Topsoil is a key component used to provide nutrients to plants. However, its availability and cost can make it difficult for gardeners to acquire. For this reason, it is often recommended that gardeners preserve what is left of topsoil after a gardening season ends. To ensure enough healthy topsoil is ready for the next planting season, either store the remaining topsoil or take measures to ensure it stays healthy between gardening periods.
How do gardeners store and preserve topsoil for the long-term? Preserving topsoil is done by maintaining its pH, organic matter, and nutrient content levels by doing the following:
- Avoid Disturbing the Soil
- Reduce the Use of Soluble Fertilizers
- Use Pesticide Alternatives
- Prevent Compaction
- Rotate Crops
- Use Cover Crops
Whether preparing topsoil for gardening or preserving existing topsoil before the next growing season, the following tips can help gardeners understand this delicate piece of mother nature and how to keep it safe and sound. Read on to learn how to preserve topsoil for the long-term, the importance of topsoil for plant growth, and bonus tips for maintaining mulch and compost.
How to Store and Preserve Topsoil Long-Term
Topsoil is the soil found on the surface of a garden plot, as explained by Michigan State University’s article, “The Shocking Truth About Topsoil.” It can span from two to ten inches in thickness, depending on the region.
Topsoil functions similarly to the soil layers underneath it. However, the following are some of the ways it can benefit plants:
- It provides a natural habitat for plant-friendly microorganisms.
- It helps recycle waste products from organisms to offer plants organic nutrients.
- It filters water for plants to absorb.
Storing topsoil alone is not adequate to keep it healthy enough to use in the next planting season. Although storing it is necessary between gardening seasons, it is equally critical to maintain the topsoil, even if it is “put away.”
The best way to ensure that the topsoil stays healthy over a long period is to maintain its pH levels, preserve organic matter, and manage its nutrient contents. The following tips can help keep topsoil in tip-top shape for future planting.
Maintaining pH Levels
By keeping the pH level of topsoil appropriate for the crops that will be growing, a sufficient amount of nutrients will be available to support the plants. A well-maintained pH level will also prevent toxicity.
Preserving Organic Matter
“Managing Soil Health: Concepts and Practices,” published by PennState Extension, explains that, to maintain healthy levels of organic matter in topsoil over the long-term, more organic matter must be added to compensate for losses from decomposition. Gardeners can do this in multiple ways:
- Add remaining residue from healthy crops. Healthy crops are an excellent source of organic matter. Any residue left from them after the season ends should be added back to the soil.
- Plant cover or perennial crops. Cover crops such as grasses and wheat and perennials like legumes act as a living mulch for both topsoil and future plants.
- Add animal manure or compost. Manure or compost can attract plant-friendly microorganisms that generate more organic matter.
Maintaining Nutrient Content
Knowing the best times to add manure, compost, or other fertilizers and the amount to add will ensure topsoil stays full of the nutrients it needs to support plant growth. For example, organisms such as earthworms thrive with proper calcium levels and improve the topsoil’s aggregation as a result.
Managing Nitrogen Levels
Nitrogen tends to experience leach losses in soil because the negative charge of the molecule is not held in soil particles. Nitrogen leaching is most likely to occur during the fall, winter and early spring. Because of this, gardeners are encouraged to monitor and manage their soil’s nitrogen levels at these times of the year, especially during storage or if there are no crops planted.
The following are a few things to look out for to ensure soil has minimal nitrogen leaching:
- Urea-containing fertilizers and manure with nitrogen can lose effectiveness when not incorporated into the soil. If they are not stored correctly and are unused after long periods, they eventually lose their nitrogen potency.
- Warm, poorly aerated soil can quickly lose nitrogen from microorganisms converting the nutrient to nitrous oxide and nitric oxide gases.
Managing Phosphorus Levels
To maintain healthy phosphorus levels, ensure the following:
- Keep an eye on the levels of organic matter in the topsoil. Adding organic matter increases the availability of phosphorus. For example, mycorrhizal fungi help plant roots gain access to phosphorus and other nutrients.
- Be mindful of the amount of manure and fertilizer added to the topsoil. An excess amount can lead to too much phosphorus.
- Practice preventive methods to reduce soil erosion.
When maintaining the nutrient content of soil, make sure to supply it with a diverse mix of nutrient sources. Only using compost or manure, for example, may help provide the soil and plants with nitrogen, but it can also lead to an excessive amount of phosphorus.
Combining a blend of manure or compost with cover crops or other forage can give soil the balanced set of nutrients it needs without leading to excess.
Do not lay up for yourselves treasures on earth, where moth and rust destroy and where thieves break in and steal, but lay up for yourselves treasures in heaven, where neither moth nor rust destroys and where thieves do not break in and steal. For where your treasure is, there your heart will be also.Matthew 6:19-21
Tips to Keep Topsoil Healthy
The following are additional ways to ensure topsoil remains healthy in between growing seasons:
Avoid Tilling or Disturbing the Soil
Excessive tilling can harm topsoil and the layers of soil underneath. For one, the act of tilling increases the levels of oxygen in the soil, which leads to the stimulation of microbial activity, which aids in the decomposition of organic matter.
Tillage also interrupts soil aggregates, which can expose organic matter particles to microbials.
Avoid disturbing the soil as much as possible to prevent damage.
Reduce or Eliminate the Use of Soluble Fertilizers
In general, overfertilizing crops can make them more susceptible to pest problems. Furthermore, soluble fertilizers can decrease a plant’s pest resistance, leading to higher pest density and crop damage.
Use Pesticide Alternatives
Although it may be tempting to use pesticides to get rid of harmful insects fast, it can end up hurting the plant, soil and beneficial organisms instead.
Rather than use a pesticide, try to create an environment that is healthy enough for beneficial organisms to thrive and control pest populations.
This concept is known as farmscaping, or the “ecological approach to increase and manage biodiversity with the goal of increasing the presence of beneficial organisms,” according to Penn State University.
Most farmscaping methods include using insectary plants, hedgerows, cover crops, and water reservoirs to create habitats for beneficial organisms such as:
- Birds that prey on pests or parasites
Although farmscaping is primarily used to eliminate harmful pests, it simultaneously stabilizes soil and prevents water runoff while adding organic matter.
Soil compaction occurs whenever soil undergoes a high amount of foot and equipment traffic while it is wet. Frequent traffic begins to compress the soil, which reduces pore space and increases bulk density.
The results of soil compaction and limited pore space include:
- Poor water filtration and drainage with an increased rate of runoff.
- Soil hardness, which makes it difficult for plant roots to anchor and grow.
- Makes the topsoil habitat less ideal for microorganisms that are too small to move soil particles and are therefore restricted in movement.
Reduce compaction by limiting the use of heavy machinery, such as tractors, on top of the soil when possible. It is also recommended to plant cover crops with taproots that can infiltrate the topsoil and create macropores to alleviate compaction.
Regular, diverse crop rotations between gardening seasons will disrupt soilborne pest and disease life cycles, which will significantly improve crop health. Rotating crops will also help manage weed growth and reduce excess nutrients.
Use Cover Crops
Cover crops are beneficial because planting them in between gardening seasons is one of the most helpful things gardeners can do to preserve topsoil.
Cover crops can help maintain and increase organic matter levels. Besides, specific varieties of cover crops have taproots that help create larger pores in the soil, reducing the risk of compaction.
Cover crops offer many more benefits for both soil and future plants:
- Cover crops can help reduce the amount of soil erosion that takes place in between gardening seasons.
- The biomass that comes from cover crops usually returns to the soil, which increases levels of organic matter.
- Fibrous-rooted cover crops promote aggregation and stabilization of the soil.
- Cover crops that attract mycorrhizal fungi can significantly benefit future plants.
- Add more nitrogen to the soil by adding legume cover crops, which promote nitrogen fixation.
- Finally, cover crops that nitrogen and other essential plant nutrients that can dissipate over time are recommended.
Factors that Influence Topsoil Quality
“Topsoil Quality Guidelines for Landscaping,” by Rich Koenig and Von Isaman, explains that there are many factors that determine a topsoil’s quality, including:
- Soluble Salts – Topsoils high in soluble salts make it difficult for plants to absorb water efficiently.
- pH – A pH level of 7 is neutral; measurements above 7 mean that the topsoil is alkaline, or basic, while numbers below 7 indicate that the soil is acidic. Different plants thrive in various pH levels of soil, so it is important to make sure the topsoil is at a pH level suitable for the plants in the garden.
- Texture – Texture refers to the percentage of sand, silt, and clay-sized particles within the topsoil. It can influence how well the soil can hold water and nutrients, aerate and drain. Ideally, topsoil should have a balanced mix of sand, silt, and clay.
- Organic Matter – The organic matter in topsoil can help a plant retain nutrients. Topsoil is usually darker than the soil layers underneath because of the organic matter it contains; high organic matter usually means the soil quality is better, although this does not necessarily imply darker topsoil is better.
- Coarse Fragments – A large percentage of coarse fragments, such as gravel and rocks, in topsoil can make it difficult for gardeners to seed new plants. Rough pieces can also make it challenging for the soil to aerate and manage overall.
- Nutrient Content – Nutrients are essential to plant growth. Quality topsoils should have adequate levels of phosphorus, potassium, nitrogen and iron.
- Sodium-Absorption Ratio (SAR) – The sodium-absorption ratio (SAR) is the measure of the amount of sodium to calcium and magnesium in the soil. Soils with higher SAR values tend to have a weak structure as well as low water infiltration and percolation rates.
Clearly, topsoil that does not have the appropriate levels of each of the above factors will not be able to provide a plant the support it needs.
Why Should Gardeners Store Topsoil?
It may seem odd to put away soil after a gardening season, but there are many reasons why it is critical to do so:
The Importance of Topsoil
Topsoil is crucial because it provides many of the nutrients that a plant needs to grow. It also helps sustain plants with food and energy and helps to anchor them in place.
Topsoil is a Limited Natural Occurrence
Believe it or not, quality topsoil is hard to come by. In fact, according to Columbia University, “it can take 500 to 1,000 years for one inch of topsoil to form through the interaction of bedrock, climate, topography, and living organisms.” That equals only one millimeter of topsoil for every two-and-a-half acres of land!
Topsoil Erodes Easily
Erosion is a geological process that involves the gradual wearing away of soil, rocks, or other hard, earthy substance by wind, water, ice and other natural agents.
All these different types of natural forces–especially wind and rain–can slowly move pieces of soil away from the garden, especially when it is unprotected from these elements.
This slow process can be challenging to observe, especially if the topsoil’s earthworms, fungi, and other decomposing organic matter cannot rebuild the soil quickly enough, as discussed in “Protecting Your Topsoil from Erosion.”
In many cases–especially when humans are involved in the erosion process–the rate of soil erosion becomes faster than the speed these organisms can regenerate. The rate of soil erosion has surpassed the rate of soil formation since the 19th century, leading topsoil to become a threatened natural resource.
Preparing Topsoil for Storage
Regular potting soil that functions as a substrate can easily be stored in large, clean, protective containers that are free of moisture. The container, in turn, can then be placed in a dry area like the garage or gardening shed.
However, topsoil is much different than potting soil because it contains living organisms; therefore, topsoil requires a unique, more delicate storing process.
Those who are going to store topsoil will have to start with where the soil is being kept. Where the soil is located will affect how it will need to be stored.
There are two places where topsoil can be found and is often kept: as a large pile outside of the garden bed or placed on top of the garden bed.
Gardeners who are renewing their garden beds usually have topsoil initially set aside, while those with existing gardens have topsoil already spread out.
- Set-Aside Topsoil – Before purchasing or having topsoil delivered to your home, the area it is being deposited must be first prepared, especially when waiting a while before using it in the garden. First, make sure the area is free of possible contaminants and debris, such as wood, concrete or bricks. Also, if there are any weeds present, make sure they are removed or controlled.
- Garden Bed Topsoil – For topsoil already spread in garden beds, it is best to plant cover crops in between gardening seasons to prevent erosion and ensure the soil retains its nutrients, and microorganisms stay happy.
Before storing any topsoil, make sure to perform a soil test to assess its current health before going into storage. This way, it is possible to continue maintaining the soil’s different levels (pH, organic matter, nutrients, etc.) throughout its storage period.
When it comes to storing organic materials such as topsoil, the key is to slow down the growth of fungus, decay, and rot, and to prevent nutrients from escaping. Although a gardener’s first instinct may be to store topsoil in a sealed container, it is stored best right where it belongs–on the ground!
The following are tips for storing topsoil that has been set aside for later seasons or currently rests in the garden itself:
Storing Set-Aside Topsoil
For gardeners who have a large pile of topsoil set aside to add to a new garden later, it is best to use wall storage or loosely cover the soil with a tarp or burlap material. Use stakes to keep the tarp in place and prevent it from blowing away.
However, when covering topsoil, make sure that the material does not smother the soil. It still needs proper aeration for essential living microorganisms and organic matter to survive.
Storing Garden Bed Topsoil
The process for storing topsoil that is already spread across the ground in the garden will look a little different. Rather than keeping it contained or covered with a tarp, it is best to leave the soil as it is on the ground.
To prevent natural erosion from rain, wind, and other elements, especially for the long-term, plant a cover crop (such as grass) to ensure the soil also maintains a healthy pH and nutrient level in addition to microorganisms and organic matter.
Candide recommends that gardeners continue using organic matter such as mulch or compost to the surface to feed microorganisms present in the topsoil and provide moisture.
Long-Term vs. Short-Term Storage
Greener Horizon explains that another factor to consider when beginning to store topsoil is the duration of which it will be saved:
- Short-Term Storage – Short-term storage is ideal for gardeners who are planning to cultivate a new garden within one to three weeks. Outside of extreme weather conditions, such as heavy rain, gardeners should see no problem with leaving the topsoil exposed in either a pile or in the garden bed, but otherwise, it may be necessary to store or briefly cover topsoil for immediate projects.
- Medium-Term Storage – For those who are expecting to get lots of rain or do not plan on planting again for one to two months, a medium storage duration can work. Use a light tarp to cover topsoil and use stakes to keep the tarp in place. Make sure that the tarp fits loosely over the soil to allow airflow.
- Long-Term Storage – Long-term storage is usually recommended for gardeners who want to save topsoil for another season (three or more months away). In this case, it is important to make sure that soil is in an area that is free from ground moisture, like running rainwater. Either use wall storage with a tarp for piles of topsoil, or an elevated garden bed with a tarp.
Topsoil is unlike regular potting soil or substrate in that it cannot be stored in a closed, airtight container. This is because topsoil contains living organisms and organic matter that require air as well as moisture to thrive and support plants. With the right storage method, soil can be kept free from erosion and safe from any damage that may occur naturally.
Other Tips to Protect a Garden’s Topsoil
- Adjust irrigation systems. Consider a switch to drip irrigation, which can be more gentle on soil versus other watering methods. Also, be more mindful of watering methods or use cover crops between growing seasons. Avoid over-watering or watering too quickly, so the soil has a chance to absorb all the moisture.
- Use erosion prevention practices. Things such as adjusting watering methods and placing burlap material or netting over any soil on an incline can help.
- Use compost. Compost is full of many beneficial microorganisms and other organic matter that can help build up additional topsoil. Organic compost can be purchased from a local gardening center, but it is also possible to make a compost pile at home, which is highly recommended.
Bonus Tip: Storing Other Organic Materials Long-Term
Throughout this article, we have discussed the importance of storing topsoil. However, topsoil is not the only organic matter that should be preserved between growing seasons! For a thriving, healthy garden, gardeners should also consider storing and preserving their mulch and compost as well.
The following are a few extra tips for storing mulch and compost:
Leftover mulch can be stored on top of a large tarp. Make sure that the mulch is spread out to allow proper airflow. To prevent mildew and mold or excessive moisture from heavy rainfall, cover the top of the pile with a light breathable fabric such as burlap. Turn the mulch frequently and allow some sun exposure during clear days.
If remaining mulch is still in its sealed bags, poke a couple of small holes in the bag to allow the mulch to breathe for short-term storage. For long-term storage, open and pour the entire bag of mulch onto a tarp and keep it maintained, as mentioned previously.
*Note: Mulch can quickly turn sour if it is not stored correctly. Avoid storing this material in air-tight places, and keep it in a relatively dry area. This is because mulch needs plenty of oxygen to avoid carbohydrates from breaking down and fermenting; the result would be highly acidic mulch that could cause harm to future plants.
Similarly to topsoil, compost needs protection from erosion above all else. Make sure to use a light tarp and stakes over a ground-based compost pile to prevent heavy rain and other natural agents from washing particles away.
If compost is currently held in a container, make sure the container has adequate air holes to allow the material to breathe. Ideally, plastic bins work best since they can expand with the compost and weather.
Topsoil is vital for gardens because it contains the appropriate levels of organic matter and nutrients that allow plants to develop fruitfully. However, because topsoil is easily erodible and takes years to develop in the first place, it is crucial to store and preserve the topsoil available to ensure the continued growth of healthy plants over time.
Several methods are out there to preserve topsoil over the long-term, including using cover crops, avoiding the use of pesticides and more. By following the above tips for storing and maintaining topsoil, it will be available to continue using to help the garden thrive for many seasons to come.
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