Restoring soil health in established landscapes

This new (October 2026) content is under construction. 

Introduction

Restoring soil health in residential, urban, parkland, roadside and other established landscapes can substantially decrease runoff from or directed to these areas, reducing and improving stormwater quality. These landscapes are typically managed by landowners, organizations, and municipalities that have long-term interests that facilitate multi-year, iterative improvements one step at a time to minimize costs. Therefore, soil health restoration projects on existing landscapes are well suited to adaptive management, which can also optimize results compared to short-term projects. 

For construction and development projects with an end date and handoff to the landowner, the more linear approach described in Preserving and Restoring Soil Health in Construction will likely be more practical. For background information and a review of the literature supporting these approaches, see Soil Health in Stormwater - Intro and Research Summary.

An adaptive management approach to achieve soil health in existing landscapes facilitates the selection of soil health practices and a framework to assess and adapt as needed to meet strategic goals. Adaptive management also aims to maximize outcomes for the minimum effort and cost.  How and if each of the soil health restoration principles are applied will vary based on the land use history, future, and soil conditions. The soil health principles are: 

1. Decompact or aerate to reset unhealthy soil, if necessary
2. Increase soil organic matter
3. Establish diverse, dense, and deep-rooted vegetation
4. Minimize physical and chemical disturbance to maintain healthy soil

This guide provides a practical restoration framework for existing developed landscapes that blends an adaptive management framework with a simple set of soil health measures for straightforward management decisions based on results.

Soil Restoration Framework 

An adaptive management framework iterates between three phases: 1) Assess - rapidly measure key metrics to guide restoration, 2) Plan - evaluate assessment; decide priority practices, and 3) Implement - put plan to practice. The key to success is that each of these phases can be easy to complete, so that the full cycle can be done annually for the 3-5 years it takes to restore soil health. The effort should also decrease substantially after outcomes (i.e. infiltration rates) meet goals, and iterative cycles can be extended to every 3-5 years.

1. Assess: Rapidly measure key metrics to guide restoration

Assessing soil health at a restoration can typically be done by two people with modest training and inexpensive equipment in a half a day in the field. To make this possible, each measurement needs to focus on key metrics of soil structure that are expected to change during restoration and that will be used for developing and adapting a restoration plan. This primary soil health assessment should be done before developing a soil restoration plan, and then annually for 3-5 years or until desired outcomes are achieved. 

Refer to Soil Health Assessment Guide for details on the recommended methods to assess key soil health metrics. In summary, these methods are: 

• Compaction by penetrometer: This rapid and informative measurement initiates every survey. Equipment: static cone penetrometer with a pressure dial ($200-$800) for quantitative measurements, or tile probe or driveway marker rod ($5-$50) for qualitative assessment. 1-2 minutes per location, with 10 per site.
• Infiltration by ring falling head: This inexpensive but effective measurement of time to infiltrate 2 inches of water provides sufficient information to soil health status and progress toward restoration goals. Simply measure the time to infiltrate the 1st inch and then the 2nd inch of water, or the approximate depth of water infiltrated in 30 minutes, whichever comes first. Use a small double infiltration ring (6”&12” x 4”, $200-$500) or a homemade single ring. 35 minutes per location, with 3 per site. Tests listed below can be done while waiting.
• Topsoil depth and sample collection: Topsoil is the uppermost layer of soil that is darker in color and looser in structure than the soil layers below. The depth of topsoil varies depending on position (convexity) in the landscape. Determining the topsoil can be done using a shovel and must be assessed at several places in the landscape, being certain to measure where the soil is convex, concave, and planar. 
• Soil texture by feel: Soil texture is the proportion of sand, silt, and clay in soil. Using bare hands with appropriately moistened soil, a person can roughly determine soil texture using a flowchart. Texture will often vary with soil depth and is an important measurement to determine a soil’s baseline hydraulic properties. 
• Soil structure and color by visual assessment: A simple scoring system based on the shape of soil aggregates provides information on structural porosity and macropore connectivity that indicate healthy soils with high infiltration and water holding capacity. Color provides a measure of organic matter content. Combine with soil texture by ribbon test for the first visit at each site. Equipment: shape and color charts, or mobile phone color app (optional). 2-5 minutes per location.
• Aggregate stability in water by bottle cap test: A simple scoring system based on how long soil aggregates can retain their shape when submerged in water. Equipment: water bottle and cap or shallow cup. 2-5 minutes per location (plus lab time to dry aggregates if soil is moist or if you are doing the Slakes app method).
• Plant biodiversity and density by visual assessment. A qualitative assessment that takes less than 15 minutes. The existing plants at a site indicate the health of the soil and can be used to decide if overseeding or planting larger woody plants would help.

A secondary soil health assessment is optional but can provide additional information to guide large or high-profile soil health restoration projects. These measurements include collecting samples in the field for laboratory analysis:

• Soil organic matter: to guide how much compost to add, when it is cheaper to measure it than to add extra.
• Basic soil chemistry: such as nutrients and pH, to determine quantities of soil amendments such as lime or fertilizer to optimize vegetation establishment and growth when it is cheaper to measure it than to add extra.
• Bulk Density: profiles are a more precise measurement of soil compaction, root penetration, and porosity (i.e. saturated water holding), if collected with the right kind of soil recovery probe with plastic liner ($100-$300), for the purpose of documenting improvements to soil health. 
• Soil Texture: estimate the texture of the topsoil. This will be needed for fertilizer recommendations and is good to know when considering other organic soil amendments and the influence soil health practices would have on infiltration rates. (While we are usually talking about practices to decrease compaction and increase infiltration, sometimes the desired outcome is to slow down infiltration and hold water in the root zone better by amending coarse soils with compost.) 

2. Plan: Consider the assessment results and select practices

Based on findings from the soil health assessment, a soil restoration plan should include which soil health principles, and which specific practices and implementation details could be most beneficial. Considering context (and issues of any given soil helps determine which combination of soil health principles are needed for soil restoration. The plan should focus on practical steps toward a longer-term goal; people tend to overestimate what can be done in a single year, but underestimate what is achievable over three years.

Generally, soil health can be restored by applying two or more of the four principles. No single restoration practice will restore soil health in the long term. For instance, adding compost without plants might briefly increase soil organic matter, but without roots to continue cycling and recycling the organic matter, soil aggregates will not develop. Another example, if the soil is compacted, adding compost and plants may not succeed if the compaction is too great for plants to establish. 

In summary, the soil health restoration plan should:

• Consider the context and issues 
• Consider soil health assessment results;
• Include two or more soil health principles;
• Consider the practicality of implementation before next growing season; and
• Take an achievable step toward a multi-year restoration vision. 

Below are considerations and various practices associated with each of the four soil health principles.

Considerations for Principle 1: Decompact or aerate to reset soil

Soils compacted by machinery, frequent foot-traffic, or in other ways can severely restrict plant growth, water infiltration, and aeration of plant roots. In severe cases, decompaction is a required step to reset soil to begin soil health restoration. Even in milder cases, decompaction can accelerate soil restoration outcomes. Establishing dense, diverse and deep-rooted vegetation is required to maintain and expand the benefits of decompaction, as bare soils will largely recompact within a year.

Decompaction should be considered a resetting event applied once or twice to a compacted soil. Decompaction is not intended for ongoing maintenance because it will break soil aggregation. In addition, decompaction methods that aggressively mix or turn over the soil should be avoided, and instead, methods that lift the soil are preferred. 

Assessment results to consider

Penetrometry is a rapid and effective field screening tool for identifying the depths of compacted layers down to 24”. Penetration resistance as low as 150 psi can affect root growth (1 MPa) and values of about 300 psi or greater (2 MPa) restrict root growth. Soil compacted by machinery can have penetration resistance as high as 1,500 psi (10 MPa). MnDOT has been using 200 psi as an action threshold for decompaction, and some cities and watershed districts are specifying <200 psi in ordinances (Warren Tuel, personal communication). 

Penetrometry results can vary substantially with differences in soil texture and moisture (drier soils have higher resistance). Ideally, measurements should be made when soil moisture is near field capacity, roughly 1-3 days after a rain event. If soil is too dry, penetrometry results will be misleadingly high and should not be used in decision-making. For this reason, penetrometry is potentially less quantitative than bulk density for comparing sites or tracking changes over time. 

Bulk density measured at multiple depths is the gold standard for assessing soil compaction, as it is a direct measurement of the soil and not a function of soil moisture (in contrast to penetrometry). New methods that use small diameter, vertical coring (e.g. soil recovery probe with plastic liner) can rapidly collect 12” to 24” of soil profile into a plastic sleeve for subsetting and analysis in the office or lab. 

Bulk density values as low as 1.1 to 1.4 g/cm³ can impact plant growth depending on soil texture, and values >1.6 g/cm³ restrict root growth. The below table identified root limiting and restricting bulk densities. Mechanical decompaction is required to facilitate vegetation to grow in such soils if bulk density is not under the ideal limit. 

For soils with penetration resistance >200 psi or bulk density >1.4 g/cm³ in the upper 24 inches of soil, decompaction is necessary to start a soil health restoration project, as plant roots cannot grow into such soils. Subsoil or deep rip to depths below the hardpan (i.e. interval of highest penetration resistance, commonly between 8-12 inches deep) for best results. Based on practical limits to equipment selection and sizing for a site, it may be more practical to decompact to shallower depths (5”-8”) in the first year, enabling plant roots to further decompact the upper layers before subsoiling to below the hardpan (14”-18”) in the second year. 

For soils with penetration resistance 150-300 psi or bulk density 1.1-1.6 g/cm³ in the upper 12 inches of soil, decompaction can accelerate soil health restoration by expanding water storage capacity and the volume of soil that plant roots can easily access for nutrients and moisture.

For soils capping a contaminated site, shallow groundwater, or karst geology, do not decompact. Survey every urban and suburban environment for a history of contamination and high groundwater table. For example, in exceedingly permeable soils such as karsts and sands, infiltrating to groundwater too fast can be a problem with insufficient contact time for soils to filter chemicals (Tirpak et al. 2021). 

Practices to consider

Plug Core Aeration with hollow core tines pulls ½”- to ¾”-diameter plugs out and onto the soil surface to open holes 3-6 inches deep for compost and expanded root growth. Deep plug aeration is most often applied over existing turf grass. 

“Spike aeration” and “Tine aeration” are not effective at decompacting soils or increasing macropores, as it locally compresses soil structures.

Examples of plug core aeration equipment include: AE30S Stand-On Aerator (Specs, Pricing & More) - Bobcat Company and 64" ProCore® 864 Turf Aerator | Toro. Refer to Core Aeration of Lawns | Yard and Garden | Iowa State University Extension for more information.

Tillage refers to a wide range of methods that mix and turn over the upper 4-8 inches of soil. In the context of soil health, tillage is primarily useful to mix compost into low organic matter soils after construction and before seeding. A spading machine or power spader is the preferred method, as it lifts the soil without creating a hardpan, inverting the profile, or destroying beneficial soil structure. High-speed rototilling should be avoided on soils with granular or blocky structures, as it destroys soil aggregates and can create a hardpan. The use of roto-tillers should be limited to structureless soils often found post-construction.

[IMAGE COMING - Power spading machine]

Subsoiling pulls a steel shank through the soil 14 to 26 inches deep on bare or vegetated soil, cutting a narrow channel, lifting the soil slightly with a wedged point that ideally has wings. Subsoiling cracks compacted hardpans without inverting or mixing the topsoil. Deep ripping is a related practice that should be avoided because it is much more aggressive and can mix the subsoil to the surface.

A guide to successful subsoiling | CETAB+ (Weill, 2015) provides equipment and method information for subsoiling and is a recommended resource if subsoiling will be done. Highlights from this document include: When subsoiling over existing vegetation, lead each shank with a straight-cutting disks to slice through thatch and roots and avoid damaging the vegetation (Figure 2) The depth of subsoiling may need to be adjusted to accommodate the power of the selected equipment. In very compacted soils, it may be necessary to first subsoil to an intermediate depth, then do a second pass 2” to 6” deeper, possibly waiting a year or two for plant roots to assist with decompacting the shallower soils. When a second subsoiling pass is done, even years later, there are benefits to changing the direction of the pass, so that the channels cross and inter-connect. Subsoiling generally requires machinery that can pull 35-75 HP per subsoiler shank, depending on the operating depth, soil compaction, and soil moisture content.

Refer to the Restoring and Protecting Soil in Construction - Decompact subsoils after construction for more information on subsoiling.

Considerations for Principle 2: Increase soil organic matter

Most soils benefit from adding compost. Fresh organic matter boosts microbial activity and plant growth that create and maintain stable soil aggregates, granular structure, and macropores. The goal is for organic matter content to be between 5-15% over a full 6-8 inches of topsoil depth. Benefits increase with increasing organic matter over this entire range, so adding too much compost will not negatively impact soil health (ISWMM Chapter 5 Section 6). Note that soil organic matter is 40-60% organic carbon, so if your soil test reports organic carbon, convert this value to organic matter (SOC = SOM ÷ 1.72) for decision-making. 

Note on exceptions to increasing organic matter and nutrients: There are some sites where lower soil organic matter and nutrients are necessary for restoration. In particular, sites where competition from invasive species such as reed canary grass, brome, Canada thistle, etc. are an established concern. Additionally, some types of plants, such as dry prairie species, will have a better chance of success with lower soil organic matter and nutrients. Solar panel sites are another example where limiting vegetation height may mean limiting soil amendments.

Assessment results to consider

Applying compost is not needed if the soil is determined healthy by all of the following criteria:

• Penetrometry readings are below 150 psi at all depths down to 16 inches deep.
• Soil structure is granular, crumbly, and full of roots down to at least 6 inches deep.
• Soil aggregates are stable in water for 30 seconds of swirling.
• Soil color is dark brown or black down to at least 6 inches deep.
• Infiltration of 2 inches of water takes less than 15 minutes.

Practices to consider

For existing herbaceous vegetation cover – such as lawn turf, meadow, or prairie – apply a ½” to ¾” compost layer after mowing and ideally coinciding with plug aeration to 4-5” deep. This allows the vegetation to grow through the compost. The compost is too deep if the leaves do not emerge, but can be fixed by raking the compost down into the plants. Soils with low organic content may require several years of repeated practice to achieve the target of >5% organic matter in the top 6 inches of soil. This practice is equivalent to Iowa’s Soil Quality Restoration (SQR) Method 8. This is often combined with overseeding (see Establish diverse, dense, and deep-rooted vegetation below). If no rain is in the forecast, irrigating to accelerate compost incorporation into the soil and reduce smothering or “burning” underlying vegetation.

For lawn maintenance, organic matter can be continuously added by using a mulching lawnmower and mowing fall leaves into the lawn rather than raking and removing leaves. In lawns that receive heavy loads of leaves, it may be necessary to spread leaves to a 2 inch blanket before mowing them down, repeating 2-3 times per fall. Leaving thick piles of leaves will kill the underlying vegetation, whereas mowing leaves into a ½”-¾“ blanket of mulch is similar to a thin compost application.

For landscaping with mixed herbaceous and woody vegetation that includes shrubs and trees, a 1” to 3” compost blanket can be applied as a mulch as long as it doesn’t smother desired herbaceous vegetation. Ideally perform plug aeration to 4-5” deep before applying compost to help incorporation into topsoil and for decompaction. Fall leaves should be left in place to develop a litter layer that serves as mulch for vegetation and is critical for overwintering of beneficial insects. (Note that some tree species may be sensitive to plug aeration within the drip line perimeter.) 

For bare soils with no vegetation, apply 2” to 4” of compost then till into the top 6 to 9 inches of existing soil using a spading machine or power spader, which is the preferred method as it lifts the soil without creating a hardpan, inverting the profile, or destroying beneficial soil structure. Aggressive, high-speed rototilling can destroy existing soil aggregates (see Decompact guidance below). Select the amount of compost with the target of >5% organic matter in the top 6” of soil, based on the soil organic matter content in the existing soil. A ½” compost blanket mixed into 6 inches of topsoil will increase organic matter content by about 1%. Note that even for bare soils that contain >5% organic matter, a minimum application of 1” of compost is recommended to kickstart the microbial community with an inoculum and fresh “food”, especially after the topsoil has been stored for construction or otherwise degraded.

Considerations for Principle 3: Establish diverse, dense, and deep-rooted vegetation

A diversity of vegetation species and functional groups that continuously covers the soil is required to develop and maintain healthy soils with a granular structure and macropores to infiltrate and store stormwater. Continuous cover protects soil from sun and raindrops that inhibit soil life and destroy soil aggregates. Actively growing roots, especially deep tap roots, open and maintain macropores and feed beneficial soil life (i.e. bacteria, fungi, worms, insects) that create stable soil aggregates. Be sure to check local ordinances regarding site-specific setbacks, right-of-way, plant height, and species limitations. 

Assessment results to consider

Consider results from the vegetation biodiversity and density by visual assessment. Sites that lack diversity, dense cover, and deep-rooted vegetation are good candidates for soil health restoration. Basic Soil Chemistry (Nutrients and pH) test results can provide guidance on how nutrient addition or supplementation may be necessary to support plant growth. 

Practices to consider

Nutrient additions using compost and fertilizer and lime or other soil amendments may support plant establishment and accelerate soil health restoration. This is especially true when starting with a depleted soil. MNDOT recommends using a Type 3 Slow-Release Fertilizer or a Type 4 Natural-Based Fertilizer for the best results. Agricultural lime (i.e. pulverized limestone) not only buffers pH to facilitate the availability of soil nutrients, it also helps with the formation of stable soil aggregates due to its calcium and magnesium ions that act as flocculants for fine minerals.

For soils with bare spots or low plant diversity, overseed with a diverse seed mix selected for the soil type and desired land use context. Overseeding is most successful when done in combination with a ½” to ¾” compost blanket and aeration, and when applied in the spring or fall, depending on seed species. See “Recommended seed mixes and planting guides” below for details.

Existing landscaping is often maintained in what has been referred to as a “sea of mulch”, which is large spaces of mulch between dotted plants. A better method for soil health is to use living mulches or increase the plant density. In a well-established planting bed, ideally no mulch is necessary because plants to the job of much – covering the ground, retaining moisture, and preventing weed growth. If mulch is deemed necessary, an organic mulch like woodchips is preferred to the common landscape fabric and rock. Organic mulch provides organic matter and better soil conditions, whereas rock heats the soil, limits soil function, and reduces soil biologic diversity. In addition to dense plantings, native plants and diverse plants also provide better habitat for soil microbes.

Turf conversions may be considered for any existing turf that is not used. Native plants can provide improved resiliency and provide benefits to pollinators and wildlife. Mini forests are a newer practice gaining traction. The dense and quick-growing planting has the potential to offer many benefits, including those to soil health. 

For sites with invasive plants, treatment to remove invasive plant species is highly recommended, as invasive plants will outcompete other plants with the negative effect of decreasing overall plant diversity. Invasives are also known to alter soil chemistry and nutrient cycles. Such treatments are one case where herbicides may be necessary to reset a system at the start of a soil health restoration project. Treatments are often immediately followed by planting, to avoid bare soils and suppress the growth of additional invasives. 

Recommended seed mixes for cover crops, pollinator lawns, low-mow lawns, wildflower meadows, and prairie typically contain 7 to 30+ species of grasses, sedges, legumes, and other forbs (broadleafs & wildflowers) that include several nitrogen-fixers and deep rooting plants. Native plant species provide many long-term benefits (i.e. drought and cold resiliency) but are often slower to establish. In some cases, a seed mix may include “nurse” crops that only live for a couple of seasons to help establish dense vegetation more quickly, build soil structure, and contribute organic matter as they senesce, but these must be used with caution, especially with native species, because they can be overly competitive. Seed mixes should have a blend of cool and warm season grasses for a greater duration of green grass during the growing season.

Higher plant density is a better option to reduce weeds than landscaping cloth, natural and rubber mulches, or landscaping rock. A living mulch that is comprised of use overlapping layers (sometimes called a “matrix”) of native grasses, sedges, and flowering perennials are an effective weed-suppressant that grow into a self-sustaining ecosystem, eliminating the need for annual re-mulching. 

Many excellent planting guides exist for selecting seed mixes and establishing diverse, dense, and deep-rooted vegetation for any soil type and sun exposure. A few resources include:

• Lawns to Legumes: Your Yard Can BEE the Change | MN Board of Water, Soil Resources
• A Pollinator Paradise in Your Own Backyard | Minnesota Land Trust
• Guide to the New 2024 MnDOT Seed Mixes and MnDOT Seeding Manual 2024
• BWSR Seed Mixes

Considerations for Principle 4: Minimize disturbance to maintain healthy soil

Protect areas with healthy soils or soils undergoing restoration. Physical disturbance can destroy stable aggregates, collapse macropores, compact soils, and disrupt plant growth. Chemical disturbance with herbicides and pesticides reduces the vitality and diversity of vegetation, soil microbes, and soil fauna, which eventually leads to a reduction in stable aggregates and structural porosity. Minimizing disturbances is important to maintaining a healthy soil’s ability to infiltrate and store stormwater.

Assessment results to consider

Understanding the context and use of the land will help you understand if there are opportunities to minimize disturbance. Details such as how the space is used, the frequency and type of mowing, any chemical use, and areas of high foot or vehicular traffic should be considered.

Practices to consider

Alternate mowing practices like avoiding mowing when the soil is wet and decreased mowing frequency can help protect soils from compaction. Similarly, switching to a compost or organic nutrient source can help protect soil biology and health. In some cases, switching the land cover may be appropriate. For instance, if a lawn or a portion of the lawn is not used, consider converting the lawn to a native, perennial vegetative cover. Creating dedicated walkways can help minimize compaction. Use landscaping to direct traffic, for instance, by planting shrubs to limit foot traffic. 

3. Implement: Put plan into practice

Once the plan is complete, implementing the plan is the final step in the iteration of the adaptive management framework. Adaptive management also means that conditions should be monitored and adjustments made accordingly. For instance, watch over the growing season to assess if irrigation plans should be altered, unanticipated erosion needs to be addressed, or other unplanned conditions emerge.

After the first year, re-assess conditions and the original plan and adjust as necessary. Soil health field assessment results, stories from operations and management staff, and a visual assessment and comparison of the plan to what happened, succeeded, or failed are all valuable to adjusting the plan.

Example Applications of Adaptive Management Framework for Soil Restoration 

Below are hypothetical scenarios provided as examples of how to apply the adaptive management framework for soil restoration.

Turf improvement scenario

Context and issues: A park manager wants to improve portions of turf in one of her parks. The targeted area is a relatively flat, multi-use lawn adjacent to a picnic area, which has bare spots that erode onto sidewalks after heavy rain. Previous maintenance records show regular applications of fertilizers, lime, and broad-leaf herbicides to prevent dandelions.

The soil is assessed with the following results:

• Compaction: penetrometry 170 to 280 psi, with no clear depth trends or hardpan
• Topsoil: 6-8 inches of dark brown topsoil that ribbons 1-2” (clay loam). Platy structure. Aggregates disintegrate when swirled (submerged in water). 
• Subsoil: Gradual transitions to tan subsoil of similar texture.
• Infiltration: 0.8 to 1.2 inches before 30 min limit.
• Vegetation: 20% to 50% bare soils, with more bare patches under shade trees or in paths. 3-4 different kinds of grasses, no other herbaceous plants. 4 tree species around the perimeter. No invasives.

Evaluation of assessment results suggests strong potential for soil health improvement. Based on this information, the plan is to incorporate all four soil restoration principles: 1) aeration, 2) increase organic matter, 3) increase vegetation density and diversity, and 4) minimize physical disturbance. The specific practices that will be used are:

Aerating five inches deep with a plug core aerator

• Spreading ¾” of compost
• Overseeding with a shade-tolerant, pollinator-friendly lawn mix. The selected seed mix includes fine fescues (grasses), white clover (legume), creeping thyme, yaak yarrow and self-heal (other forbs).
• Irrigating during early seed establishment.
• Eliminating general application of broad-leaf herbicides, unless spot spraying for invasives. The park manager will work to educate her staff that dandelions are allowed as they are effective at decompacting soils. 

Implementation is planned for late August. The following spring and summer, progress is monitored and interventions are made, as necessary. The soil health assessment is planned to be done again roughly one year after the plants are established to help plan for the next round of the adaptive management cycle.

Infiltration basin improvement scenario 

Context and issues: An older infiltration basin with frequently-mowed turf has consistently pooled water for many days after large rainstorms, killing the grasses in some portions. Neighborhood meetings have raised interest in converting it to a wildflower meadow, which the MPCA Stormwater Manual suggests might also improve infiltration. Construction plans show that 6 inches of topsoil were imported to cover the subsoil after grading.

The soil is assessed with the following results:

• Compaction: penetrometry is 80-130 psi in top 4 inches, exceeds 300 psi near 5 inches, reads 400-600 psi until it returns to <300 psi around 9-11 inches, then remains 200-250 psi down to 20 inches. These results show a highly compacted layer that limits infiltration and plant growth
• Topsoil: 4-5 inches of light brown soil that barely forms a ribbon <1” and feels gritty (sandy loam) with subangular blocky structure. Aggregates disintegrate in water. Soil color suggests organic matter content is likely <3%.
• Subsoil: There is an abrupt transition around 5-6 inches to a soil with orange and light grey blotches, that feels gritty but forms a 1-2” ribbon (sandy clay loam) that has platy structure.
• Infiltration with double ring: First inch in 15-25 minutes. Second inch infiltrates less than ¼” before 30 minute time limit
• Vegetation: 10-20% bare in most locations. 100% bare for about 300 square feet that has a silty crust. Full sun everywhere. 2-3 different kinds of grasses, one legume, 2-4 other flowering plants. No shrubs or trees. Quack grass is extensive.

Based on this information, the plan is to incorporate all four soil restoration principles: 1) aeration, 2) increase organic matter, 3) increase vegetation density and diversity, and 3) minimize physical disturbance. The specific practices that will be used are:

• Eliminate quack grass with herbicide (to support other vegetation establishments).
• Decompact to 18” with a tractor-pulled wing-tipped shank subsoiler to break through the hardpan, expand the volume of soil available to plant roots, and improve infiltration. 
• Add two to three inches of compost and till into six inches of topsoil to increase organic matter to 5-8% and help new plants establish without need for irrigation. Rototilling is OK given that the existing soil does not have the beneficial granular aggregate structures.
• Seed with a cover crop and terminate the cover crop (including any weed seeds or quack grass that germinates) in early fall.
• Plant with a diverse native seed mix in the later fall. A full-sun, storm basin seed mix is selected that contains 6-9 grass species, 5-8 sedges, and 20-30 forbs.
• The planting will need to be managed for the first few years. Intermittent mowing (before weed plants set seed) is likely necessary for the first 1-3 years. Mowing will be planned for when the soils are drier to avoid recompacting the soil.
• Reseeding may be needed if establishment is poor. Weed management could be necessary if problematic areas emerge. Fire may be considered as a management tool.

The plan is first implemented in early summer of the next growing season and throughout the year. That next year, soils can again be assessed. The soil assessment results are expected to improve through the following years as the native plant community reaches maturity.

Landscaping improvement scenario

Context and issues: A grounds manager has been asked to increase the greenery between buildings while minimizing long-term maintenance costs. The mixed border plantings along building foundations and between paths are sparsely planted with shrubs and heavily mulched with bark. Herbicide is used to control weeds that grow in the mulch. During large storms, runoff can erode and carry the mulch into paths.

The soil is assessed with the following results:

• Compaction: penetrometry 150 to 200 psi down to 20” deep.
• Topsoil: 5-8 inches of dark brown topsoil that barely forms a ribbon <1” and feels buttery (silt loam) with blocky structure.
• Aggregates disintegrate when swirled (submerged in water). 
• Subsoil: Gradual transitions to tan subsoil of similar texture.
• Infiltration: 0.4 to 0.9 inches before 30 min limit.
• Vegetation: 60% non-vegetated soils between shrubs and annuals, mostly mulched but with some bare channels eroded from previous storms. Three kinds of shrubs are present, with four species around the perimeter. No invasives. The site is contains partial shade to deep shade.

Evaluation of assessment results suggests strong potential for soil health improvement. Based on this information, the plan is to incorporate all four soil restoration principles: 1) aeration, 2) increase organic matter, 3) increase vegetation density and diversity, and 4) minimize chemical disturbance. The grounds manager proposes a small pilot plot of 1000 square feet that establishes a high density of perennial herbaceous plants between the shrubs that eliminates the need for annual applications of mulch and fertilizer and monthly herbicide treatments during the growing season. The specific practices that will be used are:

• Decompacting to 8” with a digging fork between shrubs
• Adding 3” of compost, gently mixing in compost into upper 6 inches of the soil.
• Several additional native species and some low growing and spreading ground cover species are selected to fill in the gaps between existing plants. Plugs and potted plants are purchased to accelerate vegetative growth.
• Plan to eliminate or substantially reduce the use of herbicides. 
• Plan to irrigate new plantings until established.

The plan is implemented in spring, with soil decompaction and plantings made before summer begins. The site is irrigated when needed through that first summer. The next spring, the soil health assessment is again completed and any changed to the plan developed.

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