Greenspace Soil Assessment

Findings and Recommendations from Steve Blandford, NRCS, Soil Scientist (Pedologist) 9/24/26 Site Visit to Bob O Link Greenspace

Summary of findings

The greenspace soils are heavily disturbed and do not reflect the natural soil profile that would have formed on this site. When the surrounding houses and sewer lines were built, the original landscape, which was likely a 10–12% slope, was cut, filled, and graded flat. Sewer trenches were dug out, backfilled with gravel, and covered over. The creek that once ran through part of the area was channelized or removed, and the ground was reshaped as cut-and-fill. As a result, the natural sequence of topsoil, subsoil, and parent material has been scrambled or buried, and very little of the original soil remains in place.

Two soil types were compared on site.

The first is a residual soil formed from the underlying limestone bedrock. It has a reddish tint, is silty, and has relatively high natural fertility because the phosphatic limestone weathers phosphorus into the soil. That same fertility is one of the reasons the horse industry settled in central Kentucky. The top portion is silty and easily breaks apart (see photo); the bottom portion is limestone bedrock and is hard. 

The second is an alluvial soil (below), deposited by water rather than formed from the bedrock beneath it. It is extremely silty, with the feel of cooking flour, and shows gray coloring and iron and manganese staining. The gray is not clay. It indicates a lack of oxygen from a water table that sits in that layer for much of the year. The stains mark where water slows down and iron and manganese precipitate out. This soil is a wet, poorly aerated soil, and its fertility comes largely from nutrients washing in from surrounding slopes. In an urban setting, those inputs often include runoff from over-fertilized and chemically treated lawns.

The most significant finding was severe compaction. A penetrometer reading exceeded 300 PSI, high enough that the probe could not be pushed into the ground.

Roots are generally restricted well below that level. The soil particles have become cemented together, which gives the ground a very high bulk density (weight per unit of volume). Compaction at this level limits air and water movement, root growth, and the microbial life that builds healthy soil. The existing turf and the organic material on site are also poor food sources for soil microorganisms. They are high in lignin, break down slowly, and contribute little stable organic matter.

Recommendations for regenerating the soil

Background on how healthy soil works

A healthy soil is roughly 45% mineral matter, 25% air, 25% water, and 5% organic matter. The mineral portion comes from the parent material and can't be changed. The other 55% is shaped by land management, and that is what has been degraded here. The 5% organic matter drives the whole system: it holds water and nutrients and feeds the soil microorganisms, which can number in the billions in a single tablespoon of healthy soil. Those organisms need a steady supply of organic material, such as roots and plant residue, to convert into stable organic matter. More organic matter comes from roots below ground than from plant material on the surface.

Steve Blandford recommended first, relieve compaction, then build organic matter with high-biomass plants.

1. Mechanically break up compaction with a soil ripper. A ripper (also called a subsoiler) pulls shanks through the ground to fracture the cemented layers, reopening pore space for air, water, and roots. Plant roots and soil biology alone can't penetrate soil at 300+ PSI, so this step is what makes everything possible after it.

2. Immediately follow with a cover crop of cereal rye, rapeseed, and clover. Planting right after ripping keeps the loosened soil from settling and re-cementing. Each species plays a different role. Cereal rye produces heavy top growth and a dense, fibrous root system, which adds a large volume of organic material, holds the soil together, and suppresses weeds. Rapeseed, a brassica, has a strong taproot that drives deeper into the soil and keeps channels open after ripping; when it dies back, those root channels remain as pathways for water, air, and future roots. Clover, a legume, fixes nitrogen from the air, feeding the soil and the following plantings while adding more biomass.

3. Keep the soil covered and growing. The goal is continuous living roots and a steady supply of high-residue organic material for soil microorganisms. Over time, this raises organic matter, improves structure, and keeps particles from re-cementing.

4. Reduce chemical and fertilizer inputs. The site already receives nutrients from surrounding runoff, and over-fertilization and over-application of chemicals are common problems in urban settings.

Practical considerations for our project

Several site details affect how these recommendations are carried out:

1. Mowed vs. naturalized areas. Determine what ground stays mowed for walking and activities, and which gets converted to deep-rooted plantings. 🎬Jennifer will identify on greenspace map.

• Buried utilities: The sewer lines run through the site, so utility locates should be completed before any ripping. We must coordinate with “before you dig” to mark utilities and LFUCG on the sanitary sewer easement, since ripping over or next to those lines may need their sign-off.

• Existing trees: Ripping should stay outside the root zones of the large existing trees. They are already declining and severing roots could speed that decline.
• Soil moisture: Ripping works best when the soil is fairly dry. Ripping wet ground smears and compacts it instead of fracturing it. The gray, poorly drained alluvial areas may only be dry enough during late summer or fall.
• Seeding timing: Late September into October is a good window for cereal rye in Kentucky, and it will overwinter reliably. Rapeseed and clover establish best when seeded somewhat earlier in fall, so a planting this fall should happen soon.
• Phased planting: Because the addition of trees, pollinators and meadow conversion are going in over 3-5 years, the ripping and cover crop sequence can be done ahead of each phase. Areas scheduled for later years would build soil under cover crops until they are planted.

A follow-up penetrometer reading after the first cover crop season would show how much the compaction has improved, and a basic soil test (pH, phosphorus, potassium, organic matter) would give a baseline for tracking progress.

🎬NRCS Conservation Plan update. Kathryn will revise our existing conservation plan to add today’s findings (compaction, the two soil types, the ripping and cover crop sequence) into it. We will review these findings at a scheduled meeting on October 12.

Develop partners

Steve recommended we establish partners who can help achieve our goals. We discussed several key experts in Lexington and the team is working on reaching out. 

We are very thankful to Steve for teaching us about good soil and bad soil, explaining the history of our greenspace soil disturbances and what we can do to restore healthy soil.  👏👏👏