Soil Science Basics - University Of Maryland...“Ecstatic skin of the earth”- William Bryant...

Soil Science BasicsUME Baltimore City Master Gardener Coordinator Erin Mellenthin

emelle@umd.edu

Why is soil important?

• Media for plant growth• Regulator of Water Supplies• Recycler of Raw Materials• Modifier of the Atmosphere• Habitat for Soil Organisms• Engineering Medium

“Ecstatic skin of the earth”- William Bryant Logan

“Whether we intend to modify, exploit, preserve, or simply understand the landscape, our success will depend on our knowing how soil properties relate to the environment on each site and to the landscape as a whole” – N. Brady and R. Weil

What is soil?3-phase Ecosystem Comprised of Solids, Liquids, and Gases

Solids: Mineral and Organic

Organic – Biomass (10%), Residues and by-products (15%), and humus (75%)- 2-5% by weight- Influences soil productivity, water

retention, nutrient holding

Mineral - Delineated by particle size.• The three sizes that determine soil texture

are Sand, Silt, and Clay.

Soil Texture: Sand, Silt, ClayHow do we figure this out? Aka Particle Size Analysis

Laboratory Methods:• Sieving • Particle counting• Sedimentation: with hydrometer, and

pipette methods

In the Field:• Texture by feel

OR

Soil Textural Triangle

Sedimentation Video

Pore space: Macropores and MicroporesBasic cross-section of approximately 20 mm wide of soil as a porous, biologically active mineral-organic matrix. Red arrows show non-living components while purple arrows show biological components. Large macroporesresulting from good soil structure allow adequate drainage and air entry to a soil for biological activity, while smaller mesoporesand micropores hold water at varying degree of availability for plant roots. Macrofauna such as earthworms (;2mm approximate dimension) are also very important but would occupy too much of the diagram to show.Credit: Steven Vanek, adapted from Steven Fonte.

Soil Solution vs. Water

Air in Pores

Where does soil come from?

5 Soil Forming Factors• Parent Material (in MD… Fall Line)• Climate (Precip., temperatures)

• Landscape position (slope and aspect)• Organisms (Channels, Organic Matter)

• Time

“PLOCT”

Drainage Catena

Slide by Chris Seubert, PhD

Where does soil come from?

4 Soil Forming Processes• Additions• Losses• Transformations• Translocations

Soil Horizons

• Soils are 3-D• Can be broken into

horizons by depth• Color, structure,

chemical differences

Copyright NC state Flicker https://www.warrenswcd.com/education-connection-a-blog/archives/12-2016

• Tilth: The state of aggregation of a soil especially in relation to its suitability for crop growth.

• Friable: Easily broken into smaller pieces.

Slide by Chris Seubert, PhD

Soil Structure: The formation and grouping of the soil particles into aggregates.

Aggregate stability or structure, is easily destroyed, but not easily improved.

Function of texture, organic matter and cultural practices

Improved by organic matter, plant root growth, microorganisms and earth worms.

Destroyed by frequent tillage, tilling when wet, compaction.

Slide by Chris Seubert, PhD

Drainage• Function of structure, texture

and natural water table• Improve with raised beds,

artificial drainage, or create a mini-wetland.

Color• Black soils are high in organic

matter.• Gray soils indicate poor

drainage• Red and yellow soils contain

iron

Slide by Chris Seubert, PhD

A wall of dust approaches a Kansas town in 1935 U.S. Public Health Service Reprint # 1707 , Public Health Reports vol. 50, no. 40, 10/4/1935

Slide by Chris Seubert, PhD

Effects of Dust Bowl: Dallas, South Dakota, May 13, 1936.Soil Conservation Service RG 114

Slide by Chris Seubert, PhD

Urban Soils – “Urbents” anthropic soil• What is special about Urban

Soil?• Fill – where does it come

from what is it?• High human activity –

compaction, contamination• Paved over

Soils, Nutrients, and Cycling

Rainfall simulator

Hydrologic/water cycle in Soil

Nitrogen Cycle

Phosphorous Cycle

Bound to Iron Oxides -unavailable

Soil pH and nutrient availability

Liming – Raises soil pH

Kansas State Extension

CEC – Cation Exchange Capacity

http://bio1152.nicerweb.com/Locked/media/ch37/37_06SoilToRootHair.jpg

http://blog.botanicare.com/selectivity-of-plant-nutrient-ion-uptake/

CEC- measured in cmol/kg

Soil texturing by Feel - Ribboning

Resources

extension.umd.edu/hgic extension.umd.edu/learn/ask-gardening marylandgrows.umd.edu

extension.umd.edu/mg

This program was brought to you by University of Maryland Extension

Master Gardener ProgramBaltimore City