SOIL
The single most important thing to a garden is what is below the surface of the ground. But soil may be the thing least understood by the urban gardener. Soil is made up of varying sizes of mineral and organic particles mixed with quantities of air and water. The mineral elements come from weathered rocks from the earth’s surface, the organic matter from decayed plant and animals. Soil normally refers to what is naturally found at the surface and is what is usually used by the urban gardener as the growing medium.
Soil Texture: The size of the mineral particles in soil creates its texture and defines its type. The three basic types of particles (in order of increasing size) are CLAY, SILT and SAND.
CLAY is the smallest soil element. Typically particles are so small that most of them are not visible under a microscope. CLAY can be rolled into long "worms" if moistened and rolled in your hand. Clay particles have a tendency to pack together becoming very dense, shutting out water and air especially if the particles are plate-like and more horizontal in structure. This type clay creates compacted hardpan hostile to root growth. This type clay is typical in the vicinity of the Haws Haven Experimental Farm and is what we call "caliche".
SILT is minerals in size between that of clay and sand.
SAND is the largest particle size. Moisten the soil and rub some between your thumb and fingers. Sand is harsh and gritty and will scarcely hold together. Clay can be squeezed into a firm shape. Silt can be somewhat gritty, but will more or less hold together when moist. A 100% SAND soil allows for air to penetrate, but has poor water retention qualities.
LOAM is the term for a soil that is approximately 10 to 20 percent clay, 25 to 70 percent silt and 20 to 65 percent sand. Soils with this type structure are best for a garden especially if it contains substantial amounts of humus (partly decomposed organic material).
DETERMINE SOIL TYPE Fill a quart jar about 2/3 full of water. Add a tablespoon of powdered laundry detergent as a dispersing agent to break up the chunks. Obtain a sample of soil from the area of the root zone by discarding the top two inches and taking the sample from 2 to 8 inches down. Break up the soil as best you can and leave on a clean surface in the sun to dry thoroughly. Add soil to the jar, screw on the lid and shake it vigorously. Then let the soil settle. The heaviest sand particles sink to the bottom in a few seconds. The silt layer takes a few minutes and the clay particles may not settle out over several days or even weeks. Measure the settled out layers to get a fairly accurate estimate of the texture composition.
HHEF Soil Test: July 2009
Sample of dirt; crushed; dried; filled gallon jar 2/3 full with water; 1 tablespoon of laundry detergent; added soil until jar full; let set for two days. The soil settled out into three barely visible different size particles. However, there wasn’t a marked difference in the soil texture. When damp, all three layers form “worms” by rolling in your hand.
The soil in the Haws Haven Experimental Farm is very heavy clay with a lot of caliche. When the soil dries out it is VERY hard—like a brick. It is great for making adobe bricks, but not suitable for a great garden. It does not drain well, which is a very important soil characteristic nor does it naturally have nutrient value just by itself. When I first started gardening, I took my shovel, dug one shovel depth, put it to the side and went down one more shovel depth putting the soil on top of the previously dug out soil. The idea was that I was loosening the dirt. Then I would put the rototiller to it. It did leave a very nice consistency of loose dirt for planting. However, I noticed that over time the soil became even more compacted than before and still had poor drainage. These clayey characteristics don’t go away if you put the native soil in a raised grow box.
HHEF seeks to improve the soil by adding sand to decrease the over all percentage of clay and primarily by adding compost and manure. Compost and manure increases the porosity of the soil and add beneficial bacteria and microbes to the soil. The bacteria and microbes tend to make more of the chemicals needed for plant growth available for use by the plant.
The single most important thing to a garden is what is below the surface of the ground. But soil may be the thing least understood by the urban gardener. Soil is made up of varying sizes of mineral and organic particles mixed with quantities of air and water. The mineral elements come from weathered rocks from the earth’s surface, the organic matter from decayed plant and animals. Soil normally refers to what is naturally found at the surface and is what is usually used by the urban gardener as the growing medium.
Soil Texture: The size of the mineral particles in soil creates its texture and defines its type. The three basic types of particles (in order of increasing size) are CLAY, SILT and SAND.
CLAY is the smallest soil element. Typically particles are so small that most of them are not visible under a microscope. CLAY can be rolled into long "worms" if moistened and rolled in your hand. Clay particles have a tendency to pack together becoming very dense, shutting out water and air especially if the particles are plate-like and more horizontal in structure. This type clay creates compacted hardpan hostile to root growth. This type clay is typical in the vicinity of the Haws Haven Experimental Farm and is what we call "caliche".
SILT is minerals in size between that of clay and sand.
SAND is the largest particle size. Moisten the soil and rub some between your thumb and fingers. Sand is harsh and gritty and will scarcely hold together. Clay can be squeezed into a firm shape. Silt can be somewhat gritty, but will more or less hold together when moist. A 100% SAND soil allows for air to penetrate, but has poor water retention qualities.
LOAM is the term for a soil that is approximately 10 to 20 percent clay, 25 to 70 percent silt and 20 to 65 percent sand. Soils with this type structure are best for a garden especially if it contains substantial amounts of humus (partly decomposed organic material).
DETERMINE SOIL TYPE Fill a quart jar about 2/3 full of water. Add a tablespoon of powdered laundry detergent as a dispersing agent to break up the chunks. Obtain a sample of soil from the area of the root zone by discarding the top two inches and taking the sample from 2 to 8 inches down. Break up the soil as best you can and leave on a clean surface in the sun to dry thoroughly. Add soil to the jar, screw on the lid and shake it vigorously. Then let the soil settle. The heaviest sand particles sink to the bottom in a few seconds. The silt layer takes a few minutes and the clay particles may not settle out over several days or even weeks. Measure the settled out layers to get a fairly accurate estimate of the texture composition.
HHEF Soil Test: July 2009
Sample of dirt; crushed; dried; filled gallon jar 2/3 full with water; 1 tablespoon of laundry detergent; added soil until jar full; let set for two days. The soil settled out into three barely visible different size particles. However, there wasn’t a marked difference in the soil texture. When damp, all three layers form “worms” by rolling in your hand.
The soil in the Haws Haven Experimental Farm is very heavy clay with a lot of caliche. When the soil dries out it is VERY hard—like a brick. It is great for making adobe bricks, but not suitable for a great garden. It does not drain well, which is a very important soil characteristic nor does it naturally have nutrient value just by itself. When I first started gardening, I took my shovel, dug one shovel depth, put it to the side and went down one more shovel depth putting the soil on top of the previously dug out soil. The idea was that I was loosening the dirt. Then I would put the rototiller to it. It did leave a very nice consistency of loose dirt for planting. However, I noticed that over time the soil became even more compacted than before and still had poor drainage. These clayey characteristics don’t go away if you put the native soil in a raised grow box.
HHEF seeks to improve the soil by adding sand to decrease the over all percentage of clay and primarily by adding compost and manure. Compost and manure increases the porosity of the soil and add beneficial bacteria and microbes to the soil. The bacteria and microbes tend to make more of the chemicals needed for plant growth available for use by the plant.
You gave a formula of 75% sawdust and 25% sand as a custom soil. Are you mixing that with your native clayey soil? If so, what amounts of each? Or are you removing the existing and replacing it with your formula? What kind of wood? Some are more acidic/nutrient than others.
ReplyDeleteI realize that every region and piece of land has its own soil characteristics. So, I'm not asking for a universal (one size fits all) formula, but my ground is very clayey too. Red clay instead of brown/dark like yours. I'd like to participate in your experiments. Any thoughts?
The mixture of 75% sawdust and 25% sand is the typical formula for the Mittlieder method. I tried this method and add great success, but I don't do it any more because 1. Sawdust is not readily available; I became concerned about glues and other chemicals in the sawdust and 2. This method requires regular feeding of commercial fertilizers to overcome the effects of the decaying sawdust. Over all it turned out to be an expensive way to garden. I am all for saving money. That is my opinion anyway.
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