The BASICS: How to Test Your Garden Soil for Optimal Growing!

Gardening is therapeutic for many Americans. Besides, it gives them access to fresh and nutritious vegetables and other food crops. Unfortunately, not every American gardener has a flourishing garden. Some have given up gardening because of poor yield, pest infestation, or crop diseases. The reality is that soil health is a top determinant of how well your gardening goes. Some soils are acidic, while others are alkaline. The type of soil also varies from one garden to another. If you wish to have a successful home garden, you should understand your soil’s characteristics by testing it. Some tests can be done at home with or without special equipment, while others require laboratory services. This article will empower you on how to test your garden soil for optimal growth of your vegetables and other plants, and its importance.

Soil structure

Most people pay attention to soil texture and forget that soil structure [1] is equally important. Soil structure is how the particles group together into peds or aggregates. Peds are bound together by chemical, physical, or biological processes. This means that you can have two different samples of loam soil, but they behave differently because of the variance in structure. Freezing and thawing, for example, affect soil structure. Cultivation, compaction, excessive use of sodium, screening, cutting down vegetation, and excessive soil handling cause adverse effects on soil structure.

Usually, soil structure is classified by the shape, size, and strength of cohesion or grade of the peds. These factors determine pore size, airflow, and ease of root penetration. The main classifications of soil structure are:


This structure is very common, especially in the surface layers of soil. Soils with adequate organic matter normally have this structure. This structure is highly permeable.


The columnar structure is commonly seen in soils with excess amounts of sodium. The sodium destroys the structure and makes the soil too compact for water and airflow. The soil tends to look like a cluster of columns.


This structure is common in compacted soil. It has very little pore space, so its permeability is very low.

Simple Test to Determine Soil Structure

You can use this simple home test [2] to determine the structure of your soil.

  • Ensure your soil is not too wet or too dry. Dig a 6 to 10-inch deep hole.
  • Separate an intact section of the soil, the size of a beer can, and break it using your fingers.
  • As you break the soil, choose whether it feels granular, powdery, or cloddy. The soil should be made of crumbs of different sizes. The crumbs should hold shape if you slightly press them. Aggregates or peds that require a lot of pressure to break mean that your soil is too hard.

Fertile soil containing adequate amounts of organic matter tends to form round aggregates. As a result, it has high porosity that allows for free movement of oxygen and water.


Compaction happens when coil particles are pressed together. This reduces the space between pores. Usually, heavily compacted soil has a few large pores and is very dense. As a result, compacted soil has poor drainage and poor infiltration rate. The rate of gas exchange is also slow. Compaction increases soil strength, so it is harder for roots to penetrate this kind of soil. It is very easy to compact wet soil. If you use heavy equipment or tillage tools, especially when the soil is wet, you can destroy soil structure and increase compaction.

In a nutshell, soil compaction affects soil strength, pore space size, and pore distribution. You should conduct a soil compaction test because compacted soil reduces water availability and inhibits the growth of roots. It also stops earthworms and other important soil fauna from moving freely.

Soil Compaction Home Test

To conduct this test, take a piece of wire and plunge it vertically into the soil. Mark the point at which the wire bends. The wire will bend sooner for compacted soils than it will for less compacted soil. Ideally, you should get a foot of soil that is easy to penetrate. Repeat this simple test at different locations of your garden.


Soil workability means the desirability condition of the soil during tillage. Workable soil is that which can be tilled without structural damage. Workability is not entirely dependent on the soil itself. It is also affected by the tillage systems and the soil texture, bulk density, and water content. Workable soil allows water to reach the roots for proper plant growth. It is also less likely to be compacted.

Testing for Soil Workability at Home

Testing for soil workability should be done often because it is very easy. It should be done before planting. As you dig or till your land or garden and the soil produces plate-like clumps, it has poor workability. Most farmers measure workability by monitoring the amount of tractor fuel used to till the land.

Soil organisms

Soil organisms are a crucial part of global biodiversity. Their normal processes are important for soil health and fertility. There are numerous soil organisms, including macrofauna, megafauna, microfauna, mesofauna, and microflora. Human beings forget these organisms and their importance because they are normally hidden in the soil. A high population of bacteria, invertebrates, insects, and fungi in soil indicates its health. They keep the soil healthy by breaking down plant residue to release nutrients for other plants to grow.

Testing for Soil Organisms at Home

You can test for the presence of soil organisms by digging into the sand at least six inches deep. After doing this, observe the hole keenly for about four minutes. Note the different organisms you see and how many of each. You should have a notebook or recording material to note the soil beetles, centipedes, spiders, and others. You should remember that most soil organisms shy from light, so you should gently probe the soil to see more of them. Ideally, you should count at least 10 organisms. If you find less, your soil may not be very healthy.


Do you know the importance of earthworms in the soil? These organisms aerate the soil and infuse it with organic matter, bacteria, enzymes, and nutrients. They also enhance water infiltration and create a more stable soil structure.

Testing for Soil Earthworms at Home

Before conducting this test, ensure the soil is neither too dry nor too wet. You should also observe keenly to spot earthworm burrows and castings. Follow these simple steps to test for soil earthworms at home.

  • Dig out about six inches of soil.
  • Keenly observe the soil on the shovel and count the number of earthworms you see squirming around.
  • If you see three worms, the soil is good. If you see at least five, the soil is healthy and fertile. If you observe no earthworms, think of it as a sign that your soil lacks enough organic matter for the earthworms to feed on.

It is important to note that earthworms hate hot soil, so you may not find them in very hot areas.

Plant residue

Organic matter in the soil is fundamental. Organic materials and plants in your garden or farm can only decompose if microorganisms are present to break them down. If you notice signs of decomposition, you should be happy because it is a sign of soil fertility. Fast decomposition indicates good quality soil. If the decomposition is extremely slow, your soil may be poorly aerated. You should always check for plant residue a month after turning it into the soil.

If you had previously grown cover crops, chop them a month before the planting season. Dig up the garden or land a month after cutting down the cover crop about six inches deep to turn the plant residues into the soil. Observe the plant matter. If you notice plant fibers that you can recognize and dark-colored humus, the rate of decomposition is ideal.

Plant Vigor

This test should be conducted during the active planting and growing season. Plant vigor is a sign of good soil tilth and structure. It also indicates the soil has a diverse population and a well-regulated supply of water. Simply put, soil vigor refers to the ability of the seeds you sow to germinate into healthy seedlings very quickly in less than ideal situations. When checking for plant vigor, observe the plant color and size. The color and size should be relatively uniform. The overall growth of the seedlings should appear normal.

Root Development

The growth and development of roots are crucial for overall plant health. How the roots grow is an indicator of soil quality. Roots need water, air, biological activity, and crumbly soil to do their job. If the roots fail to grow well, plants will not thrive, and their production will be very low.

Testing for Root Development at Home

To do this test, you need a hand trowel or shovel. It is also important to have other gardening supplies at hand should you need them. Follow these simple steps:

  • Gently dig around one plant using the shovel or hand trowel.
  • Dig until you reach the root depth, then pull the plant up.
  • Check the size of the root, and look for white strands with a whitish healthy appearance. If the roots are brown and mushy, the soil has grave drainage problems. If they appear stranded, your plants may be infected by root-gnawing pests or disease.

Water infiltration

Good infiltration ensures the plant roots get water as needed. Soil with good infiltration allows for good airflow and prevents soil erosion and runoff.

Testing for Water Infiltration

Follow these steps to test your soil’s water infiltration rate:

  • Remove the bottom of an empty metallic can.
  • Push the can into the soil until you have about three inches of the can above the surface.
  • Fill the empty can space with water and mark the water height
  • .

  • Observe how long it takes for the soil to absorb the water.
  • Repeat the above steps severally until the water absorption rate slows down and the time of absorption becomes consistent. If the soil absorbs the water at a rate of below half to one inch per hour, your soil is compacted.

How to use a soil test kit

Soil testing should be a routine activity in your garden or farm. Regular soil testing alerts you about poor soil health and saves you from making losses after planting. In addition to the tests discussed above, you should buy a soil test kit. Kits are available online or in gardening centers. They are simple and fast to use, and they help you understand your soil’s chemical composition. For a healthy garden or farm, your soil needs specific nutrients that promote growth and production. The results obtained from a soil test kit help you know the amount of the essential nutrients and the types of fertilizers to use for healthier soil. Some of the essential nutrients measured by soil test kits are:


Nitrogen is the primary component of chlorophyll that plants use for photosynthesis, that is, the transformation of sunlight into energy. It also supports amino acids which are the building blocks of plants.


Phosphorus is vital for photosynthesis, cell growth, and energy storage. Without adequate amounts of phosphorus, plants do not mature properly.


This mineral regulates the movement of nutrients and water in plant tissues. It is also required for normal plant growth, and it regulates photosynthesis.

Soil pH

Soil test kits measure the alkalinity or acidity of the soil. Most plants thrive in soil with a neutral pH, between 6.5 and 7. There are exceptions that grow best in alkaline or acidic soils.

Types of Soil Test Kits

There are different types of soil test kits in the contemporary market. All of them are easy to use. These kits offer basic pH in-depth information about soil health. Below are the main classifications of soil test kits that you can find in present-day America.

Test Tube Chemical Kits

These kits allow you to conduct multiple tests. To use them, you simply add a soil sample, water, and powdered chemicals. You get color-coded results. It is important to note that some require you to prepare the solution 24 to 30 hours in advance.

Mail-In Kits

If you use this type of soil kit, you will be required to get soil samples, label them properly and send them to a lab. This option can be pricey, especially if you want to test several samples. The results of mail-in kits are usually more comprehensive than those from do-it-yourself soil kits.

Professional Chemical Kits

These kits can only be used by people with a basic understanding of soil science. The kits offer detailed and specific results. Usually, these tests are conducted by experts.

Digital Meters

Digital meters are very simple to use. All you have to do is stick the meter into the ground. The main limitation is that these sticks can only measure soil pH and water.


Testing your garden soil should be done periodically. The test results will help you remain aware of the health status of your soil. This information will guide you in choosing the fertilizers to use in your garden for healthy and productive plants. There are different home tests that you can do to determine the state of your soil. If they are inadequate, you can purchase home soil test kits or hire experts to conduct a thorough soil analysis.


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