Term
| What are the 5 ideal natural soil horizons? |
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Definition
O Horizon: organic
A horizon: topsoil
B horizon: subsoil
C horizon: substratum or parent material
R horizon: bedrock |
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Term
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Definition
| (organic) a mulch layer that reduces evaporative water losses, maintains surface temps, contributes organic matter. |
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Term
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Definition
| Topsoil: incorporated organic matter, organism population, rooting medium for most plants |
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Term
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Definition
| Subsoil: added rooting volume for stability, nutrients and water storage. |
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Term
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Definition
| substratum: deep rooting and drainage volume. More important to good plant growth in shallow soils. |
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Term
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Definition
| Bedrock. consolidated soil material from which the soil profile may have been derived. |
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Term
| What have insurers listed as the major cause for liability claims against landscape architects? |
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Definition
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Term
| What is the ideal depth to bedrock, or the impervious horizon? |
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Definition
| At least 24-30 inches for most planting designs, 36" ideal for most situations. |
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Term
| What are the guidelines for coarse fragments in topsoil? |
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Definition
| stones and or building rubble should be less than 2" in diameter and less than 25% by volume within 24" of soil surface. |
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Term
| What are effective amendments for heavy texture soils? |
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Definition
| organic matter, expanded shale, calcined clay or other similar materials in appropriate proportions. contact soil scientist for best specs |
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Term
| What is the most influential soil physical property? |
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Definition
| Soil texture or particle size distribution |
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Term
| List several designed soil properties. |
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Definition
soil texture
density
susceptibility to compaction
structure formation,
drainage and aeration
relative fertility |
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Term
| How is soil texture defined (ratio) |
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Definition
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Term
| What are the particle size ranges for sand, silt and clay? |
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Definition
Coarse Fragments: >2mm
Sand: 2-0.05mm
Silt: 0.05-0.002mm
Clay: <0.002 |
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Term
| What are typical organic matter dry weight specifications for topsoil/subsoil? |
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Definition
5-10% dry weight for topsoil
1-3% for subsoil
*Calculate volume values by multiplying dry weight by 2.2 (this is for landscape soils NOT potting soils which have more organic matter). |
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Term
| What is the best ASTM soil test for general soil info? |
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Definition
| *(best all around) Std. Mthd. for Saturated Hydraulic conductivity, Water Retention, Porosity, Particle Density and Bulk Density |
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Term
| What is one method to lower soil pH in an appropriate manner? |
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Definition
| application of elemental sulfur (NOT over-adding organic matter) |
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Term
| What are the guidelines for placing soil on flat terrain? |
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Definition
| Place in lifts no greater than 6", compacting each level to ensure elimination of air pockets and soft spots. |
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Term
| What are the guidelines for placing soil on slopes? |
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Definition
| The surface should be deeply scarified (6" or more using using a chisel plow), with removal of some of the the stone in the case of the stoney surface. On steeper slopes the existing sub grade should be stepped or terraced. |
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Term
| What are the 3 layers of design soil profiles? |
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Definition
S-1: topsoil
S-2: subsoil
S-3: drainage layer |
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Term
| Describe the garden profile for general purpose garden soil. |
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Definition
S1: 0-6" Loam to silt loam with 20% volume basis organic matter
S2: 6-8" Loam with 5% vol. organic matter
S3: 4"+depth of sandy loam |
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Term
| What are the basic guidelines for tree planting without understory? |
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Definition
| Excavate pit to depth slightly less than depth of rootball; flare out walls of pit; infill with UNAMENDED soil, loosening of soil is adequate; mulch layer 4" or less, extends from near root collar, which is NOT covered, out to beyond the disturbed soil. |
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Term
| What is the max recommended slope acceptable for tree planting? |
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Definition
| 2:1, unless special geotechnical engineering subsurface provisions are made to stabilize the slope. |
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Term
| What are some general guidelines for designing planting berms? |
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Definition
1. provide deliberate drainage
2. existing soil to be covered by the berm should be shaped with a slight mound longitudinal to the berm.
3. Only use geotextile if the berm is being built on poorly drained soil.
4. Keep slopes shallow (2:1 or 3:1) so they are accessible for maintenance. |
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