These ﬁve principles of soil health were developed by nature, over eons of time. They are the same anyplace in the world where the sun shines and plants grow. Gardeners, farmers, and ranchers around the world are using these principles to grow nutrient-rich, deep topsoil with healthy watersheds. I credit Jon Stika (author of A Soil Owner’s Manual), Jay Fuhrer, and Ray Archuleta for being the ﬁrst, to my knowledge, to refer to these as the “ﬁve principles of soil health.”
Principle One: Limit Disturbance
The ﬁrst principle is to limit mechanical, chemical, and physical disturbance of the soil. Where in nature do we ﬁnd mechanical tillage? Nowhere, of course!
Humans have been tilling the soil for thousands of years, and as modern technology has increased our ability to till more acreage faster, harder, and deeper, the damage done becomes ever more serious. Widespread tillage may make certain tasks easier for the operator, but it destroys soil structure and function. In his book, Dirt: The Erosion of Civilizations, Dr. David Montgomery notes that the demise of civilizations throughout history has been tied to the degradation of their soil resources. The principal contributor to that degradation was, of course, tillage.
Many producers believe that by tilling they improve soil function. Nothing could be further from the truth. Tillage immediately destroys soil aggregates, signiﬁcantly decreases water inﬁltration rates, and accelerates the breakdown of organic material, among other effects. During this intrusive process, oxygen is infused into the soil, which stimulates particular types of opportunistic bacteria that quickly multiply and consume the highly soluble carbon-based biotic glues. These highly complex natural glue substances hold the micro and macro aggregates (composed of sand, silt, and clay particles) together. When the glues are gone, the silt and clay particles ﬁll the voids, which reduces porosity. This reduction results in anaerobic conditions in the soil, altering the type of soil biota, which in turn may lead to an increase in pathogens and loss of nitrogen in the system because of an increase in denitrifying bacteria. Carbon dioxide is released into the atmosphere. As microbes die they release soluble forms of nitrate nitrogen into the soil solution, which stimulates weed growth. Tillage also diminishes complex mycorrhizal fungal networks. The severed hyphal network can no longer deliver complex amino acids and other complex organic/inorganic molecules, thus impacting plants, animals, and humans. Fewer nutrients for the plants also means fewer nutrients for animals and people.
This is the main reason the soils on my ranch saw organic matter levels drop from an estimated over 7 percent pre-European settlement to less than 2 percent at the time Shelly and I purchased the land from her parents. Consider that organic matter (carbon) controls 90 percent of soil functions related to plant growth, and you understand why tillage is so destructive.
Principle Two: Armor the Soil Surface
The second principle is to maintain armor (of plant residues) on the soil surface. Where in a healthy ecosystem do you ﬁnd bare soil? Your ﬁrst response might be, “Gabe, there are plenty of places where the soil is bare!” Sadly, yes, but is it healthy soil? If bare soil was normal in nature, then why do weeds grow whenever we till an area? Nature is trying to cover the soil! The truth is there should not be many open expanses of bare soil, because bare soil is a sure sign of a dysfunctional ecosystem. I often hear producers who live in drier environments claim that their land has always had some areas of bare soil. But historical records, including old journals, show us that even the areas we now consider deserts were once covered with vast grasslands. Recently in Oklahoma, a farmer told me that his grandmother came in a covered wagon in the 1800s to settle what is now their property. She said that the prairie grasses were so tall then, a man riding on a horse often could not be seen! What an amazing contrast to the reality of the Oklahoma landscape today.
I learned the hard way about the value of armoring the soil during those years of hail back in the 1990s. The hail knocked down the vegetation, and I saw how all those felled plants protected the bare soil. The following year I noticed that this crop residue inhibited weed growth; kept soil temperatures down during the heat of the summer; reduced evaporation rates; and provided valuable soil organic material, which was cycled by the earthworms that seemed to magically appear. This armor is also home to a myriad of microorganisms.
When a raindrop hits plant cover instead of bare soil, much of its energy is dissipated, thus protecting the soil from water erosion. Drive through any crop-growing region anywhere in the world where there is tillage and you will see soil being carried away by the wind. Wind erosion is almost as prevalent today as it was during the Dust Bowl. While writing this book, I made a trip to central Oklahoma, and authorities there had to close an interstate highway because of low visibility due to blowing soil. This is a travesty! Consider this: One ton of topsoil spread across a 1-acre ﬁeld would have the same thickness as the sheet of paper these words are printed on. Picture that, and then ﬁgure: How many tons of topsoil were lost in the wind that day in Oklahoma?
As you reduce mechanical, chemical, and physical disturbance, allowing your soil biology to improve, a new challenge may emerge: keeping up with the continuing need for new armor. As soil health improves, earthworms and other soil biology will cycle through surface residues more and more rapidly. In the years following the hail and drought on our land, the biology in my soil multiplied rapidly. The soils on Brown’s Ranch are now so biologically active that I’ve seen an inch-thick residue disappear in six weeks! I address this issue by increasing the amount of carbon relative to nitrogen in my crop rotation. In practical terms, I reduce the amount of legumes in my cash crop rotation and in my cover crops.
Another way to promote thick armor is to grow a high-carbon cover crop, allow it to mature to the point where it’s starting to pollinate, and then graze it at high stock density. I allow the cattle to consume some of the plant material, say 25 percent of the above ground biomass, but I make sure that they also knock down a thick layer of litter that will armor the soil. This is important on the native rangelands, too. At all costs avoid overgrazing, which creates bare ground. If bare spots do show up, use livestock impact to help those bare spots recover. Bale grazing is also a good way to armor difﬁcult bare spots on your operation.
The fact that armor buffers the temperature ﬂuctuations of the soil beneﬁts both plants and soil biology. Many producers do not pay enough attention to soil temperatures, but temperature can have a dramatic impact on plant health. Consider the following:
- When soil temperature is 70 degrees Fahrenheit (21 degrees C), 100 percent of soil moisture is available for plant growth.
- At 100 degrees F (38 degrees C), only 15 percent is available for growth, the remaining 85 percent is lost due to evaporation and transpiration.
- At 130 degrees F (54 degrees C), 100 percent of the moisture is lost to evaporation and transpiration.
- At 140 degrees F (60 degrees C), soil bacteria die.
As producers, we make our living from growing plants. It’s in our best interest to give our plants the best habitat possible, especially below the soil surface. Keeping the soil well-armored should be one of our top priorities.
Principle Three: Build Diversity
The third principle is to promote diversity on as many fronts as possible. My son, Paul, taught range management at the local community college for ﬁve years. Each year he brought his students to one of our pastures and had them collect as many different grasses, forbs, and legumes as they could ﬁnd. One year the students collected over 140 species! That is the level of diversity we ﬁnd in a natural (well, as natural as it can be in this day and age) ecosystem. Lewis and Clark found that level of diversity when they explored the Missouri River system in the early 1800s, including diversity of plants, animals, and insects. The rich, deep topsoils that once covered large parts of this planet were all developed over time due to this diversity.
Let’s consider the current agricultural production model. I can drive for hundreds of miles throughout the Midwest and not see any crop other than corn or soybeans. In the Southeast I see cotton everywhere. In the Paciﬁc Northwest it is wheat. These monocrops are the opposite of diversity.
Farmers need to pay more attention to the four crop types: cool-season grasses, cool-season broadleaves, warm-season grasses, and warm-season broadleaves. Each of these crop types inﬂuences a ﬁeld ecosystem in a different way. If we examine a healthy pasture, we will ﬁnd examples of all four of these crop types, in varying proportions depending on location. It stands to reason then, that we should have all four of these crop types in our rotations. The vast majority of producers focus only on the potential proﬁt a particular crop may bring them that year; they do not look at the ecological capital that diversity builds. If a pasture ecosystem in its natural state includes as many as one hundred different species of grasses, legumes, and forbs, how can we possibly expect the system to function well if we reduce plant diversity to only one or two species? If you want to improve your soils, you must add diversity either by diversifying your crop rotation or by adding cover crops.
Principle Four: Keep Living Roots in the Soil
The fourth principle is to maintain living roots in the soil as long as possible throughout the year. I am always disappointed when producers harvest a grain crop and then leave that land sitting idle without any living roots in the soil until the following year. In October 2017, I drove from my home near Bismarck to Butte, Montana, a distance of over 650 miles. How many green growing ﬁelds did I see, once I left my ranch? Only one! Only one farmer along that whole stretch had taken the time to plant something after the season’s harvest. It was clear that the other growers had not learned the importance of pumping liquid carbon into the soil to sustain soil biology. Here’s an analogy: A farmer would never leave their livestock unfed for months at a time. Why, then, do farmers not think to feed their “underground livestock” through the winter? People often ask me, “What is the one thing you have done that has made the biggest difference to your soil?” The answer is simple: “I grow plants!”
Never, ever pass up the opportunity to convert solar energy into biological energy. As soon as I am done harvesting one crop, be it by combining or grazing, I immediately seed another crop or cover crop. Think of how this ties to the nutrient cycle. If we are not pumping liquid carbon into the soil, we are not feeding soil biology; if we are not feeding soil biology, we are not cycling nutrients. Once you understand these simple principles, you will have new insight into why many producers need to use copious amounts of synthetic fertilizer to grow a crop. Their soil’s natural fertility has been starved out.
In many areas of the country, cover crops planted after a cash crop will not put on much top growth because the number of frost free days are limited or moisture is limited. Many years, I seed a cover crop following a cash crop only to see it grow perhaps three inches tall before frost kills it. This is not a failure! Even though above-ground growth isn’t much, those little plants have produced plenty of roots underground, and that is what matters.
If moisture is an issue in your area, growing plants is even more important because the only way to increase the water-holding capacity in the soil is by increasing organic matter. Approximately two-thirds of any increase in organic matter is due to roots. It is critically important to have as many roots in the soil as long as possible throughout the year. In Roots Demystiﬁed, author Robert Kourik describes a single cereal rye plant with a root length that measured 372 miles! The root hairs of this plant measured 6,123 miles for a total length of 6,495 miles! That will certainly increase organic matter!
Principle Five: Integrate Animals
The ﬁfth principle is to keep animals present in the agricultural landscape. Another tragic ﬂaw of the current production model is the removal of animals from the landscape. Take a look back at how our grandparents farmed a century ago. Nearly every farm had beef or dairy, along with hogs and poultry. Horses were used as draft animals. Today we have moved the poultry and hogs into conﬁnement buildings, the beef onto feedlots, and the dairy into very large conﬁned operations. In many parts of the world, one can drive for hundreds of miles without seeing a fence, let alone an animal.
What difference does this make? To answer that we must understand how soils were formed. Centuries ago, tens of millions of bison, elk, deer, and other ruminants roamed the North American continent. These ruminants took a bite of a plant here and another there, causing those plants to release root exudates in order to attract biology that supplied the nutrients needed for regrowth. The presence of predators kept the herds of ruminants on the move, and they often did not return to the same spot for long periods of time. The plants thus had ample time to fully recover, all while pumping massive amounts of carbon into the soil. Add to this the myriad of insects, birds, and other wildlife that also lived in these environments, and it all added up to a very healthy, optimally functioning ecosystem.
Today, with grazing animals almost entirely removed from the world’s grasslands, there is much less carbon cycled through the system. There are those who blame cattle for climate change. That viewpoint is too simplistic; it does not take into account the larger picture of how ecosystems function. The best-proven way to transfer massive amounts of carbon dioxide out of the atmosphere and into the soil is by maintaining a landscape that includes grazing animals. It is not the cattle that are the problem, it is our management of them! One of the best presentations of this argument is put forward in the book Defending Beef by Nicolette Hahn Niman.
Integrating multiple species of animals throughout Brown’s Ranch has led to much larger amounts of carbon in our ecosystem. This has not only improved soil health, it has also signiﬁcantly increased our proﬁtability. I encourage all operators to take advantage of the many beneﬁts that animals offer.
Gabe Brown is a pioneer of the soil-health movement and has been named one of the twenty-five most influential agricultural leaders in the United States. Brown, his wife, Shelly, and son, Paul, own Brown’s Ranch, a holistic, diversified 5,000-acre farm and ranch near Bismarck, North Dakota.
This excerpt is adapted from Gabe Brown’s book Dirt to Soil: One Family’s Journey into Regenerative Agriculture (Chelsea Green, 2018) and is printed with permission from the publisher.