ready access to food, and so they are able to do the things like transform an organic nitrogen into plant available nitrogen or plant available phosphorus and other nutrients so that the plant can take those up. So, what are root exudates, what are they made of? They are mostly just sugar — just carbohydrates — 85-90% sugar and carbohydrates. And so, for the microbe, it’s like your kids eating mac n cheese every single day. They are psyched, they are happy, they are moving along. The microbes like that stuff. The other part of it is organic acids and that can actually affect the structure in the soil. This organic acid can leach into the soil and liberate organic matter that was otherwise bound up with the clay particles. So you’ve got these two elements of the root exudates that help to speed up nutrient cycling — the one is just feeding microbes and keeping that population happy and the other is liberating some organic matter from the soil. 

Lots of good stuff going on this week at the Soil Management Summit in Alexandria, Minn. Make sure you stay tuned in the coming weeks for more content.