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1 © 2011 Regents of the University of Minnesota. All rights reserved. 11 The Dirt on Dirt PART ONE – UNDERSTANDING SOIL Presenter’s Name Presenter’s Title.

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Presentation on theme: "1 © 2011 Regents of the University of Minnesota. All rights reserved. 11 The Dirt on Dirt PART ONE – UNDERSTANDING SOIL Presenter’s Name Presenter’s Title."— Presentation transcript:

1 1 © 2011 Regents of the University of Minnesota. All rights reserved. 11 The Dirt on Dirt PART ONE – UNDERSTANDING SOIL Presenter’s Name Presenter’s Title Presenter’s Organization

2 2 © 2011 Regents of the University of Minnesota. All rights reserved. SOIL QUALITY (SOIL HEALTH)  The ability of the soil to “function”  An indicator of environmental health

3 3 © 2011 Regents of the University of Minnesota. All rights reserved. FUNCTIONING DEFINED  Plant growth –Fertile –Good rooting environment –Water holding capacity without saturating

4 4 © 2011 Regents of the University of Minnesota. All rights reserved. FUNCTIONING DEFINED  Environmental Health –Resists erosion –Holds nutrients (preventing them from ending up in ground and/or surface water) –Supports a biological community

5 5 © 2011 Regents of the University of Minnesota. All rights reserved. FARMERS DESCRIBE SOIL HEALTH  Deeper and darker topsoil  Easier to till  Absorb and hold more water  Become trafficable sooner after rain  Higher organic matter and less erosion  Have more earthworms  Sweet “earthy” smell

6 6 © 2011 Regents of the University of Minnesota. All rights reserved. FARMERS DESCRIBE THE BENEFITS OF A HEALTHY SOIL  Less fuel cost  Less wear and tear on machinery  Less fertilizer required  Higher yields  Fewer problems with insects and disease  Better feed quality of crops produced

7 7 © 2011 Regents of the University of Minnesota. All rights reserved. MOVING FORWARD  Soil Quality is a combination of factors you can and can not control  By understanding the basics of Soil Science you can view them through a “Soil Quality” lens

8 8 © 2011 Regents of the University of Minnesota. All rights reserved. WHAT WE WILL COVER  What is soil?  How was the soil formed?  The chemistry of soil

9 9 © 2011 Regents of the University of Minnesota. All rights reserved. WHAT IS SOIL?  Four Parts –Mineral –Water –Air –Organic

10 10 © 2011 Regents of the University of Minnesota. All rights reserved. THE MINERAL FRACTION  Classified by size –Sand – you can see sand, if it were the size of a minivan –Silt – would be the size of a basketball –Clay – would be the size of a quarter (and clay particles are flat too!)  Texture is the percentage of each  Finer textured (more clay) soils can hold more soil organic matter

11 11 © 2011 Regents of the University of Minnesota. All rights reserved. IF IT IS NOT SOLID  It is pore space –made up of air, or –filled with water  When the pores are all filled with water they are saturated or “at field capacity”  At this point all air (and therefore oxygen) is excluded

12 12 © 2011 Regents of the University of Minnesota. All rights reserved. SOIL WATER  Water can not be completely removed, but  At a low volume it is not available to a plant  When in excess it ponds, runs off, or leaches from the system

13 13 © 2011 Regents of the University of Minnesota. All rights reserved. ORGANIC MATTER  Is present in the soil in varying states of decomposition  Decomposed organic matter is dark, and therefore gives the soil its dark color  A portion of soil organic matter is alive

14 14 © 2011 Regents of the University of Minnesota. All rights reserved. WHAT IS ORGANIC MATTER?

15 15 © 2011 Regents of the University of Minnesota. All rights reserved. AS YOU GO DEEPER  The soil has less organic matter, and therefore is lighter in color  Many people identify this sub-soil as “clay”  Clay is a texture, not a color

16 16 © 2011 Regents of the University of Minnesota. All rights reserved. So when you look at the soil… AND SOIL IS SO FUN TO LOOK AT…

17 17 © 2011 Regents of the University of Minnesota. All rights reserved. YOU SEE:

18 18 © 2011 Regents of the University of Minnesota. All rights reserved. THE SOIL PROFILE  Refers to the layers of soil going from the top down  The topsoil is the A Horizon  Followed by the B Horizon (transition zone)  Then the C Horizon (subsoil)

19 19 © 2011 Regents of the University of Minnesota. All rights reserved. WHY IS THE PROFILE IMPORTANT?  Visual evidence of various properties  Used to describe the specific soil at any given site  The trained eye may be able to pick out much more

20 20 © 2011 Regents of the University of Minnesota. All rights reserved. Why are there differences? What does it mean?

21 21 © 2011 Regents of the University of Minnesota. All rights reserved. HOW THE SOIL WAS FORMED THE SOIL FORMING FACTORS  Parent Material  Relief  Time  Biological History  Climate

22 22 © 2011 Regents of the University of Minnesota. All rights reserved. PARENT MATERIAL  All mineral matter originated from a rock somewhere  Where did it come from?  How did it get here? –Glaciers (till soils) –Wind blown (loess) –Sediment deposited by water

23 23 © 2011 Regents of the University of Minnesota. All rights reserved. PARENT MATERIAL CAN AFFECT  Fertility  Water Infiltration  Texture All the soil forming factors work together on properties of the soil

24 24 © 2011 Regents of the University of Minnesota. All rights reserved. RELIEF  Erosion is a natural process - expect deeper topsoil at the bottom of the hill  Landscape can affect other soil forming factors like climate and biological history

25 25 © 2011 Regents of the University of Minnesota. All rights reserved. TIME  There are probably not any significant differences in any area with respect to major soil forming factors (glaciers, etc.)  More likely that time since major alteration is a factor –Farming history –Drainage –Construction or physical alteration

26 26 © 2011 Regents of the University of Minnesota. All rights reserved. TIME CAN CAUSE  Loss of soil organic matter  Subsidence in low areas  Increased total rates of erosion on farmed landscapes  Changes in soil properties based on crop, tillage, and fertility history

27 27 © 2011 Regents of the University of Minnesota. All rights reserved. BIOLOGICAL HISTORY  Major soils classifications based on: –Prairie (Mollisols) – Our dark “black” soils –Hardwood forest (Alfisols) – Dark brown, shallower topsoil, often have a clay layer –Young soils from altered landscapes (Entisols) - Sediment often characterized by a lack of biological history –Swamps and wetlands (Histosols) – Frequently referred to as peat

28 28 © 2011 Regents of the University of Minnesota. All rights reserved. BIOLOGICAL HISTORY  Our prairie soils had 6% - 8% soil organic matter at the time of settlement  This has decreased to around 3% in most farm fields  Alfisols had less  Most “peat” ground that has been drained has been decomposing and subsiding due to weathering and oxidation (reduction from 20% + organic matter to around 10% or less)

29 29 © 2011 Regents of the University of Minnesota. All rights reserved. BIOLOGICAL HISTORY  On a smaller scale soil properties are affected by: –Gophers, badgers, prairie dogs, etc. –Ants and other insects –Earthworms (which probably are not native) –Fungus –Microbiology (like algae, bacteria, etc.)

30 30 © 2011 Regents of the University of Minnesota. All rights reserved. CLIMATE  Few differences in any given area –Some related to Hillside exposure (North vs. South) –Proximity to water (may be warmer)

31 31 © 2011 Regents of the University of Minnesota. All rights reserved. This all leads to…………..

32 32 © 2011 Regents of the University of Minnesota. All rights reserved. Soil Classification

33 33 © 2011 Regents of the University of Minnesota. All rights reserved. SOIL CLASSIFICATION  The soil survey, and all those maps and descriptions  What is the name of your favorite soil?  If nothing else, you have always wondered what this means!

34 34 © 2011 Regents of the University of Minnesota. All rights reserved. THE SOIL SURVEY  All soils with the same name have the same qualities  The info in “the front of the book” interprets the names  Now the WebSoilSurvey has a user friendly interface for finding all this out

35 35 © 2011 Regents of the University of Minnesota. All rights reserved. WHAT YOU CAN FIND OUT  Limitations –Depth to bedrock –Depth to water table –Extensive erosion and other misc. problems  Ratings and capabilities –Agriculture and forestry –Development –Engineering

36 36 © 2011 Regents of the University of Minnesota. All rights reserved. SOME INHERENT SOIL CHEMICAL PROPERTIES  Cation Exchange Capacity (CEC)  pH  Native levels of nutrients  Texture – can give some indication on the chemical “needs”

37 37 © 2011 Regents of the University of Minnesota. All rights reserved. Which leads us to a conversation about…….

38 38 © 2011 Regents of the University of Minnesota. All rights reserved. Soil Chemistry

39 39 © 2011 Regents of the University of Minnesota. All rights reserved. Lets start with…..

40 40 © 2011 Regents of the University of Minnesota. All rights reserved. CLAY- YOUR FRIEND AND MINE  Clay particles are flat and plate like  They are more like a sheet that has been broken into bits  These “broken” edges have negative charges associated with them  The negative charges attract positive ions such as potassium and calcium – plant nutrients

41 41 © 2011 Regents of the University of Minnesota. All rights reserved. YOU MAY THINK CLAY IS BAD, BUT YOU ARE WRONG!  Clay provides a large percentage of the inherent fertility in soil  Clay slows water infiltration, increasing water holding capacity and preventing the leaching of many nutrients

42 42 © 2011 Regents of the University of Minnesota. All rights reserved. SOIL FERTILITY  Some levels of nutrients are present “natively” in the soil – this varies based on parent material  Nutrients cycle in the environment via natural processes  Natural “build-up” of fertility is very slow  Removal through crop harvest will cause depletion very fast

43 43 © 2011 Regents of the University of Minnesota. All rights reserved. Similar to Soil Fertility, but not the same….

44 44 © 2011 Regents of the University of Minnesota. All rights reserved. SOIL pH  Remember 7.0 is neutral – the pH of water  Lots of water percolating through the soil tends to lower pH (acid)  High pH (alkaline) soils are often found in drier climates  Certain types of biological history can lead to either high or low pH

45 45 © 2011 Regents of the University of Minnesota. All rights reserved. THERE ARE MANY OTHER ASPECTS OF SOIL CHEMISTRY  Salinity  Sodic places  Toxic levels of heavy metals  And more Tend toward extreme circumstances and/or climates outside of our region

46 46 © 2011 Regents of the University of Minnesota. All rights reserved. ARE YOU SMARTER THAN WHEN WE STARTED?  If nothing else we laid the foundation for the next section So, to tease the next segment:

47 47 © 2011 Regents of the University of Minnesota. All rights reserved. PART 2 WILL COVER THE DISCIPLINES WITHIN SOIL SCIENCE  Chemistry and Fertility – we talked about this already, but we will go into more detail  Biology – the life within the soil  Physics – Water, temperature, compaction And to leave one departing nugget of Soil Science wisdom:

48 48 © 2011 Regents of the University of Minnesota. All rights reserved. There is no such thing as quicksand! IT’S TRUE, THAT’S JUST SOMETHING MADE UP BY HOLLYWOOD © Warner Brothers

49 49 © 2011 Regents of the University of Minnesota. All rights reserved. So at least you learned one thing! EVEN IF IT IS WORTHLESS TRIVIA

50 50 © 2011 Regents of the University of Minnesota. All rights reserved. The University of Minnesota is an equal opportunity educator and employer. In accordance with the Americans with Disabilities Act, this PowerPoint is available in alternative formats upon request. Direct requests to the Extension Store at Thank You! This product was developed with support from the Sustainable Agriculture Research and Education (SARE) program, which is funded by the U.S. Department of Agriculture — National Institute of Food and Agriculture (USDA-NIFA). Any opinions, findings, conclusions or recommendations expressed within do not necessarily reflect the view of the SARE program or the U.S. Department of Agriculture. USDA is an equal opportunity provider and employer.


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