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The Ultimate Guide to Soil Properties

A Comprehensive Look at Soil pH, Texture, Color, Nutrients, and More!

Good news! Tap Score’s Home Soil Test has arrived!

In our effort to inform you of the health of your everyday environment, we’re offering easy access to state-of-the-art soil testing for plant lovers, casual gardeners, and professional growers who want to maximize the full potential of their garden, potted plants, lawn, or farm. Not only does our new Home Soil Test tell you about the key indicators and nutrients in your soil, it also reports contaminants like lead and cadmium.

Not only can contaminants travel from your soil to your fruits and veggies, dust and dirt particles can travel into the air. Both of these means of exposure can negatively impact your health. If you have children who play in your yard, contaminated dirt can be a heightened concern.

To accompany your newest addition to the Tap Score family of environmental tests, the SimpleWater team of soil experts and horticulturalists has created an all-encompassing guide to soil properties you should know about. Take a look–you too can become an expert on all-things soil. While soil science is complex, a few basics can get you a long way to understanding your soil's health and what you can do to maximize it.

Jump to:

Soil pH Jump here.

Soil Texture and Porosity: Jump here.

Soil Structure: Jump here.

Soil Color: Jump here.

Soil Nutrients: Jump here

Photo by Zbynek Burival on Unsplash 

Soil pH:

Soil pH is a measurement of the acidity or alkalinity of soil. It is one of the most crucial indicators of whether or not your soil is suitable for growing plants. pH levels range between 0 and 14. 7 is neutral, lower numbers are increasingly acidic, and higher numbers are more alkaline.

Why is soil pH so important? 

When soil is either too acidic (generally below 5.0 for most plants) or too alkaline (usually above 7.5), crucial nutrients do not easily dissolve. Because plants take up these essential nutrients only after they dissolve in water within the soil, it is essential that these nutrients dissolve efficiently. If plants are either micro- and macronutrient deficient they struggle to grow and reproduce.

What’s the ideal soil pH?

Unfortunately, there is not a “one-size-fits-all” answer.  Soil pH can range quite a bit. It can be anywhere from about 3.0 (very acidic) to upwards of 9.0 (fairly basic). It varies according to a variety of factors including: geographical region, plant types, and rainfall.

In general, the optimal pH range for most plants is between 5.5 and 7.0. However, there are many exceptions. Additionally, a wide array plants are adapted to grow well in soil with pH values outside of this range.


Soil Texture and Porosity:

The texture of your soil plays an enormous role in its overall quality and health. The three main categories of soil textures are sand, silt, and clay. The distinction between each of these textures is determined by the dominant particle size. Each of these textures feel different to the touch, but the real important difference is the degree of drainage and aeration. Consequently, soil texture directly impacts the how well plant roots are able to grow...

Sandy Soils

  • Particle Size: <2 to 0.005 mm
  • Feel: Gritty when rubbed between your fingers
  • Pore Space Between Particles: Large
  • Drainage: HIgh
  • Why it matters to soil health: Due to the large pore space between soil particles, water drains quickly from sandy soils. As a result, sandy soils do not tend to get waterlogged, but can be susceptible to drought.
  • Silt Soils

  • Particle Size: 0.002 to 0.05 mm
  • Feel: Smooth when rubbed between your fingers. It often feels like flour when dry and slippery when wet
  • Pore Space Between Particles: Medium
  • Drainage: Moderate.
  • Why it matters to soil health: Silt’s water retention ability often leaves a sufficient amount of moisture for plant roots and nutrient dissolution. However, because silt is easily compacted, it can limit air circulation.
  • Clay Soils

  • Particle size: <0.002 mm
  • Feel: Sticky and mouldable when rubbed between your fingers
  • Pore Space Between Particles: Small. However, due to the small particle size, there are generally more total pores than sandy soil–leading to lower density.  
  • Drainage: Low.
  • Why it matters to soil health: Clay soils hold on to water due to their small pore size and tend to get waterlogged. However, if they do dry out, they become very hard and difficult to till.
  • Soil is almost always a mixture of the different texture types. As a result, the best soil type for your garden is a fine balancing act. While different plants thrive in varying soil textures ratios, the only guaranteed way to know what your soil is made up is to test it!

    Once you know the ratio of sand to silt to clay can you make necessary adjustments. Whether you need to water less frequently (to prevent water-logging) or add organic matter (to increase water-holding capacity), you can only improve the quality of your soil if you know what it’s made of, first!

    Soil Structure:

    Soil structure is directly determined by soil texture, as it refers to the way that sand, silt, and clay particles clump together (also known as aggregates). Soil structure is also influenced by organic matter and soil organisms (such as worms and bacteria). Good soil structure supports plant growth, regulates the movement of air and water, impacts root development, and contributes to nutrient availability..

    To check the quality of your soil structure, squeeze it. If the soil crumbles, it is likely to have fine aggregates and breaks up easily. Poor soil structure on the other hand, clumps together when squeezed. If you do find that you have less than desirable soil, fear not! Adding organic matter can often solve the problem–as it increases pore space (and therefore aeration) and improves drainage.

    Photo by Antonio Jordán via Imaggeo.

    Soil Color:

    If you assume that all soil is some drab shade of brown, we’re here to surprise you. Soil can range from red to purple and even white. Soil can vary so widely in color that soil scientists have created a categorization system called the Munsell System of Color Notation. The system assigns color using three components to categorize soil:

  • Hue: The specific color
  • Value: Lightness and darkness
  • Chroma: The color intensity
  • Analogous to the way paint stores have pages of color chips, the Munsell System consists of a system of color chips based on these three components. Soil can be visually matched to a chip and then assigned a corresponding Munsell value.

    Photo via Munsell Color

    A soil’s color can indicate various chemical processes that occur with the soil– such as weathering of geologic material, the chemical reactions of different minerals in the soil (especially iron and manganese), and the decomposition of organic matter. Climate, geography, and geology impact the speed and conditions under which these factors occur–and therefore play an important role in determining soil color.

    What does your soil color tell you about your soil quality?

  • Dark or black soil  indicates a high concentration of organic matter–which in turn indicates increased soil fertility.
  • Light-brown or yellowish-brown soils indicate that soil is well-aerated and is a good environment for plant roots.
  • Red or reddish-brown soil is most often caused by elevated iron content. These soils tend to be well-aerated. Most red soils tend to be strongly weathered, increasingly acidic, and less fertile than browner soils.
  • Gray soils indicate chemical reduction of iron and/or manganese due to water-logging, as well as lack of oxygen. As a result, gray soil indicates a poor plant-growing environment (due to poor drainage capacity).

  • Photo by Neslihan Gunaydin on Unsplash

    Soil Nutrients:

    Plants require sixteen elements in varying amounts to ensure healthy growth, development, reproduction, and disease-tolerance. These essential elements can be categorized into Primary Macronutrients, Secondary Macronutrients, and Micronutrients. .

    Primary Macronutrients are obtained from the surrounding, water, and soil around the plant. Oxygen, carbon and hydrogen are among the macronutrients that are naturally abundant. Secondary Macronutrients are available to the plant via uptake from the soil. Micronutrients, which are needed in trace amounts, are obtained from the soil.

    These 16 key nutrients play a different role in plant health and a deficiency in any one can negatively impact plant growth and development. For example, if soil is low in phosphorus plants can exhibit stunted growth, thin stems, and abnormally dark leaves.

    On the other end of that spectrum, excess levels of many of these nutrients can lead to harmful toxicity. For instance, excess boron can inhibit seed germination and therefore can reduce plant’s ability to reproduce

    How do I know if my soil is healthy?

    Given that each of these nutrients plays a crucial role in the health of your soil and plants, wouldn’t you like to know if they are all present in sufficient amounts?

    While you can visually diagnose your soil’s texture, structure, and color, critical elements for soil health like pH and nutrient balance require that you test your soil. It’s the only guaranteed way to know what’s happening below the surface.

    Want more soil info? Send us an email at hello@simplewater.us and our team of scientists, horticulturalists, and plant lovers will give you the scoop on soil!

    It's hard to get trustworthy advice when it comes to your drinking water, so we made Tips for Taps to help answer your questions. Order a Tap Score Water Test and receive personalized support from professional engineers and scientists by phone, email and chat.