Photo by Pixabay/Khemanun Rugyooprasert
Most seasoned gardeners know that the secret to healthy, productive gardens is really no secret at all. It’s in the dirt, literally. Plants need moisture and sunlight to grow and, in the right amounts, they will flourish, but only if you start with good soil.
Like us, plants need food, in their case it is in the form of nutrients. Good soil provides these nutrients and also allows plants to take them up.
However, before knowing if your soil is healthy or not, you need to decide what type of soil you have. There are three main types, sandy, silty and clay. The particles that make up the soil are what are used to categorize each type by size. Sandy soil has the largest particles, clay the smallest and silty fits in the middle.
The combination of these three is what gives soil its texture. Sandy soil is easy to cultivate, drains more easily but requires more water since it doesn’t retain it. Silty soil has good water retention and circulation and is good for growing crops. Clay soil is easily compacted, is difficult to plant or even shovel because it clumps. Although it is hard to work with, it is able to hold roots better and has a more stable environment than the other two.
DIY Soil Testing
There is an easy DIY test to evaluate what type of soil you have. Dig down about six inches where you want to test. Fill a Mason jar about half full of the soil and then fill it to the shoulder with water. Set it aside to let the soil soak up the water.
Next, put the lid on and shake it for about three minutes. Set the jar down and leave for one minute. Then, measure the amount of sediment that has collected in the bottom. This is the amount of sand in the soil. Wait four more minutes and measure again. The difference between the two numbers in the amount of silt. After 24 hours, measure again. The difference between the second and third numbers will be the clay in the soil.
Calculate the different percentages of sand, silt and clay. The three numbers should equal 100 percent. Healthy soil is typically 20 percent clay, 40 percent silt and 40 percent sand. Results of this test will help you determine what to grow since different plants prefer different soil types. For example, silt and clay are hard to get wet but stay wet longer. Plants that like “wet feet” are happy here.
For the optimal garden, you can either choose plants accordingly or amend the soil type. For sandy soil, add humus, peat moss or aged manure. A warning about manure, it must be aged at least six months otherwise you run the risk of introducing new pathogens into your soil.
For silty soil, add coarse sand (not beach sand), gravel and compost or well-rotted horse manure with fresh straw. Coarse sand is also known as yellow or builder’s sand and is not as fine as beach sand nor does it contain salt like beach sand.
To amend clay soil, add coarse sand, compost or peat moss. This will make it a little easier to work with and the sand will create pockets of oxygen to help plant roots breathe.
When you know what soil type you have, you will next want to determine what the pH level is which, in turn, determines whether the soil is acidic or alkaline. There is also a simple test to determine this. Put two tablespoons of soil in a bowl. Add 1/2 cup vinegar to it, if it fizzes, it is alkaline. By the same token, put two tablespoons of soil in a bowl, moisten with distilled water and add 1/2 cup baking soda. If it fizzes, the soil is acidic. If it doesn’t react to either test, the soil has a neutral pH.
Either a high or low pH may result in plant nutrient deficiency or toxicity. When it is neutral, microbial activity is greatest and plant roots absorb nutrients best.
Once you know what you have, you can adjust the pH of the soil. Acidic or sour soil is adjusted by applying finely ground limestone and alkaline or sweet soil is treated with ground sulfur. Keep in mind, some plants prefer acidic soil or alkaline soil so treat your soil based on what you want to grow.
If you do a professional soil test, such as from the county extension office, the results will address the three elements of nitrogen, phosphorous and potassium. This is why fertilizers are blended with different percentages of these three elements, so they can be tailored for your soil type:
- Nitrogen, characterized by N in a blend, helps plants make leafy growth and gives plants their good green color. It is part of every protein in the plant so it is required for every process. Insufficient nitrogen is characterized by general yellowing of the plant. Ten pounds of blood meal has the same amount of nitrogen as 20 pounds of manure, minus the organic matter.
- Phosphorous, denoted by a P, is necessary for germination, strong root growth and producing flowers and fruit. It helps plants absorb minerals, grow strong stems and withstand disease. Bone meal is a good source.
- Potassium, known as K, regulates the water in plant cells and is necessary for flowering, fruiting, good root development and for plant stress tolerance. Weak stems and stunted growth are the results of lack of it. Wood ashes are a good source of potash, which is where the word potassium is derived from.
Potash is really various salts that contain potassium in water-soluble form. Before the industrial era, plant ashes were soaked in water in a pot, thus the name of pot ash. It was the main source of potassium.
One more sign of healthy soil is the presence of earthworms. If you dig up one cubic foot of soil, break it apart and find at least 10 earthworms, then the soil is healthy. They aerate the soil. If you have fewer, you can add organic matter like compost, aged manure and leaf mold. This organic matter slowly releases nutrients to promote microbial activity.
I never realized how widely different soils vary until I started putting a small garden out here at Ron’s. His soil is definitely clay whereas I have sandy soil. Mine is easy to dig and plant in; his not so much. I will never forget the first time I dug potatoes down at his place. At home, we pull up a vine and shake the soil off. I was literally shaking the vine to pieces and it wasn’t coming off. He watched me for a long time before he told me that it was not going to shake off any time soon!
There is not a bad nor a good type of soil, only different types. The secret is knowing how to make whichever kind you have the best it can be for the purpose you have in store for it.