Soil
Most of the soil found in a typical yard is not ideal for growing vegetables. It may have a lot of clay or sand in it. The lawn may also have had herbicides and pesticides applied. Non-organic fertilizers were most certainly used as well.
The soil that a local landscape supply yard has, is what they will usually call “screened topsoil.” This is not standardized and the quality and composition of it will very likely change with each load they get in.
Their source is usually from a construction site that is then screened to remove any rocks and other debris. In most cases it will be suitable for putting in a new lawn.
If you really need to purchase some soil, try to get it from a source that is certified. There are many places around the country that compost leaves and other yard waste from homes in many cities. Look for a certification of safety such as one from the US Composting Council Seal of Testing Assurance.
Garden Soil
What you want for your garden is a “garden soil” that is very high in organic matter to support plant growth. This organic material is humus and is often called “black gold” by gardeners and plant professionals. The Latin word for soil is humus.
It is a mixture of dead plant matter, animal matter and small particles of rock and other minerals.
If the area where you want to put your garden has a lot of clay or sand in it you can make it into "black gold" by adding lots of organic material to it. You may not be able to do it all at once. Eventually you will have a good humus that is rich in organic matter. The best source of organic material is from your own compost pile.
A very good indicator of good humus is the presence of earthworms. They play an important role in aerating the soil. A worm has no teeth, spine, bones, eyes, ears or lungs, yet as it burrows through the soil it creates tunnels to aerate the soil. At the same time the worm eats the dead organic matter and using its gizzard digests it and leaves behind a casting. Worm castings are really worm manure that aids in improving the tilth and friability. This gives it the fertility and a nice crumbly texture to support the root growth of plants.
The castings from a worm are very high in nutrients that are in a form that plants can take in and grow rapidly. Rototilling has been found to be detrimental to the soil by killing the earthworms, as well as disrupting the growth of beneficial fungi.
Over working or tilling damages the beneficial mycorrhizal fungi. These are beneficial fungi that have a symbiotic relationship with plants. Mycorrhizal comes from the Greek words “mykes” and “rhiza” which means fungus root.
Plants rely on these mycorrhizal fungi to convert the elements in the soil into nutrients the roots of the plants can take in to feed the plant. The plant and mycorrhizal relationship is a very complex one that enables the roots to take in the nitrogen, phosphorus and carbohydrates that are needed for the plant to grow.
The Smell of Rain
In addition to beneficial fungi there are beneficial bacteria to keep everything in balance. One type of bacteria called Streptomyces produces a chemical called geosmin when it dies. Geosmin is a compound responsible for the earthy taste and aroma found in beets and some freshwater fish such as carp and catfish. Humans are able to detect concentrations of geosmin as low 5-parts per trillion.
When we go for a walk in the woods after a rain, that wonderful earthy smell is now called petrichor, a word coined in 1964 by Isabel Bear and R.G. Thomas. It is most noticeable as the air becomes humid just before and during rainfall.
The ability to smell rain was very important for the survival of humans and animals.
Soil Test
It is a good idea to get a soil test if you are just starting a garden or if you want to grow something with a specific requirement of very acid or alkaline soil.
The pH is what regulates the amount of nutrients that is made available to the plants. Most plants will grow well with a pH between 6 to 7, but some will do better if it is below 6 and others will do better if it is above 7.
Some of the basic tests that can be done are the pH, organic matter percentage, phosphorous, nitrogen, potassium and calcium. Other tests for micronutrients are usually not needed for the home gardener.
A soil test should be done in the fall before the ground freezes. If there is something that needs to be done it will take some time for the results to occur. There are some do-it-yourself test kits available, but it is not likely that garden centers will have test kits at that time. You may find them online, but the most accurate and comprehensive soil tests can be done for a fee by your local Cooperative Extension or another certified soil test laboratory.
Garden soil should have 5% organic matter to be considered good. It is not unusual to find soil samples with less than 1% organic matter. If you have 10% organic matter you are very lucky or you have been following good gardening practices by adding compost to your soil.
There is a “Black Dirt” region of Orange County, NY which is 22-square miles in size that is famous for growing onions and other crops. It ranges from 30 to 50-percent and in places as high as 90-percent organic matter. As the glaciers receded 12,000-years-ago, swamps and bogs built up deep layers of decayed plant matter.
Fertilizers
Inorganic fertilizers are often too harsh and harmful to worms and all of the beneficial microbes that live in the soil.
To create a sustainable organic garden be sure to choose an organic fertilizer such as Espoma if they are needed.
The soil is a living ecosystem that works best if left undisturbed. Gently turning over your soil with a garden fork early in the spring, as soon as the soil can be worked, is all that is needed to blend in the organic matter.
If you see a lot of earthworms in your soil, that is a good indicator of having healthy fertile soil. Usually you will start to see them in warm, moist soil. There are about 30-species of earthworms found in the United States.
There are some that die when the ground freezes, but their eggs survive the winter and hatch when the ground warms up. Others such as the common night crawler burrow deep in the ground below the frost line, which might be more than 6-feet deep in the northern colder areas.
Soil Types
Soil that has a lot of sand in it will feel very grainy or gritty when you rub a sample between your fingers.
The most common form of sand is silica or silicon dioxide. It provides no nutrition in the form of trace minerals to your plants. It also does not retain water and dries out very quickly. Some plants such as cactus and some succulents will do well in this type of sandy soil. Most mixes for cactus plants will contain a high amount of sand to promote proper drainage.
Clay particles are very small. Silt is granular material of a size somewhere between sand and clay whose mineral origin is quartz and feldspar.
Soil that has a lot of clay in it will feel very smooth and slippery. Sand will feel gritty when rubbed between the fingers and silt, by comparison will feel like flour.
Most native soils are made up of sand, silt and clay. Sand particles are the largest and it will retain very little water since the water will drain from it very fast. Clay particles are very small and they pack so tightly together that clay soil retains too much water.
Loam is considered to be roughly equal parts of sand, silt and clay. Good garden soil needs to have some open space to hold and retain water and allow the plant roots to easily grow into. Sand has too much open space and the clay particles are packed too tightly together and do not have enough open space.
Organic matter is either living or formerly living material. Adding organic matter to your soil is the easiest and best way to improve your soil. Many soil tests show that the organic matter in the soil is 1% or less. Ideally a good garden soil should have 3% to 5% of organic material in it. Adding decomposed compost to your native soil is a good way to improve the friability of your soil.
Many of the essential nutrients your plants need can be provided by the sand, silt and clay in the loam. Compost does add a small amount of the essential nutrients in the form of minerals.
Fertilizers do not add a significant amount of the micronutrients your plants need. Plants also require some micronutrients such as: Boron (B), chlorine (Cl), chrome (Cr), cobalt (Co), copper (Cu), iron (Fe), manganese (Mn), molybdenum (Mo) and zinc (Zn).
Adding rock dust from granite or other rock mineral sources to your garden soil will provide the essential micronutrients your plants need. There are also many types of microorganisms in the soil that break down the minerals in the rock dust and convert the minerals into a soluble form that your plants can use.
Hardpan
Hardpan is a very dense type of soil made up of very small clay particles along with silica, iron oxides and calcium carbonate. This type is so very hard that plant roots and water cannot penetrate it. In many areas it is found below the surface soil. In the more arid desert areas it can be found on the surface.
This presents a challenge for gardeners, but it can be overcome by using thousands of years old Native American gardening methods in the very dry southwestern states. The Native Americans made a grid of square holes one to two feet square adjacent to each other, separated by a low berm around each from the hardpan they removed from the holes. This has the appearance of a waffle which is easy to visualize. With the soil in each hole loosened up to a depth of about one foot, some high organic containing humus and sand can be mixed in to make for good garden soil. The waffle garden can be thought of as a type of container garden that retains the water you give it.
If you have this type of very hard soil check with your local cooperative extension or the web for more detailed information.
Charles Darwin
Charles Darwin is most famous for his 1859 book “On the Origin of Species” but he devoted many years of his life studying worms and wrote a book about worm physiology and behavior. His 1881 book "The Formation of Vegetable Mould, through the Actions of Worms, with Observations on Their Habits" was his last book and sold many copies.
Here are some famous quotes:
”It may be doubted whether there are many other animals which have played so important a part in the history of the world as these lowly organized creatures. Without the work of this humble creature, who knows nothing of the benefits he confers upon mankind, agriculture, as we know it, would be very difficult, if not wholly impossible.” – Charles Darwin on earthworms, 1881
“Worms are the Intestines of the Earth” – Aristotle
Garden Spikes newsletters give you timely information once or twice a month. Subscribe Free to the Garden Times newsletter below.
Your email address will only be used to send you a newsletter and will never be sold. You can unsubscribe at any time.
