Written by Susan B.
If you’re growing plants in containers, the most important consideration – other than the size of the pot, is the soil you use. And the quality of the dirt you use has a significant impact on how healthy your plants are, and how successful you are at growing them.
What is Soil?
The Free Dictionary defines soil as the earth’s top layer where plants grow. It is made up of mineral and rock particles. It also includes decomposed organic matter that holds water. In physical geography, we define ground soil as the uppermost layer of the earth’s surface. It comprises a combination of disintegrated particles of rock, or stone, humus, and water.
Loamy soil is considered the ideal growing medium. It is perfect because it is a combination of equal parts of three distinct types of dirt: clay, sand, and silt. Clay is useful because it absorbs water so quickly, but its moisture-retaining ability also causes it to compact easily. Sand helps improve drainage in clay soils. But it also helps to prevent soil compaction. Silt contains fine particles. Like clay, silt holds moisture, but the water-holding property causes compaction.
What is Soil Organic Matter?
When we refer to “organic matter,” we’re talking about substances we add to the soil to make it better. “Organic matter” includes things such as compost from your household food scraps. It can also include biodegradable paper, weeds, grass clippings, leaves, plant scraps from pruning), composted manure, shredded wood, green manure (cover crops you grow to till into the soil before planting – typically in vegetable gardens), or mulch. All these substances decompose in the ground over time, releasing nutrients that improve drainage, break up compaction, increase airflow throughout plant roots, and replace the things that nature puts in the soil. However, we remove through repeated planting, digging, the use of chemicals, and environmental factors, many of which contribute to climate change. According to SARE (The Sustainable Agriculture Research & Education Program), “soil organic matter is the very foundation for healthy and productive soils.”
Organic matter improves overall soil health. And our plants will love that, and so will we. It is a combination of living organisms, fresh residues, and thoroughly decomposed residues. Soil microorganisms are the good guys who eat their way through the organic matter, making it break down, and ultimately turn into dirt. The microorganisms that do that are bacteria, fungi, and protozoa. They thrive in the topsoil because organic matter is added to topsoil. But microorganisms are also abundant in the rhizosphere, the area surrounding plant roots.
Bacteria are the first microorganisms to start the decomposition process. Their role in contributing to soil health is to make nutrients available to plants. They dissolve phosphorus so plants can use it, and they get nitrogen to plants.
Fungi are responsible for the decomposition of fresh residues. They soften organic matter, but they also decompose lignin. Fungi grow in abundance in soils that are never disturbed. Although they can attack plants and infect them with downy mildew, damping-off disease, or various types of root rot disease, they are beneficial when helping connect plant roots with the soil.
Protozoa are the only animal microorganism. As single-cell animals, they move around in the soil. Although they can’t be seen, their work in decomposing organic matter is second to that of bacteria and fungi. They eat bacteria, fungi, and other protozoa. Protozoa eat organisms and plant material that’s rich in nitrogen, and by doing so, the excrement they release mineralizes the soil.
Earthworms are vital contributors to soil health. Worms feed on organic matter. As they do that, the organic matter releases nutrients during the decomposition process. Their activity also helps mix organic matter with soil, moving it from close to the surface to the area where plant roots are. Earthworms burrow their way through the soil. As they eat organic matter, the excrement they leave is known as worm castings. Those castings produce rich organic humus.
The benefits of healthy soil include:
- Healthier plants in general
- Our fruit and vegetable plants are healthier, and they produce higher yields.
- Plants growing in healthy soil are less susceptible to insect and pest attacks.
- A healthy soil helps plants develop higher disease resistance.
- Healthier soil can hold more water.
- Another benefit of healthy soil is improved drainage.
- The addition of organic matter improves soil health through reduced compaction and improved airflow throughout the soil, but especially around the roots.
- At the surface, healthier soil is less prone to erosion.
- Because of healthy soil, plants are less susceptible to insect and pest attacks, and they are less likely to develop infections from diseases.
Organic vs. Non-Organic Soil
Organic soil is the end result of animal manure, compost, and plant decomposition. The process produces dirt that is full of minerals and microorganisms that help transform organic matter into a soil that feeds plants with its nutrients that they can become healthy, mature, and productive. It is, in essence, humus. This is what happens in natural habitats when plants drop leaves on the ground, twigs fall off trees, and other plant debris falls to the ground. The accumulation of these substances is leaf litter. In natural, undisturbed environments, the remains of deceased animals combine with leaf litter. And over time, it all decomposes, and the decay process produces an abundance of essential chemical elements. And the chemicals that are released during breakdown become nutrients that feed plants.
When different organic substances are combined, they undergo a similar decomposition process. And the end result of that produces a nutrient-rich, dark black crumbly material that is, in essence, humus.
Organic soil is always free from chemicals. It starts with a mixture of equal parts of clay, sand, and silt. However, the addition of organic matter gives it nutrients that are lacking in non-organic soil. Organic soil retains moisture, but it also drains well. Organic soil typically contains some of these types of organic matter:
- Bat droppings, which are known as guano.
- Blood Meal
- Bone Meal
- Fish Meal
- Mushroom compost – if available
- Seaweed – if available
- Soft rock phosphate
- Soybean meal
- Worm castings, which are what worms excrete as they eat decomposed organic matter.
The most common organic matter found in organic soil is compost, manure, and mulch. Additives such as worm castings and bat guano enrich the soil.
Non-organic soil mixes usually contain a combination of perlite – a product that is made from heated volcanic glass, expanded clay aggregate, and peat moss. Although these products are found in nature, soil companies process them to ensure that that they’re free of contaminants or toxins. They often add chemical fertilizers and products for disease, insect, and pest resistance. Non-organic soils lack organic matter so they won’t create ecosystems that promote healthier soil.
We are proud to feature a line of organic soil products because we believe that they are better for plants and the environment. We carry products from Malibu Compost, Foxfarm, and Edna’s Best from the E.B. Stone company. These are all California-based companies. Stop into one of our stores to see our extensive line of organic soil products and soil amendments.
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