Here’s the Dirt on Healthy Garden Soil
By Jayne Rising
When you look at the soil in your garden, do you see healthy garden soil? Or, do you see a pile of lifeless, inert stuff? Soil is an ecosystem in its own right, with flora, fauna, and chemical reactions all its own. Healthy garden soil is full of life, and in this article, we’ll dig in! (Pun intended!)
Understanding soil is an important part of self-reliance.
What are the different soil types and compositions of those types?
Soil type classifications are in a triangular fashion between clay, silt, and loam. Clay soils hold water very well but don’t drain well, and roots have difficulty growing through it. Whereas sandy soils drain well and plant roots grow easily, it holds little in the way of nutrients. Silts have more nutrients but drain too quickly. An ideal soil is more of loam, with the three best qualities: lots of nutrients, drains well but not too fast, and plant roots can easily grow in it. As always, the usual life situation is less than ideal.
Soil composition by volume is 20-30% air, 5% organic matter, 45% minerals, and 20-30% water. Soil also contains an incredible variety of micro fauna: earthworms, beetles, and other beneficial life. Earthworms, for example, help aerate the soil and perform many chemical reactions that keep soil healthy. And let’s not forget worm castings! Those are a very rich source of many nutrients. Soil also produces antidepressant effects on exposed skin! Perhaps this is why we feel so much better after digging in the dirt. [source]
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What is pH, and what are the effects of pH on nutrient uptake?
Soil pH gauges the alkalinity or acidity of soil using a scale of 1-14, with seven as the neutral mark. The closer to 0, the more acidic the substrate. The closer to 14, the more basic. Most vegetables prefer a pH in the 6.5-6.8 range. However, there are exceptions, such as blueberry, which favors a much more acidic soil.
So why does this matter? Simply put, pH has a direct effect on nutrient uptake. Within a relatively well-defined range, specifically 6-8, plants can take up most nutrients, including primary, secondary, and trace. A few micronutrients such as iron, manganese, boron, copper, and zinc drop off at 7.5. Outside of that range, the roots progressively lose the ability to absorb nutrients from the soil. Imagine you are in a full pantry and can’t eat a single thing. That would be a problem.
What are ways of testing to ensure healthy garden soil?
Soil testing is relatively straightforward, but some tests are more accurate than others. Lab testing is the most accurate and often available through your county’s Extension office. Usually, the lab will test for NPK, organic matter, and pH. They’ll also include very specific lime and fertilizer recommendations. Additional tests for various micronutrients and lead are available for an additional fee.
There are many commercial test kits available, RapiTest being one of the better known. These function by way of a chemical color reaction and typically test NPK and pH. They’re not considered highly accurate but will get you in the ballpark. Metal probes are also available, but I trust chemical color reactions more than those.
So, how do we take a soil sample?
Simple! You’ll need about 1-2 cups per sample if you’re submitting samples for lab testing. Dig down 5-7 inches in several areas of your garden, mix the soil in a bucket, and add water to make a slurry. I tend to draw a W in my beds and take a trowel full from several points along the line.
Important point: if you use a metal probe, you’ll need the slurry to get an accurate reading. Even though the instructions imply that you can stick the probe in the soil and trust the reading, you can’t. Trust me! I have done this and been there. It doesn’t work. As I said, I trust the chemical color reaction more anyway.
What is the best way to amend soil?
Compost, organic matter, mulch, fertilizers, the list of available materials is lengthy. As vegetables are grown in the soil, nutrients are used up and require replacement. In addition to the major three (NPK), a host of secondary and trace nutrients are necessary for healthy plants and yummy vegetables.
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For preppers, it’s really important to stock up on soil amendments or know how to make them, because one day your life might depend on your garden.
The basic ten are:
- nitrogen
- phosphorus
- potassium
- calcium
- magnesium
- sulfur
- iron
- boron
- zinc
- copper
- manganese
- molybdenum
Deficiencies in any of these will lead to problems.
Soil pH can also be adjusted, although this takes time. Acidifiers such as sulfur and gypsum will lower pH, whereas dolomitic lime raises pH.
Nitrogen fixers: Rhizobium, Mycorrhizae
These are microorganisms that can be very useful to promote healthy garden soil. Rhizobium is a bacteria that form nodules on the roots of legumes (beans, peas, clover, and other family members). Rhizobium fixes nitrogen in the soil, helping to rejuvenate the soil in a very natural way. Nitrogen is essential to leaf formation and photosynthesis and is usually the major nutrient drained most quickly. [source]
Mycorrhiza are fungi that form a mutualistic relationship with plant roots. Mutualism is the association between organisms of two different species in which each benefits. [source]
Categories of these symbiotic relationships are:
- Ectomycorrhizal
- Endomycorrhiza
- Arbutoid
- Arbuscular
- Ericaceous
- Orchidaceous
- Monotropic
Different categories form relationships with different plant families.
What are the benefits of these fungi?
Benefits of these fungi include a more well-established root ball that leads to superior nutrient and water uptake, more resistance to both diseases and drought, and enhanced growth of both seedlings and root cuttings. The superior stress resistance yields the potential for less pesticide use, and some species can even remediate petroleum and heavy metals contamination. These are best inoculated into the soil when the plants are young with younger roots. Established plants can form a relationship, but it’ll take some digging in just the right spots.
For those who would like some in-depth scientific information about these organisms:
What are the effects of pesticides on soil?
Generally, pesticide overuse is bad for your soil. Living, healthy soil harbors several beneficial organisms, including earthworms, beetles, and nitrogen fixers, among many others. Many pesticides linger in the soil for years! If you must use them, use them very sparingly. These are the last resort in integrated pest management.
Soil is an incredible ecosystem in its own right, absolutely teeming with life. Healthy garden soil is essential to a productive in-ground, container, or raised bed garden system. Therefore, it pays to know everything we can about it and how to keep it healthy.
For myself, I believe that if I take good care of my assets, they’ll take good care of me! If you’re a soil nerd, be sure to check out Symphony of the Soil – it’s a brilliant documentary that will change how you look at your garden. What have you learned about soils, and how do you care for yours? Share your dirt-y stories in the comments section.
Source: The Organic Prepper
Jayne Rising is a gardener and bookworm with a BS from the University of Wisconsin and a Master Gardener certification. She’s been growing food on her small urban lot since 2010 and teaching others how to do it since 2015. She’s involved in a number of local urban agriculture initiatives, working to bring a sustainable and healthy food system back into the mainstream.
