Soil Flashcards
How is soil important for an arborist
relationship between tree root systems and the characteristics of soils in which they grow has a greater influence on the tree health than any other single factor. By knowing more about soil texture, structure, pH, and water holding capacity, the arborist will be better equipped to manage trees in an urban environment.
What is Soil
Soils are usually dominated by the geology of the soil parent material. By volume, ideal soils are composed of 45% mineral materials ( sand, silt, clay ), 50% open or pore space, and 5% organic matter and organisms. Over time soils develop layers due to rainfall, heating and cooling, chemical reactions and biological activities
What is the Soil profile
normally consists of five major horizons ( O, A, E, B, and C, ),
These layers can be distingui- shed by differences in color, texture, and smell, which can indicate varia- tions in drainage, organic and mineral content, and other characteristics changes.
What is the O layer
O horizon, is the organic layer of the top of the layer of soil profile that comprises of organic material in various stages of composition. It provides a source of nutrients for plants, and it buffers the soil from climatic extremes
What is A layer
is organic matter content is significantly less than that of the O horizon ( less than 20 percent organic matter). The A horizon contains most of the fine roots of trees and is typically biologically active. Although it is primarily composed of inorganic material ( sand, silt, and/ or clay), the A horizon is normally rich rich in organic matter, which gives this horizon its characteristic dark color
What is the E Horizon
when it exists, is found in these surface horizons and is lighter in color
What is the B Horizon
occurs below the A horizon ( and the E horizon, if present). It is a zone of accumulation where materials that have leached from the surface mix with soil particles from the lower parent materials.
What is the C layer
the deepest layer just above the bedrock and is composed of partially weathered parent material. Soil in this horizon is continually changing through the physical, chemical, and biological weathering of the parent material.
What area is the most favorable area for tree roots to grow
Most of the fine absorbing roots are most frequently found in the upper 6-10 inches of soil, and rarely are there any tree roots below than 3-4 ft.
What is Organic Matter
includes plants and animals that are alive, dead, or in some stage of decomposition. Organic matter improves soil structure, which results in increase water infiltration following rains and increase water- holding capacity of the soil; it also enhances root growth into more permeable soil (nitrates)
What is Pore Space
Refers to the amount of pores , or open space, between soil particles. Pore space may be formed due to the movement of roots, worms, and insects
Soil Texture affects this
What is Soil Texture
refers to relative fineness or coarseness of the soil particles, specifically the proportions of sand, silt, and clay
What is Loam Soil
a mixture of sand, silt and clay
very desirable medium that is used by farmers, gardeners, landscapers and property owners because of its very beneficial qualities.
What is Clay Soil
comprised of very fine mineral particles and not much organic materials. The resulting soil is quite sticky
What is Sandy Soil
generally coarse textured until 50 cm deep and consequently retain few nutrients and have a low water holding capacity. Q.palms
What is Silt Soil
Slippery when wet, not grainy or rocky. Soil itself can be called silt if its silt content is greater than 80%. When deposits of silt are compressed and the grains are pressed together, rocks such as siltstone form. Silt is created when rock is eroded, or worn away, by water and ice.
What is Soil Aggregates
Secondary groups or clumps that are chemical and physical changes and the activity of soil organisms cause soil particles ( sand, silt, and clay to be grouped together
What are Macropores
Large gaps between soil particles and aggregates are known as macropores. Macropores are normally filled with air.
What are micropores
Small gaps between soil particles and aggregates are called micropores. They tend to be filled with water.
What is gravitational water
Water that drains from the macropores under the force of gravity
What is Field Capacity
after gravitational water has drained away
What is capillary water
Water that remains is held in the micropores
What is Permanent wilting point
When water stress is prolonged and severe, plants may reach a point where they cannot recover
What is CEC
Soils Cation Exchange Capacity
Minerals required for tree growth ( essential elements ) dissolve in water, making them available for absorption by tree roots
*CEC can be used as a gauge of soil fertility.
What is Bulk Density
The amount of pore space is related to the bulk density of the soil. Bulk density is the mass ( weight ) of dried soil per unit of soil volume. Bulk density can be used to assess whether adequate pore space exists. It can also be used as a metric to determine the extent of compaction in the soil profile. Lower density is better for tree root growth and health.
What is Soil Compaction
increase in bulk density and a decreased in total pore space
soil aggregates, and accompanying pore space, are easily disrupted by soil compaction
soils with moderate moisture content are generally more easily compacted than dry soils or saturated soils.
MAJOR CAUSE TO TREE DIEBACK AND DECINE
What are anaroebic soils
occur when soils become saturated with water and oxygen is depleted
stop root development for most tree species and affect nutrient uptake. If soils has a gleyed (grayish) appearance, or a rotten egg odor, it is likely to have been saturated for an extended period
Problem with Drainage
urban soils have poor drainage
poor drainage is caused by soil compaction during construction
poor drainage is the result of surface and subsurface flow collecting at the base of slopes.
Solving poor drainage
improve drainage by breaking up the compacted layer or using other
compaction remediation techniques
installation of a french drain that intercepts flow and diverts it away from the area
drainage pipes can be installed under the poorly drained area
Antony and magnolia examples
why is mulching important
can reduce surface compaction and crusting, thereby improving water infiltration.
Soil erosion is reduced, weed competition is decreased, and temperature fluctuations are moderated
alter surface soil pH in some cases, least invasive method
they keep soil temperatures cool in the hot summer months, and they reduce evaporative water loss in hot, dry climates
Problems with Urban Soils
they lack organic material in the upper layer. Compaction in these soils along with asphalt, concrete make it difficult for water or gas to exchange underground. Drainage, pH, chemical contamination, nutrient deficiencies also can damage plants. Most trees in shopping centers, parkways along streets don’t often live long if they don’t have adequate room for roots to move through. Soils are completely different from before construction projects that make it hard for trees to survive very long. Compaction issues include, foot traffic, vehicle traffic, construction activities and even pigeons. Compaction damages soil aggregates, reduces macropore space ( air filled), increases bulk density, limits gas exchange, reduces water infiltration, and alters soil organism populations
What is Ph
potential hydrogen ions in the soil
affects the acid/alkaline balance of the soil
The range of pH is from 0-14 with the lower numbers indicating an acidic situation and the higher are alkaline levels.
*Plants can grow in the range of 5-8, but 6-6.5 is optimum
How do we adjust Ph in trees
the addition of lime will increase pH and sulfur will decrease it.
You can lower pH naturally by applying pine needles in some cases. You can raise it by mixing baking soda and water together. (established trees/not rec)
What are the soils like locally here in SD
Generally the soils we have are alkali and high in salts. This is because we are in a semiarid area where we do not get sufficient rainfall to promote leaching away the salts.
What is the rhizosphere
the zone of intense biological activity near the actively growing roots. As roots extend through the soil, the root caps and external layers are sloughed off and materials from the roots are released into the soil.
This is a constant source of organic matter on which microorganisms feed
What is Mycorrhizae
live in a symbiotic relationship with the roots.This means that the fungi and roots both benefits from the relationship. The roots provide a place for the fungi to live, and provide food. The fungi increases the roots’ ability to absorb water and essential elements, especially phosphorus
What are some test for soil analysis
Professional Soil and pH testing-
A cheap moisture meter- to check moisture ( Amazon 7-8 bucks
Soil probes- short and long handle probes
Shovels-
Hand trowel-
Hang snake test-
Store soil tests-
Jar Test-
Nutrient Cycle from plants and Animals
Ex: Grey wolf
Killed in the 1930’s- forest began to decline
Returned in 1995- forest began to recover
Deer population came down (no wolf predator) and decomposed providing proteins to forest , both prairies/forests recovered
Willow tree saplings recovered (deer overgrazing, eating them)
Beaver population spiked ( because saplings/food became more available)
Beavers made dams that allowed mature/juvenile salmon to find rest and refuge from predators.
Local salmon recovered, fed more bears
More dead fish carcass fed the forest ( nitrogen )
Benefits of salmon for trees
50-70 percent of the nitrogen was coming from salmon. Spawning salmon and carcasses from salmon discarded by bears throughout the forest showed up as N-15 ( Nitrogen 15) in DNA tests run on the forest trees
Types of Nutrient Cycling
Compost- What’s in Compost?
Mulch- What’s in Mulch?
Leaves- leaf them alone, don’t rake them up, use them.
Weeds or grass cuttings- compost them or throw it back into beds or under trees/plants ( except noxious weeds)
Fruit and plant waste- I throw all citrus waste back under citrus trees to decompose, nature does it, why not us?
Throw it all together and see what happens! ( probably compost)
