1. Welcome to the 2004 Massachusetts Envirothon Workshop Part II
Soils Overview Workshop
Part II
Tom Cochran
USDA-NRCS Franklin Co., MA
Some material courtesy of Jim Turenne
USDA-NRCS, Rhode Island
Intro
Into Give thumbnail of duties.

2. Climate
Rain water allows chemical reactions to occur on the exposed surfaces of the minerals that compose the rock.
Some of the elemental molecules leave the surface of the minerals and go into solution. (i.e. iron, calcium, magnesium, aluminum, potassium, etc.)
This weakens the crystal structures of the rocks and particles begin to break off, and cracks begin to form in the rock matrix. The particles and the minerals in solution begin to form the soil.
Effects of rainfall on rock weathering.

3. Climate (continued) Temperature also affects soil forming process.
When rain water enters the cracks and freezes, the water expands with enough force to fracture the bedrock, forming boulders, stones, and/or cobbles.
Prolonged cold temperatures slow organic matter decomposition causing an increased percentage of soil organic matter.
Saturated conditions also slow the decomposition process.
In western Massachusetts, we get approximately 40 inches of rainfall per year.
There are 80  130 frost-free days in the Berkshire Mts., and 150-> 195 frost-free days in the Connecticut River Valley.
Temp & rainfall numbers for western MA.

4. Organisms
Organisms including bacteria, fungi, earthworms, nematodes, arthropods, moles, groundhogs, man, etc. alter the soil by their actions.
One teaspoon of soil often contains millions of bacteria and fungal organisms.
These microbes decompose organic materials deposited at the soil surface and are responsible for the dark colors of the surface horizon. Without them we would be living on dead organic matter.
The by product of their respiration process is the catalyst for the formation of light colors in saturated zones of soil bodies.
Arthropods, nematodes, moles, groundhogs, and man stir the soil and promote the presence of structure in the soil body.
List of prominent organisms in the soil. Without them, we would be buried in litter. Respiration drives the formation of redoximorphic features.

5. Food web in soil courtesy of Jim Turenne.

6. Soil fungi
Bryant Slide. Fungi in a forested system. Picture courtesy of Jim Turenne.

7. Earthworm Burrows middens
Bryant Slide
Earthworm burrows and channels have an affect on infiltration. The presence of earthworm channels connected to the surface improves the infiltration rate of the field. Pictures courtesy of Jim Turenne.
Middens: piles of residue around the mouth of earthworm burrows.

8. Topography
Topography affects the water flow on and through the soil, which affects the soil formation processes.
Note water flow paths in upper drawing and series locations in lower block diagram.

9. Topography (continued)
Soil types can often be found on the landscape in a predictable pattern because of the topographic soil forming factor.
Note the parent material and possibility of catenas.

10. Time
Over time, the affects of climate, topography, and organisms continually alter the parent material and soil particles, which results in the formation of recognizable soil profiles.
It takes 500 years to form one inch of topsoil.
It takes thousands of years to form a weakly structured subsurface horizon like we have in New England.
It takes tens of thousands of years to form the well structured clay subsurface horizons of the south and mid-west.
Facts about time needed for horizon formation.

11. Soil Horizonation
Over a long period of time, the other four soil forming factors combine to create soil bodies with unique sets of horizons and characteristics.
Thousands of different soil series exist in the US and more are continually identified as new areas are mapped and old mapping projects are updated.
Each soil series has a unique set of horizons and characteristics. These horizons and characteristics are a product of soil forming processes.
Not every soil body is affected by the same soil forming processes.
Horizonation provides the initial separation of soil series. There are diagnostic characteristics that group horizons based on formation processes.

12. Soil Forming Processes
There are four processes that guide horizon formation:
Translocations – Movement of ions and compounds from horizons above to horizons below.
Transformations – Chemical and physical alteration of soil material.
Additions – Anything that is added to the soil. Organic matter, fertilizer, and ions in rain water represent additions to the soil.
Losses – Minerals, ions, and organic matter are removed from the soil profile. Leaching and erosion are the main loss processes.
USDA-NRCS Slide in “Helping People Understand Soils”.

13. The major horizons are as follows.
O = organic matter on the soil surface that is in various states of decay.
A = the surface of the mineral soil that is composed of mineral and organic material.
E = the horizon between the surface and subsurface that has some part of it removed and transported to the subsurface by the flow of precipitation through the soil. Clay, iron, aluminum, and humus are most often the materials removed.
B = the subsurface zone where materials from the horizons above are deposited by the water that continually moves down from the surface.
C = A zone of partially weathered rock.
R = bedrock in its unchanged state.
Definitions of main horizons.

14. An E horizon can develop in this area.
Sketch of typical soil profile.
Bedrock can lie below the C horizon. In this position, the bedrock is called an R horizon.

15. Soil Characteristics
Horizon characteristics are used to name and classify soil.
Soil taxonomy defines diagnostic horizons that have certain properties, which reflect the soil forming processes that created them .
There is a set of surface and subsurface diagnostic horizons.
The main clues for identifying diagnostic properties of interest include texture, color, structure, consistency, and profile position.
Your soil judging worksheet will ask you to identify the soil forming factors and the soil diagnostic features that are evident in each of the soil bodies to be judged.
The characteristics of soil horizons help us name the soils and identify the limitations to use and management the soil may present.

16. Texture
Texture is often the first characteristic soil scientists determine.
It is the relative proportion of sand, silt, & clay sized particles in the fine earth fraction of a soil horizon.
The fine earth fraction is all of the individual particles that are smaller than 2mm in diameter. Everything larger than sand is excluded. . .
Silt
Particle
Attempt at illustrating the size relation of fine earth particles.These are approximate particle size after magnification 133 times. Except the clay is still much larger than it should be million clay particles will fit in half of the sand particle.
2mm sand particle
magnified 133x
Clay particle

17. The three main methods for measuring texture are
Pipette method – laboratory procedure used by the National Soil Survey Lab in Lincoln, NE. It is time consuming and very accurate.
Hydrometer method – a reasonably accurate simple laboratory procedure often used in soil survey field offices to test the accuracy of the feel method.
Feel method – method used by soil scientists in the field, which involves feeling the soil with your fingers.
Requires practice and occasional calibration with the hydrometer method .
Soil survey scientists continually compare how they perceive various field samples using the feel method. This ensures consistent results from one scientist to another.
Methods used to determine texture.

18. Flow chart for the feel method.

19. Textural triangle showing the 12 main textural classes.