Quiz! Brief review of Tuesday s Lab Soil Bio- and Toposequences. Soil & Plant Water Please pick up next Tuesday s Lab Agricultural Ecosystems

Transcription

1 NREM 301 Day 10 Quiz! Brief review of Tuesday s Lab Soil Bio- and Toposequences Soil & Plant Water Please pick up next Tuesday s Lab Agricultural Ecosystems

2 Coring is hard work!

3 Finally got one!

4 Sunshine makes it easy to describe colors

5 Your colleagues at camp are busy looking at soils also

6 Just like a road crew 5 supervisors, 1 worker

7 I wonder if it s time for a soils quiz back at ISU? Yes it is!

8 A 1 B Individual 1 2 C 3 a) Match the letters with numbers For the following rank letters from high to low & give brief Why b) Organic matter content c) Amount of erosion occurring d) Degree of structure development in the surface horizon

9 What are these soil features? What causes them? Individual 2

10 Name the five soil forming factors Individual 3

11 Individual 4 Last Individual Question Define: a) Aspect b) Bt horizon c) Colluvium d) Eluviation Turn in individual papers

12 Group 1 Your colleagues in Montana are sampling soils. 1. What slope position are they on? 2. Because of their slope position, describe briefly what they might see in terms of soil development and why?

13 Group 2 Last Group Question Sketch the types of horizons and relative thicknesses you would find as time increases (assume temperate forest veg. & all other factors are equal) Turn in group papers 0 Time (years) 1,000 s

14 Tuesday s Lab Reactor Woods Identify and describe soil bio- and topo-sequences (logical orders of soils that are different because of position in the landscape)

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16 Depth (cm) Bio-sequence - forest member. Hayden - developed under deciduous forest in Des Moines Lobe till Source: Aandahl 1982

17 Approximate Depth (cm) Bio-sequence - Savanna Member Lester - developed in deciduous forest prairie transition ecotone (savanna) Source: Sandor

18 Bio-sequence Prairie Member Clarion soil - Shown to 48 in Source: Sandor

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20 Landscape of toposequence: Clarion - well-drained higher soils (lighter brown tones); Webster dark, poorly-drained wet elongated soils; Okoboji dark, circular, closed depressions; Harps dark circular above Okoboji, more calcareous; Storden very light yellow tops of hills Des Moines Lobe Upland Think about the original vegetation recall your visit to Doolittle Prairie

21 Upland Soils Clarion-Webster-Nicollet Association Note: Parent materials glacial till or local alluvium Upland depressional soil sequence from center out Okoboji 6, Harps 95, Canisteo 507 Webster depressional, non-circular soil Best drained soils Clarion 138 & Storden 62 but Storden is eroded Nicollet somewhat poorly drained

22 Soil Landscape Model for Central Iowa Hayden-Lester-Storden Association Clarion-Webster-Nicollet Association Coland-Spillville-Zook Association

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24 Soil water Limiting factor for plant growth Movement = f (porosity) Moves through macrospores Held in micropores by adhesive and cohesive forces Plant must be able to extract water by producing tension

25 Properties of water Cohesion Adhesion Capillarity Surface Tension Water Molecule Unique (+ & - Charge) Capillary Rise Hydrogen Bonding

26 Capillarity & Water Uptake in Plants Water Strider Surface Tension

27 Cohesion & Adhesion in Soil Soil Particle Capillary Rise In Soil

28 Soil Ped Gravitational Water Drains in hrs Not much use to plants Plant Root Micropore Macropore

29 Gravitational Water Has Drained Water Left Held By Adhesion/Cohesion Field Capacity Water Held in Soil By Adhesion/Cohesion & Available to Plants

30 Water Left in Soil Held Too Tightly by Adhesion/ Cohesion for Plants To Use Approaching Wilting Point & End of Available Water

31 Water Left Not Available To Plants Only Hygroscopic Water Soil Now at Wilting Point

32 Kinds of Soil Water Gravitational Water pulled down through macropores by gravity not of much use to plants not around long. Field Capacity water held against gravity by forces of tension (cohesion/adhesion) readily accessible to plants Available Water roots can produce enough tension to pull water away from soil particles water enters plant Wilting Point tension at water is held so tightly that plants cannot pull it out of soil

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34 Group Activity Water is a Major Key To Ecosystem Development/Health Diagram & Explain the Movement Of Water from the Soil through A Tree and into the Air What path does it take from the soil to the atmosphere through the tree? Where does the energy come from to move the water?

35 Water Movement Through Young Root Water Movement Through Plant Water Movement Through Stem

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37 Cuticle Mesophyll Deciduous Leaf Stomates Open in response to Low CO 2 Stomates Close in response to Low H 2 O

38 Water moves up the tree along a pressure gradient in this case a negative one (tension) Pure water has a tension = 0

39 Continuous Water Column By Cohesion & Adhesion Xylem Large Macropore Gravitational Water Root Small Micropore Unavailable Water Wilting Point if that Is all that is left in the soil Larger Micropore Available Water When these are full & large ones are empty soil is at Field Capacity

40 PWP Day Night

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42 Drainage classes Excessively drained Somewhat excessively drained Well-drained Moderately well-drained Somewhat poorly drained Poorly drained Very poorly drained Permanently wet

43 Dick we ran out of time on Thursday (Sept. 18 th ) to finish this lesson; will resume Tuesday, Sept. 23).