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Once you’ve tested your soil and understand its needs, you’re better prepared to consider options to improve and safeguard your soil.

Organic Matter

Perhaps the most influential amendment you can add to your home garden soil is organic matter (plant and animal residues). The addition of organic matter will implement a plethora of improvements within the soil ecosystem and the overall environment:

Read more about soils in Introduction to Soils and Soil Science Fundamentals articles.

Compost

The source of organic matter is important—ask your supplier about its source materials and for test results that include info about nutrient content, pH, and salinity. While nutrient deficiencies can be treated with a fertilizer application, avoid any products with a high salt content, since it’s difficult to reduce soil salt levels. Consider the length of the composting process and if it reached the appropriate heat levels to break down the organic matter and kill weed seeds. Manure that hasn’t been composted long enough is likely to introduce viable weed seeds into your soils. When uncomposted plant matter, such as sawdust or wood chunks, is incorporated into the soil, it may rob plants of available soil nutrients because soil microbes are using these nutrients to break down the plant matter.

Creating your own compost is a great way to make your own organic matter, dispose of lawn and yard waste, and keep food scraps out of the landfill. There are many ways to construct a compost bin, and you can easily find premade systems online or at your local home and garden store.

Mulch

Mulch suppresses weed seed germination, regulates soil surface temperatures, decreases evaporation of soil moisture, and reduces soil compaction from foot traffic. Mulch created from organic matter will incorporate into the soil over time, providing nutrients for plants and beneficial soil organisms as it breaks down.

Leaves are free mulch! When cleaning up the yard in the fall, try a cut-and-leave approach, i.e. leaving behind some cuttings and plant debris on the soil surface. A layer of leaves on your garden soil inhibits weed growth, reduces soil erosion, provides habitat for beneficial insects during the winter, feeds for worms and other beneficial soil organisms, and improves the soil over time.

Drainage

Improving drainage helps water infiltrate soil, reduces runoff, and increases access to water for plants. Soil compaction is detrimental to both soil and plant health. In soils with poor drainage, compaction, or high clay content, you can improve drainage, though highly compacted soils can be difficult to remediate.

Adding organic matter should be your first endeavor, either by tilling it into the soil prior to a landscape renovation or by the annual application of a mulch, which soil microorganisms will incorporate into the soil over time.

Irrigation

Proper irrigation can help plants better withstand our hot summers. To encourage deeper rooting in the soil, irrigate less frequently but deeply. Soils with a high clay content, high compaction level, or on significant slopes require more time to absorb water than faster-draining soils, uncompacted soils, and locations with less dramatic topography. To maximize the amount of water absorbed by these soils, implement a cycle/soak process.

Cycle/soak is an irrigation system program that runs for shorter times each cycle but increases the number of cycles. For example, you could run a zone for 10–15 minutes per cycle and schedule it to run every hour for 3 or 4 hours during a single evening so that it receives a cumulative 45–60 minutes of water (depending on plant watering needs) over the course of that time. This is very different than watering 10–15 minutes of water each day, which moistens only the very top portion of the soil and inhibits deep root growth.

If you’re unsure of the coverage provided by your irrigation system, consider conducting a water audit. You can then improve the system to better cover dry spots or identify other plants that require less water. A free water check is provided by SLC Public Utilities.

pH Modification

To adjust a soil’s pH, incorporate amendments such as lime, aluminum sulfide, or sulfur. Aluminum sulfate and sulfur (sources of acidic ions, H+ and Al3+) lower the pH, making the soil more acidic. On the other hand, finely ground limestone (lime) introduces basic carbonate (CO32-) ions, increasing the pH or making the soil more alkaline. Since Utah’s soils are generally alkaline, sulfur or aluminum sulfate are typically recommended to lower the pH.

The addition of compost may provide some buffering for your soil’s pH, for example raising the pH of an acid soil or lowering the pH of an alkaline soil to reach a more neutral level. However, any change in soil pH will be minor and temporary, especially with the alkalinity of Utah’s water.

Fertilizers

Fertilizers are primarily comprised of the macronutrients, nitrogen, phosphorous, and potassium, with their relative percentages by weight denoted by the N-P-K ratio. For example, a 16-16-16 fertilizer would contain 16% each of the nutrients N-P-K. The remaining 52% would be comprised of filler materials and trace macro and micronutrients: sulfur, calcium, iron, manganese, copper, zinc, boron, and molybdenum. A fertilizer that contains some amount of N,P, and K is called a complete fertilizer, whereas a fertilizer that contains only one or two main nutrients is called an incomplete fertilizer, such as an 8-0-0.

There are three main types of fertilizers: mineral, industrial, and organic. Mineral fertilizers are made from naturally occurring minerals that are often obtained from mining. Industrial or synthetic fertilizers are made through an industrial process to create synthetic forms of nitrogen (e.g. ammonia, NH3). Organic fertilizers refer to animal manure, composts, and other natural materials.

Always read the directions and apply fertilizers, particularly synthetic, with care. When adding fertilizer, always follow the recommendations from your soil test or the product bag, and never over apply.

Applying excess fertilizer can have negative consequences for your own garden and the greater environment. For example, although plants require the nutrients contained in fertilizers, these nutrients are also salts. Excess soil salts can harm plants by triggering rapid growth that is weak and more susceptible to disease, and can cause scorch or burn. Excess fertilizer applications are easily carried off during surface water runoff events and can lead to excess algal growth or “algal blooms” and eutrophication that harms our rivers, lakes, and ultimately our oceans. In addition, soil microorganisms convert excess nitrogen in the soil into nitrous oxide (N2O), a powerful greenhouse gas.

One way to reduce potential pollutants in your local ecosystem is to fertilize with organic fertilizers such as compost, animal manure, bonemeal, bloodmeal, and fish emulsion. Organic fertilizers are not easily water soluble and so won’t end up in waterways in the same way synthetic fertilizers will. Organics also take more time to break down than synthetic fertilizers making it much harder to burn or otherwise toxify the plants in your home garden.

Crop Rotation and Cover Crops

Crop rotation involves rotating where you grow annuals and vegetables every season. Growing the same plants in the same place year after year will deplete the soil of the specific nutrients that those plants use. It can also increase the incidence of disease on the new year’s crop. By rotating where you plant certain crops year to year, you allow the soil time to replenish nutrients and reduce the likelihood of pests and diseases specific to those plants. If you leave an area fallow for a season, consider adding soil amendments, a layer of organic matter, or planting a nitrogen-fixing cover crop.

If a soil is deficient in nitrogen and will be left unplanted for one or more growing seasons, planting cover crops in the legume family (Fabaceae) is a great way to replenish soil nitrogen. Plants in the legume family (such as vetch, clover, alfalfa) are important players in soil and land rehabilitation because they can fix atmospheric nitrogen. More accurately, they house a beneficial soil bacteria known as Rhizobia within nodules attached to their roots which fixes atmospheric nitrogen into a form that the host plant can use. Rhizobia infect plant roots to initiate a symbiotic mutualism in which nitrogen is exchanged with the host plant in return for carbon. Later, as the roots of these legumes decay, they release nitrogen into the soil which will be available for the next crop of plants.

Gardeners can foster a healthy soil habitat with good soil management practices. In return, your soils will help produce a vibrant, vigorous garden.

Read more about soils in Introduction to Soils and Fundamental Soils articles.