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Practical Tips for Healthy Soil in a Home Garden

Learn what healthy soil is composed of and best practices for providing healthy soil for optimal plant growth.

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Updated:

February 28, 2022

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I'm a "soil first" gardener. I believe it is the most critical first step to creating and sustaining a healthy and productive garden. This article explains the basics of soil and offers practical tips for gardeners on ways to build and maintain healthy functioning garden soil.

Soil Basics

Some think of soil as simply the stuff that anchors plants into the ground. In actuality, soil is a lively interaction between structured solids (such as weathered rock minerals and decaying organic matter), living microorganisms and plant roots, as well as water, air, and nutrients.

Solid rock minerals play a large role in how soil functions. Soil is made of approximately 45% weathered mineral particles from the parent rocks of the area. You can discover your county's parent rock map and much more through a geology website from Pennsylvania Department of Conservation and Natural Resources.

A most obvious, basic characteristic of soil minerals is texture, which is determined by the size of the three mineral types it can contain. Sand is the largest-sized and coarsest mineral particle (0.05-2.0mm), silt is smaller (0.002-0.05mm), and clay is the smallest (<0.002 mm). Texture is not easily changed, since it is fixed by the locale's parent rocks. Soil texture influences how it functions. Small-sized particles like clay and silt hold water and nutrients and slow the breakdown of organic matter. Larger sand particles drain water quickly and provide better soil aeration. Home garden soils vary in the proportions of the three different textures. For example, loam contains equal parts of sand, silt, and clay, and is considered ideal for plant growth. Silty loam texture is a common Pennsylvania soil, in which silt predominates with sand and clay in lesser amounts. You can find the soil texture profile of your area at the United States Department of Agriculture's (USDA) National Resources Conservation Service's (NRCS) online Web Soil Survey (WSS).

Organic matter is largely made of carbon and is vital for healthy soil. Organic matter is mostly decaying dead plant residues and decomposed humus, but also includes living beneficial microorganisms and plant roots. Organic matter holds soil nutrients. As organic matter decays it slowly releases nutrients for use by plants. It also supplies food for living microorganisms in the soil. One of the most important characteristics/functions of organic matter is that it binds with mineral particles to create soil aggregates, called clusters. Open micro- and macro-pore spaces form around the clusters. The pore spaces are critical in that they hold water and transport air and dissolved nutrients through the plant root zone. They also allow space for fine roots.

Plants need nutrients for healthy growth and they obtain them from the environment, soil minerals and organic matter, and added fertilizer. (Note that addition of fertilizer should always be determined by a soil test.) Organic nutrients include carbon, hydrogen, and oxygen. These three are essential nutrients for plant growth and are found in the environment's air and water. Primary macronutrients obtained by plants from the soil are nitrogen (N), phosphorus (P) and potassium (K). Phosphorus and potassium are long-lived in the soil. Nitrogen leeches from the soil easily and often needs to be replenished. Fertilizers will provide the amount of these three nutrients as three numbers, such as 10-10-10 or 20-2-5. Secondary macronutrients found in soil minerals include calcium, magnesium, and sulfur. Additional nutrients, required but in small amounts (hence, they are called micronutrients) include iron, boron, zinc, copper, manganese, molybdenum, chlorine, and cobalt. Soil pH is a measure of acidity or alkalinity and affects the availability of nutrients to plants. Plants will show symptoms if there is an overabundance or deficiency in any of the macronutrients or micronutrients in soil or in their ability to absorb them. Conduct a soil test to determine the level of macronutrients in your soil and whether a fertilizer or pH adjustment is needed. Apply fertilizers based on soil test recommendations.

Soil is home to a large and diverse living community of beneficial microorganisms and insects. They contribute to soil health by maintaining a loose, aggregate soil structure, providing decomposing organic matter, recycling nutrients, and biologically suppressing plant pests.

Practical Tips for Healthy Soil

Soil health looks at how well a soil's make-up functions to support the growth and health of plants. These practical tips and gardening practices focus on the main properties of soil - physical, biological, and nutritive - that can be affected and are changeable. Gardeners can work to cultivate healthier soil in their home gardens.

1. Know the Look and Feel of Your Soil

Since 50% of soil is its physical structure, it is time well spent to feel your garden soil with your hands and to examine it thoughtfully. These field observations can help you determine the soil's texture, structure, and workability.

Feel the soil's texture by rubbing a small amount of soil between your fingers. Sandy soil feels coarse and gritty and falls apart easily when wet. Silt feels floury or silky when dry, yet slick and smooth when wet. Clay feels slick and sticky when moist and dries into hard clods often with cracks in the soil surface.

Dig up a sizable soil clump and examine it. Good soil structure feels crumbly or granular. It will have visible clumps. There may be loose pieces of soil with clinging plant roots and decaying organic matter.

Working your garden soil when it is too wet harms its structure. Take a handful of soil and press it tightly. Workable soil crumbles readily. Soil that is too wet stays as a compact mass, is sticky or muddy. It is not suitable for digging and planting. If the too-wet soil is mostly clay or silt, working it will cause it to crust and harden, further damaging its structure. Do not work soil that is too wet—it causes real damage!

2. Feed Your Soil with Organic Matter

Adequate organic matter is one of the most important indicators of soil health. Amending your soil with organic matter is easily done by just mixing it directly into the garden soil. Add organic matter when you make a new garden bed, expand an established bed and when you place new plantings. Dig-in or rototill 1 to 3 inches of organic matter into the top 6 to 12 inches of your garden bed and even deeper in a landscape bed. Fall is a good time to work in organic matter since it will spend the winter decomposing.

Commonly used organic soil amendments include

Shredded leaves
Home composting organic matter (see Home Composting: A Guide for Home Gardeners)
Compost from spent mushroom substrate (mushroom manure or mushroom soil)
Peat moss
Aged/dried animal manures
Humus

Organic matter characteristics differ. For example, aged composts and dried manures contain intrinsic nutrients, while peat moss does not. Peat moss holds more water than composts but has an acidic pH, however it is not proven that it lowers soil pH. Mushroom manure tends to be alkaline. Wood chips, sawdust and some animal manures may be considered too fresh. Using them as a soil amendment will tie up soil nitrogen as nitrogen is used heavily in the decomposition process. For very coarse tree bark/wood chips and sawdust, it is recommended these be composted one or two years before working into soil. When buying organic matter, always check the actual ingredients to know what is in the bag. If buying compost in bulk, be sure it was made following composting standards that include adequate temperature and time.

Garden soils with adequate organic matter tend to have a good open structure (be granular in appearance) and will be less compacted and more porous for plant roots. Organic matter keeps small particles like clay from forming a solid mass when wet or dry and also helps sandy soils hold nutrients and water. A Penn State soil test can, on request, measure the percentage of organic matter. When the results of the soil test report the relative cation exchange capacity (CEC) of less than 15, amend with at least 1 inch of organic matter.

3. Protect Your Soil with Organic Mulching

Mulches are applied as a uniform layer over the top of garden soil. When done correctly, mulching is a very beneficial garden practice. Organic mulches protect and improve garden soil through:
Retaining soil moisture by shading the soil from harsh sun
Moderating seasonal temperature extremes
Lessening weed germination and growth
Decomposing, thereby adding nutrients (organic matter!) and improving structure
Retaining rainwater and mild runoff

A variety of organic mulch materials exist for the home garden, including shredded bark or hardwood, shredded leaves, ½-inch screened compost, pine needles, pine bark nuggets, coarse wood chips and straw. An adequate and uniform depth of bark/hardwood or screened compost materials performs well. For more information on dyed mulch, see Mulch, A Survey of Available Options.

Mid-spring is a good time to mulch garden beds. Remove weeds and clean-up plant debris (add to your compost pile). Place a 2- to 4-inch uniform layer of organic matter on top of the garden soil. Take into consideration any remaining mulch from last season so as not to lay down too much. When mulching around a shrub or tree, keep all mulch 3 to 5 inches away from the base of its stems or trunk. Mulch touching the stems and trunks of trees and shrubs cause health problems and result in plant decline, or even death.

Synthetic (non-organic) mulches, like decorative stone, gravel, and landscape fabrics, are available. While they are long-lasting, synthetic mulches do not enhance soil quality like organic mulches do. Stones and gravel absorb heat, drying out soil and, thus, may harm beneficial the microorganisms living there. Air-borne weed seeds land between the stones and gravel and weeds sprout. Landscape fabrics serve as a barrier on top of garden soil but are problematic because they can limit activity of water and biological activity in the soil and degrade over time.

4. Avoid Soil Compaction - Tread and Till with Care

Soil compaction occurs with too much foot traffic, use of heavy equipment and other heavy loads, especially when the soil is wet or saturated. So, treat your garden soil carefully - walk on paths, keep garden carts on paths, and do not park or ride heavy vehicles on the lawn. Wait until garden soil is relatively dry in the spring before digging, planting, and stepping on it. Too much mechanical rototilling may also lead to compaction as soil aggregates are adversely affected. Newly-rototilled soil may look loose and friable, but if watered and stepped on during planting, the soil may readily compact and become firm. Compaction compresses soil's aggregate structure, reducing pore spacing. This leads to poor water infiltration, runoff, erosion, and ponding in your garden. Compacted soil may not be sufficient for plant roots to be able to grow, find water, air, and nutrients.

5. Be Fertile, Do A Soil Test!

Knowing about a soil's nutrients is to know about its fertility. A balance of available nutrients is essential for optimal plant growth. The only way to know for sure is to conduct a soil fertility test, available through your county Penn State Extension office. The soil test reports levels of the macronutrients phosphorus (P), potassium (K), calcium (Ca) and magnesium (Mg). It also makes a nitrogen (N) recommendation based on the intended crop. Soil pH, which affects the release of nutrients in the soil, and the soil's relative cation exchange capacity (CEC), which gauges soil nutrient holding capacity, are also reported. The percentage of organic matter is provided, on request. For any abnormal finding, a corrective recommendation is also provided. Recommendations typically note the need for lime, magnesium and/or a fertilizer containing nutrients, such as nitrogen (N), phosphorous (P) and potassium (K). Information on interpreting your soil test can be found in the Penn State article Interpreting Your Soil Test Reports.

6. Avoid, or Limit, Pesticide Use

Did you know that a well-tended garden rarely needs pesticides? It is normal to see insects on outdoor garden plants. Most do no or little damage. For most pests, a counterpart beneficial insect is looking to devour it. Healthy soil is normally teeming with a living community of beneficial microorganisms. Monitor your garden. If you see pest problem, take a thoughtful stepwise approach to determine whether a pesticide is necessary. Don't spray at the first sign of damage. Spraying pesticides needlessly can kill beneficial insects, including pollinators. Systemic pesticides taken up by plant roots and leaves can also hurt beneficial insects and other wildlife. Information on safeguarding habitat and encouraging pollinators can be found in the guidelines for Penn State's Pollinator-Friendly Garden Certification Program.

First, address other possible underlying causes of plant problems by implementing good gardening practices through

Maintaining healthy soil with compost and mulch
Selecting healthy (and even disease-resistant) plants and planting them in the right conditions
Removing diseased, decaying, and dead plants
Pulling weeds before they spread
Changing a gardening practice, eliminate overhead watering in favor or watering the soil

Second, if the damage due to an insect, consider non-chemical mechanical controls first. Set a trap, place screening, or hand-pick the pest.

Third, if a pesticide can't be avoided

Identify the specific insect
Always first consider options that are less toxic such as insecticidal soap or horticultural oil
Find a product that is labeled specifically for the pest
Read the pesticide product label. Use according to label instructions. More is not better.
Pay attention to and heed the product's environmental and safe use warnings