Soil Lab Notes

Importance, Formation, Properties & Nutrients

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*What are hazards to healthy soil & how can these occur?

*Guiding Questions…write these down!

*What is the process of soil formation?

*What nutrients are in healthy soil & what do nutrients provide to plants?

*Why is soil important?

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Key Soil VocabularyDead Zone – an area of a lake, sound or ocean that has very low, or no, oxygen, causing marine life to die.Micro organisms in soil – bacteria, fungi & tiny creatures called protozoa. Macro organisms include worms, insects, etc.Nutrients – Chemicals organisms need to get from the environment to build new cells & make internal processes work (like building DNA, digestion, make leaves). Key plant nutrients are “NPK” or Nitrogen, Phosphorus & Potassium.Organic Matter – matter from living or once living plants, animals and other creaturespH – A measure of how acid or basic a solution is. In the pH scale acids have numbers from pH 0 to before 7 with 0 being the strongest acid. 7 Is pH neutral. Higher numbers, above 7 to 14 pH are basic, with 14 being the strongest base. Soil Erosion – constant wearing away (weathering) & transport of the top layers of the soil to valleys, rivers, & the oceanSoil Formation – creation of soil by breaking down rocks, minerals, & adding water, decaying plants, animals & other once living creatures

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Vocabulary (continued)Soil Layers or Horizons - There are 4 layers, or horizons, of soil in the PacNW: Nutrients & water flows, or “percolates” downward through the layers. Plants take up the nutrients if able. The rest flows down & sideward to the water table.

“O” layer (also “Litter” or “Humus” layer) – Upper layer with lots of dead, decaying plants & animals. Living creatures (fungi, bacteria, worms and small insects) consume this layer & return nutrients back to the forest plant’s roots. Once decayed, the bottom of this layer becomes part of the A layer. Generally darker brownish color.

“A” Layer, or Horizon (also “Topsoil”) - Layer rich in nutrients, decaying material, & microorganisms. Darker color. “B” Layer, or Horizon – Less humus, less nutrients andless decaying material, but has more small rocks. Lighter in color.. “C” Layer, or Horizon – Rocky, low nutrients , big rocks, part of Earth’s outer layer. Lighter, can be bedrock color.

Soil Sealing – Covering of soil by roads, houses, parking lots etc. thus not allowing forests or crops to grow. Weathering – breakdown of the outer rocky part of the Earth into smaller particles like sand, clay & minerals

Physical – weathering or breakdown of rocky areas by wind, waves & rock to rock impact

Chemical – weathering or breakdown of rock by contact with acids & bases.Biological – weakening & breakdown of rock by plants, animals and microbes

• Is a growing medium for plant (food) production– Plants provide food and oxygen for animals

• Provides habitat for billions of animals & decomposers– Animals provide food– …Used by humans for foundations, holding ponds, roads, etc.

• Acts as water filter, controls water flow & stores water• Recycles nutrients, absorbs & neutralizes contaminants• Provides most antibiotics used to fight diseases• Soil Nutrients wash into sea & fertilize the phytoplankton.

– Phytoplankton are the basis of all oceanic food chains & make about 70% of the worlds oxygen!

*Why is soil important to all living things?

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Soil Makes up the outermost layer of the Earth

Soil is formed from rocks and decaying plants and animals.

• Created by physical, chemical & biological weathering of rocks.

• Microorganisms breaking down organic matter in the soil.

Average sample composed of: • 45 percent minerals • 25 percent water• 25 percent air • 5 percent organic matter. It takes a long time to make soil. • can take over 500 years to make 2 centimeters of topsoil.

*Where does soil come from?

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Soil Composition

Figure 1. Soil composition for average soils.

Water

Minerals

Organic Matter

Air

25%

25%

45%

5%

matter from living or once living plants, animals and other creatures

Physical (mechanical) WeatheringThe breakdown of rocks by physical processes with no change in the rock’s make up.

Creates joints in rocks

Chemical Weatheringis the breakdown of rocks caused by a change in the rock’s chemical make up

Biological Weatheringthe weakening & breakdown of rock by plants, animals and microbes.

Plant Roots - can exert stress or pressure on rock. This is a biologically caused physical action.

A Lichen is made of a fungi & an algae. The Fungi release chemicals, breaking down rock minerals. The minerals released from rock are consumed by the algae.

Plant roots or microorganisms produce organic acids which help to dissolve minerals.

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Soil Formation

Weathering• Physical, Chemical and

Biological Processes break down rock.

Erosion• Broken down rock is moved

by wind, water, or ice. This breaks the rock down more!

Deposition• Sediment forms.

Organic material is added & soil begins to form

Soil TypesFigure 2. The three main soil types.

SandSmall rock &

mineral particles

0.5 – 2 mm Silt Small, fine

mineral particles

2 – 50 microns Clay

Very Small fine rock particles

< 2 microns

The % of each soil type in a soil sample will determine that soil’s

characteristics

Side note: What’s an Micron?

What are the layers in healthy soil?

• This is a cut away of a Grassland soil. It shows the different oils horizons, or layers

• Most “evolved layer”,

is the A horizon, or “Topsoil”.

• There are 4 soil horizons on top of bedrock in this image

*What are the layers in healthy soil?

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*What are hazards to healthy soil?

Erosion

Pollution

Soil Sealing

Cutting down forests

Poor Farming Practices

Overgrazing

ConstructionDust Bowl Videohttp://www.youtube.com/watch?v=1_nG9LX0Ioo&feature=related

These “degrade” the soil.

What Caused the Dust Bowl?

Dust Bowl Videohttp://www.youtube.com/watch?v=1_nG9LX0Ioo&feature=related

What Caused the “Dust Bowl”?• US gives each settler 4x more

land to farm• Unusual wet weather caused

settlers to think area is good for intense cultivation

• 6x more area becomes farmed

• Native grasses holding soil were removed

• Severe drought strikes in 1930’s, not abnormal…

• Wind, dried topsoil, creates huge dust storms

• Massive erosion!

Some solutions to Dust Bowl Problems…

Some areas have NEVER RECOVERED

Contour Farming Planting Windbreaks

Replanting Native Grasses Providing Farmers Expert Help

Extent of Eroded soil Worldwide

Soil Erosion is a huge global problem

Erosion always happens, but we have increased the process by poor land use!

Soil Sealing Covering soil w/roads, houses, malls, parking lots….etc.

OvergrazingToo many animals eating the vegetation!

“Dead Zone Process.Forming a Dead Zone

Normal situation

Aquatic Dead Zones

Low to no Oxygen Water meets oxygen rich waters in the Gulf of Mexico

Soil PropertiesSoil needs the proper

combination of 3 properties to support life

Physical: good soil structural characteristicsExample: Texture, Clumping, Water holding ability….

Biological: plentiful amount of decomposersExample: Bacteria and Fungi …..

Chemical: proper chemicals need to be presentExample: Macronutrients (NPK) &

Micronutrients (Calcium, Zinc, H2O) & proper pH

http://lawnaide.com/wp-content/uploads/2012/02/soil_Cultivation.jpg

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What nutrients are in healthy soil?

Leaf

Root

Stem

pHNitrogen

Phosphorous

Potassium

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Nutrients – Chemicals that organisms need to get from the environment to build new cells & make internal processes work (like building DNA, digestion, make leaves).

What nutrients does our forest soil need?

Nutrients: 3 key soil nutrients

• Nitrogen (N),• Phosphorous (P), and • Potassium (K)

pH Acid – Base balance

• Plants need the proper soil pH for best growth

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pH is a measure of how acid or basic soil or a solution is.

Nitrogen (N) “Leaf”

Greener Leaves

Faster growth

Better seedand

root production jschmied©2013

Phosphorous (P) “Root”Stronger root growth

Better flower blooms

Makes plants grow faster, less stress

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Potassium (K) “Stem”

Increases fruit set

Stronger stalks & stems

Drought resistance

Less disease & insect damage

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pH

• Why is the proper pH important to plants? – pH regulates the amount of nutrients that can be in soil. pH 7

is Neutral soil. NW Wash soil is 4 to 7 pH.

• How does this affect Washington forests?– Our rainfall & decomposition of leaves & needles make our soil

acidic. Only certain plants can stand acidic soils. – Conifers (pines, firs, cedars) grow best in acidic soils, that’s why

we have mostly conifers in the Pac NW!

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How do forest plants get nutrients?

Leaf litter, dead fall, and debris

Primary decay by fungi in PacNW

Release acids & nutrients ( lower pH)

Nutrients absorbed by roots fast, leave soil poor

http://www.sustland.umn.edu/implement/images/planting_fig1a.gif

CO2

O2 Sunlight

NPK + H20

Water

Water

Nutrients to tree

Nutrients to soil

NPK & Water

Soil pH

ThermalEnergy

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How does NW Washington forest soil lose key nutrients like NPK?

http://static.ddmcdn.com/gif/deforestation-2.jpg

http://www.turf2max.com/Soil%20Restoration/how-to-prevent-soil-erosion_files/erosion_run_off.jpg

http://www.cob.org/services/environment/restoration/images/himalayan-blackberry.jpg

4. Invasive species

1. Rainfall

2. Deforestation

3. Soil Erosion by wind and water

http://leidorf.blogspot.com/2007/08/forest-with-fog.html

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CO2

O2 Sunlight

NPK + H20

Water

Water

Nutrients to tree

Nutrients to soil

NPK & Water

Soil pH

Plants take up valuable nutrients quickly. Rain washes morenutrients out of the soil & lowersthe soil pH (increases acidity)

Decaying plants & animals Add Nitrogen, Phosphorous andPotassium back into the soil over time.

Not enough to replace all nutrients.

Phosphorous & Potassium also come from the weathering of rocks & minerals in the soil.

Nitrogen supply is limited in PacNW.Fungi is the primary decomposer releasing nitrogen. Plants also “fix” some nitrogen in plant root nodules.

PacNW forest plants rapidly takeup available nitrogen, leaving the soil nitrogen poor.

ThermalEnergy

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Average Class Soil Test Data

Data Table 1. Testing results for soil samples for Period XX

Test A Horizon B Horizon Potting Soil Garden SoilSoil pH [ 4 - 9 ] 4.5 4.5 7.5 7.5

Nitrogen (N) [ Low-High ] low low low low

Phosphorous (P) [ Low-High ] low low med med

Potassium (K) [ Low-High ] high

medium-high high high

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Fertilizers have different amounts of NPKYou can tell the amounts on the bag!

This fertilizer has 5% Nitrogen 8% Phosphorus 4% Potassium

Organic fertilizer is betterfor our planet overall. The trade off is that it sometimes costs more!

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Plants vs Humans most common Element needs

Plants HumansElement ElementCarbon CarbonHydrogen HydrogenOxygen OxygenNitrogen NitrogenPhosphorous Phosphorous

Sulfur Potassium

Sulfur

http://www.mii.org/periodic/lifeelement.html

http://www.sciencelearn.org.nz/Contexts/Just-Elemental/Science-Ideas-and-Concepts/The-essential-elements

http://www.ncagr.gov/cyber/kidswrld/plant/nutrient.htm jschmied©2013