Do It Yourself – Soil Analysis to boost your Garden’s Yield

Whether you’re a veteran gardener wanting to deepen your understanding of your garden beds or a newcomer curious about the potential of a newly prepared plot, there are numerous methods to test your soil.

Many of these tests are either free or come at a minimal cost, and even the most expensive option—a comprehensive lab soil analysis—is often quite affordable.

Begin with a straightforward assessment.

If you’re examining an existing garden plot, consider what has grown successfully there before. Have you faced unexplained issues with certain plants while others thrived?

If most of your gardening efforts have been successful, and you can attribute failures to factors like disease, insufficient sunlight, or inadequate watering, your soil is probably in good condition. However, if some or all plants consistently fail to grow or flourish, the soil might be the issue.

For a new garden bed, the previous vegetation offers clues about soil quality. If the area is lush with grass or other low-lying plants, the soil is likely fertile. If it was mostly barren with only a few robust plants, you might encounter some problems. Additionally, ensure that any potential garden spot gets plenty of sunlight.

Soil analysis – Drainage

soil analysis drainage

One crucial aspect of ideal garden soil is its ability to drain well. If the soil retains excessive water, plant roots can rot, leading to poor growth. Fortunately, a straightforward drainage test can reveal the soil’s drainage capacity.

Here’s how to perform the test: Select one or more low areas in your garden for testing. If your garden is entirely level, choose the center. Dig a hole that is 1 foot deep and 6 inches wide. Fill the hole with water and let it drain completely. After it has drained, fill the hole with water again. This time, measure how long it takes for the water to drain out of the saturated soil.

If the water drains within 4 hours, most vegetables should grow well. In cases of exceptionally well-drained soil, the water might disappear within minutes. On the other hand, poor drainage is typically found in soils with a high clay content and insufficient sand.

Soil analysis – Structure

Soil is composed of three primary components: clay, sand, and silt. When combined in the right proportions, these elements create loam, a rich, well-draining soil ideal for gardening. To quickly assess your soil structure, take a handful of moist (but not soaking wet) soil and squeeze it into a ball.

If the ball crumbles immediately when you open your hand, the soil is sandy. If it holds its shape even when poked, it contains a lot of clay. If the ball stays intact but crumbles easily when prodded, it is loamy, indicating a good mix of sand and clay suitable for gardening.

For a more detailed analysis of your soil’s composition, you can conduct a Mason jar test. This test requires a Mason jar with a lid. Start by collecting a soil sample, filling the jar one-third to halfway full. Scrape away the top inch of soil and take the sample from below this layer, removing any large rocks or organic matter such as roots. Next, fill the jar with water, leaving about half an inch to an inch of air space at the top. Some gardeners add a few drops of liquid dishwashing detergent to help separate the soil particles, though this step is optional. Secure the lid and shake the jar vigorously for at least two minutes, ensuring all contents are uniformly suspended.

After shaking, let the jar sit undisturbed. Sandy soils may settle within a few hours, whereas soils rich in clay and silt might take up to 48 hours to fully settle. The longer the jar sits, the more distinct the layers will become.

To interpret the results, measure the depth of each layer and calculate each as a percentage of the total soil depth. The bottom layer, composed of the heaviest particles, is sand. Above the sand is the silt layer, and the top layer consists of clay, the lightest component. Ideally, garden soil should be approximately 40 percent sand, 40 percent silt, and 20 percent clay.

Additionally, you might notice organic matter floating on the water’s surface, which could indicate acidic soil if it resembles peat. Alternatively, white crystals at the bottom of the jar suggest alkaline soil due to the presence of chalk.

With a shovel, trowel, Mason jar, and some time, you can conduct these tests to gather valuable information about your garden soil. While there are other tests that can provide further insights, they generally require more time and effort to complete.


Soil analysis – Acidity or Alkalinity

Knowing the pH of your garden soil—an indicator of its acidity or alkalinity—is essential. Most garden vegetables thrive in soil with pH levels between 5.5 and 7.5, with an ideal pH around 6.5. Outside these ranges, plants struggle to absorb nutrients effectively and may become more vulnerable to diseases. Testing soil pH is straightforward, but a reliable pH meter is necessary.

Garden centers often sell inexpensive test kits, typically priced between $5 and $10, which claim to measure pH. These kits usually involve scooping soil into a test chamber, adding water and an indicator solution, and comparing the resulting color to a chart. Similarly, for around $15 or more, you can buy pH probes that you insert into the soil to get a reading.

While paper pH test strips are also affordable and widely available, they can be difficult to interpret and may not provide precise measurements. Most home gardeners can generally tell if their soil’s pH is roughly correct or significantly off, but for accurate, narrow-range readings, a high-quality pH meter is necessary.

Thankfully, reasonably accurate pH meters are available starting at about $60. (While cheaper options exist, they may be unreliable.) A good pH meter should offer calibration with known solutions of pH 4 and pH 7 and should consistently give the same reading when measuring the same solution twice. A meter that fluctuates and provides inconsistent readings is ineffective.

A pH meter can also be used for more than just testing soil. It can determine the pH of foods for safe canning practices and assist home brewers and winemakers.

To measure soil pH, you only need a small sample. Remove the top layer of soil and collect a sample from the next 6 inches below the surface. Spread the sample on paper towels or newspaper and let it dry completely. Weigh a few ounces of the dried soil and an equal weight of distilled water (tap water won’t work). Mix the soil and water in a clean jar and shake well for a few minutes. Allow the mixture to sit for a couple of hours to settle. After calibrating your pH meter according to the manufacturer’s instructions, measure the pH of the liquid above the soil.

Alternatively, you can send a soil sample to a lab for pH testing and receive a comprehensive analysis of other soil characteristics.

Soil analysis – Nutrient Levels

soil analysis nutrient levels

Gardeners often need to know the nutrient levels in their soil to ensure healthy plant growth. While testing for all relevant elements at home is impractical unless you’re a chemist, it’s crucial to understand the levels of key macronutrients such as nitrogen, phosphorus, and potassium (the NPK in fertilizers), as well as calcium, magnesium, sulfur, and sodium.

Additionally, certain micronutrients like boron, manganese, iron, zinc, copper, and molybdenum may be essential for specific crops. Fortunately, several labs offer soil testing services that include these elements, along with pH testing.

You can find soil testing services through your county extension office, local universities, nurseries, and independent labs. An online search for “soil testing labs” will yield numerous options, including regional lab lists. Many lab websites detail the tests they perform and provide sample test result sheets. However, note that some labs cater primarily to farmers and may not process small numbers of samples, whereas university extensions typically do.

Soil testing is relatively inexpensive, with basic tests starting around $8 and comprehensive tests rarely exceeding $40 for the number of samples a gardener would need. Most labs will send you packaging materials and instructions for collecting your soil samples. After sending your samples back, you should receive your results in a short time frame. Be aware that labs experience a spring rush each year, so plan accordingly.

In even a small garden, nutrient levels can vary significantly from one area to another. Some gardening books recommend mixing several soil samples to create an average sample. However, this approach may not be practical as plants do not grow in an average soil environment. If you suspect variation in your soil, it’s better to test individual spots to understand the range of nutrient levels. You can then calculate an average if desired.

A thorough soil lab report provides not only nutrient concentrations but also analysis and recommendations. Most labs will indicate normal ranges for each nutrient, allowing you to compare your soil’s levels and identify deficiencies. Reviewing sample test sheets from various labs can help you choose one that provides the most useful and actionable results.

selfsb b4A last word

Among all assessments of soil composition, nutrient levels exhibit the swiftest fluctuations. Throughout the growing period, plants absorb abundant quantities of essential nutrients, rendering them detectable in the soil. Typically, this uptake is balanced by the gardener’s application of fertilizers both prior to planting and periodically during cultivation. Consequently, a soil analysis merely captures a momentary snapshot of a particular moment in time.

Engaging in soil analysis serves as an initial step. The subsequent endeavor involves enhancing the soil to foster optimal conditions for your crops. Often, solutions are outlined within the laboratory report, while local nurseries are well-equipped to navigate regional soil nuances. They can aid in deciphering the soil analysis and advising on suitable measures for cultivating healthier garden soil.

Additional resources:

A few compost recipes for all your gardening needs

If you see this plant in your backyard, don’t touch it!

Smart tips for gardening on dry soil

The #1 food of Americans during the Great Depression

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