When I first started farming, I bought some cows. I was a cattle farmer. I eventually figured out that if I could take good care of the grass, it would take care of the cattle. When I determined the cattle were simply a tool to manage the grass, I became a grass farmer. A few years ago I figured out that if I can take care of the soil, and the soil life within it, that would take care of the grass, which would then take care of the cattle. In other words, plants are simply a tool to manage the soil. So now I am a soil farmer.
I wrote an article last year about Jean Baptista Van Helmont. He was a scientist in the 1600s who wanted to learn how plants grew. If you recall, he was arrested for his science, as it was against modern thinking at the time. His conclusion was that plants grow from water because the weight of the soil at the beginning of the experiment was nearly the same as at the end. His plants grew by adding only water. Modern thinking at the time was that plants grew from using up the soil. Wait a minute: is that not the same modern thinking that we use today? We add fertilizer to the soil and we have to keep adding to the soil because it gets used up. Think about it. Do you believe that the plants grow from the soil?
Let us look at this a little closer. Jean did not know about photosynthesis. Photosynthesis is when the plant takes carbon dioxide (CO2) and water (H2O) and combines them by using sunlight energy to form a simple sugar called glucose (C6H12O6). Did you know that a plant could grow without soil? In a crack in a rock on a mountainside, a spruce tree can grow. Where does it get its nutrients? From the air.
Over 95 per cent of the makeup of any plant comes from the air with some assistance from soil organisms. If we look at the typical dry matter composition of a plant, it looks something like this — carbon: 45 per cent, oxygen: 45 per cent, hydrogen: six per cent and nitrogen: 1.5 per cent.
Any other element in a plant will make up less than one per cent. Most are measured in parts per million. The rest of the elements we need to grow plants come from somewhere else. This could be from the soil or straight from rock, with the help of our friends mycorrhizal fungi.
My point is that the plants do not need soil to grow. However, the soil does need the plants. Photosynthesis by the plants produces sugars, which are the foundation to life. It is the plants that push sugar out of the root tips as they grow that glues the soil particles together causing good aggregation. The plants build the soil by taking H, O, C and N from the air and adding it to the soil. We do also have to give credit to the soil microbes. In symbiotic relationships with the plants, many of our microbiotic employees also help to build the soil. For example, mycorrhizal fungi produce glomalin, which is a glycoprotein. Most tests greatly underestimate the amount of glomalin in our soils, which can account for up to one-third of the organic carbon stored in agricultural land. However, we need healthy soils with good organic life to do so.
I have often heard the recommendation that producers need to cultivate their pastures every eight to 10 years in order to release “bound up” nutrients. I totally disagree with this practice. I am trying to build up my soil by making nutrients become “bound up” in it.
When you break up that pasture, nutrients are released. This allows you to mine the land and deplete it faster. The problem is that it works, as producers get a really good crop for a few years by mining the nutrients. But this is a short-term gain that comes at the cost of depleting the soil.
Building soil also increases the water-holding capacity by putting more carbon back into the soil. Humus can hold up to nine times its weight in water.
The best way to put organic carbon back into the soil is through exudation from the actively growing roots of the Poaceae family of plants. This includes pasture grasses and cereals. Exudation is when the root tips are pushing out sugars as they grow, which glues the soil together. The breakdown of plant material and their fibrous roots is also an important source of carbon in soils. The more active the plant roots are, the more carbon is added. Also, the more diverse the plants, the better it is for your soil life. We need to stay away from monocultures. Polycultures create healthy ecosystems.
I am experimenting with pasture cropping; I want to have perennial pasture grasses and cereals together. The ongoing carbon inputs from the perennial grasses create highly stable forms of soil carbon, while the short-term, high-sugar forms of carbon exuded by the roots of the cereal crop stimulate microbial activity. This is a good combination in building soil. I also want to have some legumes to fix nitrogen as well as some plants that open up the soil like tillage radish and sweet clover. These are not meant to be a forage, but more of a soil amendment. These big roots can dig down and open up the soil allowing water and air infiltration.
In a healthy ecosystem, plants grow the soil, not the other way around. Of course, this is all tied together with the recycling of nutrients provided to us by our livestock, that recycle 80 per cent of what they consume. I am sure glad that they are so inefficient; it is almost like they were meant to be that way. My lesson learned: Use plants to build soils and use livestock to manage the plants. It’s been working for centuries without us.