Creating Excellent Pastures From the Soil Up
I think we all have our vision of what makes an excellent pasture. We see a thick stand where nearly all the ground is covered by vigorous, rich green plants. We see a myriad mixture of different grasses and legumes. Some of us see forbs as well, while others may think of those as weeds. We have this mental picture of what an excellent pasture should look like, but in all honesty, how often do we really see that on our own place?
In my almost 40 years of working with pastures and livestock, I have had the privilege of visiting 49 US states, ten Canadian provinces and many of the countries we think of as grazing paradise. Ireland, New Zealand, Uruguay, among others. In my experience across the country and around the world, fewer than 5% of the pastures I have set foot in would I consider to have been excellent pastures. If we have this vision of the perfect pasture so firmly etched in our minds, why is it so elusive?
A big part of the answer to that question is out of our sight. It is what goes on below ground and much of it we cannot see with our naked eye. I grew up in the agricultural era when the idea that if you took a soil test and applied the recommended amount of fertilizer, you were taking care of the soil. It took me a lot of years to unlearn that training. There is so much more to the soil than what we can see.
When I was in college in the 1970s, I was told to envision the land as an old-fashioned three-legged milking stool. Those legs were soil chemistry, physical structure, and soil biology. The arm sits solidly atop the stool when the three legs are in balance. But if one leg is shortened, we slide off the stool. It no longer sits solid. In the 20th century most of the attention in soil science was give to chemistry and physics. Soil biology was only mentioned in passing.
Old view: The three legs are the chemical, physical, and biological aspects of the soil.
The first half of the 20th Century is when we learned so much about soil chemistry and the use of soil amendments to make the land more productive. Initially the response was very positive and we were all happy. But along the way, we found a few things that weren’t working out the way we expected them to. One of those surprises was that as we added more synthetic N fertilizer to the soil, organic matter levels declined.
In the second half of the 20th Century, we learned more and more about the physical aspects of the soil and about soil physics itself. We began to better understand the balance of water and air in the soil. We turned irrigation into a precise science where we could put on the ideal amount of water to make our crops even more productive. More productive crops needed more N fertilizer which further decreased organic matter which reduced water holding capacity which increased runoff which increased soil erosion and as crop yields went down irrigated land was abandoned as it became less and less productive.
Here in the first part of the 21st Century a whole new view of soil biology has taken off. What most of us have just recently realized is that for the most of the last century we have been shortening the biological leg of the soil. That has put the stool, rather the whole ecosystem, out of kilter. We have been paying the price for killing the soil through declining natural productivity. The result has been the need for more and more manufactured inputs to produce crops that have less and less nutritional value for our livestock and to us as well.
The newer view of the soil is more of a pyramid perspective. Soil biology is the foundation upon which all other aspects of the soil rests. Soil biology determines soil structure and aggregate stability. Water relationships and aeration, two principal concerns of soil physics, are governed by soil biology. The physical structure of the soil is the middle layer of the pyramid. The cap of the pyramid is soil chemistry which is also largely driven by soil biology through the various mineral cycles. In my time at the University, the greatest attention was given to soil fertility and chemistry with soil physics coming more to the forefront in the latter half of the 20th Century. Now, in the 21st Century, soil biology is the most rapidly evolving agricultural science.
New view: Soil biology must be active and dynamic for the soil chemistry and physics to be functional.
Fortunately, we have learned a great deal in the last few years about what it takes to bring the soil back into a healthy state with all three legs in balance. We have learned that we cannot separate soil chemistry, soil physics, and soil biology into separate sciences. It is all one living, breathing organism that works together to give us healthy landscapes. It takes healthy soil to give us that excellent pasture we are all looking for.
Where do we start on this quest to bring our soil back to life and create the perfect pasture?
We start by putting more energy into the soil. That comes about when we increase carbon flow to the soil. The source of virtually all life and energy on Earth is the Sun. It is the ongoing process of photosynthesis that takes solar energy and converts it into chemical energy that ultimately flows to the soil and all the life that exists below ground. All that life that we don’t see.
The more photosynthesis that we can maintain on every acre for as many days of the year as possible, the more energy and life we can create and maintain in the soil. The key to maximizing photosynthesis is maintaining green, growing leaves on as many acres as possible as many days as possible. Some of you have heard me speak before and you will likely have heard me talk about post-grazing residual. That is the green leaves we leave behind after a paddock has been grazed. Why is residual so important? Because it is what keeps plants growing. You may have heard me talk about plant species diversity in pasture. Why is diversity so important? Because it increases the number of days in the year when there is likely to be green growing leaves. It also changes the shapes and angles of leaves in the canopy to make a more effective solar panel. We have talked about appropriate recovery periods following grazing. Why is recovery important? It
is the opportunity to grow leaves and optimize solar energy capture again.
These three things we think about with our above ground management: Residual, Diversity, and Recovery are the first keys to bringing life back to the soil.
What about the need for fertilizer if we want to have productive pastures?
Once we have a healthy, living soil, natural mineral cycling processes are enhanced. Microbial-plant interactions increase the efficiency at which minerals can be moved from the soil colloids into the plant root system. The idea that a sterile root in the dirt could capture all the necessary nutrients from a diet of synthetic fertilizers was one of the great fallacies of 20th Century farming. We need the complex web of soil life to give us truly nutritious plants.
When we do need to add soil amendments because our farm has been depleted through years of exploitative farming practices, using manures, hay feeding, and cover crops takes us much farther down the path of soil regeneration than does using synthetic fertilizers. In the early transition back to healthier soils, we can use judicious amounts of fertilizer to help accelerate plant growth to get more energy initially into the soil, but chemical dependencies are never a good thing and we should avoid it at all possible.
Another key piece of making soils healthier is to get the pharmaceuticals out of your farming operation as quickly as possible. Herbicides, insecticides, fungicides, and parasiticides are all designed to kill things. How could it ever make sense to apply death to the soil which is above all other things, a living breathing organism. Just remember herbicide, insecticide, fungicide, and parasiticide all rhyme with homicide, suicide, genocide, and regicide.
Written by Jim Gerrish, American GrazingLands Services LLC. You can learn more about Jim at http://www.americangrazinglands.com/about-us-jim-dawn-gerrish