What’s Up With Your Soil?
How well do you know the soil that grows your food? Do you know whether your soil is “healthy” or “unhealthy” (or somewhere in between)? Even the most advanced growers will admit that there is always more to learn about the soil and how to nurture nutrients, biota, microorganisms and soil structure. Every year brings new opportunity to learn more about your soil and improve its health. The rest and rejuvenation that fall and winter offer are the perfect time to start turning your attention to this important work.
This article is meant to act as a guide for growers of all levels. If you are already familiar with one area and don’t wish to read it, simply click the title of the section you wish to skip to and start from there:
Identifying Your Soil Type
Soils are classified based on their ratio of the three main soil textures: sand, silt, and clay. They can be further described with the term “loam,” which means they contain the fertile soil component humus. You may know what sort of ratio and fertility your soil holds based on your geographical location (i.e., sandy loam, silt loam, sandy clay, etc.). But, even within regions there can be a great diversity of soil texture based on what has occurred on that exact piece of land in the last several hundred years.
If you do not already know what type of soil your land is on, use this flowchart to help determine the natural texture of your soil. It is important to note that soil texture and soil slope are inherited characteristics of your land. In other words, you cannot change the natural soil texture and soil slope of the land you are on. What you can change based on your land management techniques are the dynamic characteristics of your land, such as the type of vegetation that is grown there, nutrient cycles, water flow, soil microbiology, and the level of soil organic matter.
Once you have determined your soil texture, the next step in understanding your soil is learning what it means to have that certain soil texture. The University of North Carolina Extension service has an extensive article that outlines the physical properties of soils and how those properties affect growers.
What Is “Healthy Soil”?
Now that you know what type of soil you are working with, you will want to have a clear understanding of what makes your particular soil “healthy” or “unhealthy”. Only living things can have “health”, which means we must view the soil as a living, breathing organism that requires all the things we and our fellow organisms do to thrive on this planet: food, water, oxygen, etc.
Soil health is the continued capacity of the soil to function as a vital ecosystem that sustains plants, animals and humans. In order to achieve this level of support, we must nurture the life within the soil, which includes billions of bacteria, fungi and other micro and macro organisms living in symbiotic relationships that mirror those we see above the soil.
When you are successfully nurturing the life in your soil, you will see it reflected in the life that grows from your soil – the plants. This is why the work of establishing and improving soil health is critical to those of us who grow food.
The Four Soil Health Principles
There are four accepted soil health principles to keep in mind when approaching the work of establishing and improving soil health. All of your soil health management practices will fall into one of these categories. As with the flora and fauna you nurture on your land, it is important to incorporate diversity into your soil health practices - so keep all four principles in mind when crafting management techniques.
- Minimize disturbance.
- Maximize soil cover.
- Maximize biodiversity.
- Maximize the presence of living roots.
The glue that holds healthy soil together is soil organic matter. (Wondering what soil organic matter is? Find out here.) Each of these four principles enables SOM and supports all the benefits that come along with it. As you engage more with your soil and attempt to improve its health and robustness, keep in mind that building soil organic matter is key to achieving healthy soils.
Soil Health Checklist
For starters, the Natural Resources Conservation Service division of the USDA has put together a checklist for soil health-minded growers, which gives an outline of management techniques related to the four soil health principles. The following are common techniques that can be used to achieve the four soil health principles.
- Ways to minimize disturbance:
- No till
- Low till
- Mulch tillage
- Ways to maximize soil cover.
- Cover crop
- Ways to maximize biodiversity.
- Ways to maximize the presence of living roots.
How to Measure Soil Health
The soil health principles and soil health checklist are general guidelines for land management practices that will improve and maintain soil health. But how do you know if these practices are working? And even if they are working, how can you fine-tune them even more to fit your specific needs?
This is where combining the science of nutrient measurements and the art of soil health intuition comes into play. Becky Maden, a member of the University of Vermont Extension team, has written extensively for us on this subject: her article, Mastering the Art of Soil Nutrients, is an excellent resource on this topic.
Soil tests are crucial to understanding how your management techniques impact the health of your land. Learn how to take a soil sample and where to send them for results by reading our Soil Test blog post. You will likely be best served by utilizing your state and regional resources, as they will specialize in your soil type. Click here to see a directory of soil test labs by state.
Most soil test labs recommend that you always test your soil at roughly the same time in the year so you get an apples-to-apples comparison from season to season. This is why many growers choose to do soil tests in the fall, when the majority of their cash crops are finished for the season. It is also best for consistency of results and amendment recommendations to use the same soil testing lab from year to year, as labs vary slightly in their metrics. Some growers also choose to get results from two different labs as an added level of knowledge.
How to Improve Soil Health Based on Your Measurements
Once you’ve taken the important step of measuring your soil’s nutrient levels with a soil test, you now need to know how to interpret and act on the results. SARE (Sustainable Agriculture Research & Education) has an excellent guide to interpreting soil test results that includes sample test results and interpretations based on the recommendations made by the lab. The guide also breaks down interpretations based on certified organic growing or using sustainable practices without an organic certification. Becky Maden from the University of Vermont also has advice about how to read your soil test results and how to act on them – her article on soil fertility can be found here.
There are of course “best practices” for improving soil health that will help reflect positive results on your soil tests from season to season. Read farmer Kate Spring’s article on the regenerative agriculture techniques she uses at Good Heart Farmstead to build healthy soil (and sequester carbon!).
How do you improve your soil health from season to season? Tell us about your best practices in the comments below!