1 Image – a soil profile Lecture #6 – Plant Nutrition and Soils

2 Key Concepts: Resources  Which are required  How they are used Essential elements  What they are  What they do Soils and soil forming factors The rhizosphere Some alternate methods to acquire nutrients

3 Resource requirements for plant growth??? Solar energyThe sun CO 2 The atmosphere O2O2 Water The soil Nutrients ?

4 Where do plants get these resources??? Solar energyThe sun CO 2 The atmosphere O2O2 Water The soil Mineral Nutrients ?

5 Where do plants get these resources??? Solar energyThe sun CO 2 The atmosphere O2O2 Water The soil Mineral Nutrients

6 Diagram – plant resource requirements and sources Image – root system of a grass

7 Plant tissue composition by weight: Fresh herbaceous tissue is 80-85% water Little water is incorporated into plant tissue  What does water contribute to tissue??? Most water is in the cell solution, in the vacuoles, or passing through in the transpiration stream

8 Critical Thinking Does wood have such a high percentage of water???

9 Critical Thinking Does wood have such a high percentage of water??? Typically not – wood is dead tissue and xylem often becomes plugged up by resins, etc in the interior of the tree  This is what we call “heartwood” and it is often very beautiful

10 Plant tissue composition by weight: Fresh herbaceous tissue is 80-85% water Little water is incorporated into plant tissue  What does water contribute to tissue??? Most water is in the cell solution, in the vacuoles, or passing through in the transpiration stream

11 Plant tissue composition by weight: Fresh herbaceous tissue is 80-85% water Little water is incorporated into plant tissue  Water supplies all the H to carbohydrates; electrons and protons for photosynthesis Most water is in the cell solution, in the vacuoles, or passing through in the transpiration stream

12 Plant tissue composition by weight: Fresh herbaceous tissue is 80-85% water Little water is incorporated into plant tissue  Water contributes H to carbohydrates; electrons and protons for photosynthesis Most water is in the cell solution, in the vacuoles, or passing through in the transpiration stream

13 DRY plant tissue composition by weight: 45% carbon 45% oxygen 6% hydrogen 5% inorganic mineral nutrients Each a tad under 45%

14 DRY plant tissue composition by weight: 45% carbon – from ?? CO 2 45% oxygen – from ?? CO 2 6% hydrogen – from ?? water 5% inorganic mineral nutrients – from ?? soil

15 DRY plant tissue composition by weight: 45% carbon – from CO 2 45% oxygen – from 6% hydrogen – from 5% inorganic mineral nutrients – from

16 DRY plant tissue composition by weight: 45% carbon – from CO 2 45% oxygen – from CO 2 6% hydrogen – from water 5% inorganic mineral nutrients – from

17 Diagram – what goes into photosynthesis and what comes out C, H, O – source and fate in photosynthesis

18 DRY plant tissue composition by weight: 45% carbon – from CO 2 45% oxygen – from CO 2 6% hydrogen – from water 5% inorganic mineral nutrients – from soil  % of wet weight, but many are essential to plant growth and function

19 Critical Thinking What is the difference between a chemical element, a molecule and a macromolecule???

20 Diagram – structure of chlorophyll molecule Critical Thinking What is the difference between a chemical element, a molecule and a macromolecule??? N vs. N 2 vs. chlorophyll

21 Essential Elements Chemical elements  Not molecules, though some are delivered in that form – N vs. NO 3 - Required for growth and function of the plant Can’t be replaced by some other element Some contribute to structural components Some contribute to metabolic processes or the maintenance of homeostasis

22 Essential elements in structural plant components: What are some essential molecules used in structural components??? ?

23 Essential elements in structural plant components: Cellulose – ?? Lignin – ?? Pectin – ?? Cell membranes – ?? Proteins (cell membrane, cytoskeleton) – ??

24 Essential elements in structural plant components: Cellulose – C, H, O Lignin – C, H, O, S Pectin – C, H, O, Ca Cell membranes – C, H, O, P Proteins (cell membrane, cytoskeleton) – C, H, O, N, sometimes S Note – C H and O are in ALMOST ALL organic molecules

25 Essential elements for metabolic processes: What are some essential molecules used in metabolic processes??? ?

26 Essential elements for metabolic processes: Chlorophyll – ?? Nucleic acids – ?? ATP – ?? Enzymes and other proteins – ?? Enzyme cofactors – ?? Elements that control water, charge and solute balance – ??

27 Essential elements for metabolic processes: Chlorophyll – C, H, O, N, Mg Nucleic acids – C, H, O, N, P ATP – C, H, O, N, P Enzymes and other proteins – C, H, O, N..S Enzyme cofactors – many micronutrients Elements that control water, charge and solute balance – K, Cl, P, Ca, others Note – C H and O are in ALMOST ALL organic molecules

28 Macro Nutrients vs. Micro Nutrients Nitrogen Potassium Calcium Magnesium Phosphorous Sulfur Chlorine, Iron, Boron, Manganese, Zinc, Copper and Molybdenum Some plants also require Nickel, Sodium, Silicon, Selenium or others mass All used in large quantities to support the structures and processes listed before Mostly used in enzymes, as enzyme cofactors or in electron transfers – often reused, less required

29 Table – essential nutrients, both macro and micro Study table in book!

30 Memory device in honor of my friend and mentor, Dr. Chuck Davey – celebrated in 2006 for 50 years of service to soil science!!! “C HOPKNS CaFe, Mg, Mn B CuZn Mo, Cl” C. Hopkin's cafe, mighty good, managed by cousin Mo, waitress Clara Nickel may also be essential

31 Images – various plants that use additional elements Silicon in horsetails Sulfur in mustards Uranium in macadamia nuts Some minerals required, some by chance…

32 Critical Thinking How do you tell which are required???

33 Diagram – a hydroponic experiment Critical Thinking How do you tell which are required??? Hydroponics!

34 Critical Thinking How do you tell which are required??? Hydroponics! How would elements NOT required enter the plant tissue???

35 Critical Thinking How do you tell which are required??? Hydroponics! How would elements NOT required enter the plant tissue??? They are pulled toward the root in the transpiration stream, and enter through any membrane channel they can fit through

36 Images – signs of deficiency All plants will exhibit signs of deficiencies…..

37 Critical Thinking If the deficiency appears first in the older leaves, is that nutrient mobile or immobile???

38 Critical Thinking If the deficiency appears first in the older leaves, is that nutrient mobile or immobile??? Mobile – it’s being translocated from the older tissues to the new, growing tissues How???

39 Critical Thinking If the deficiency appears first in the older leaves, is that nutrient mobile or immobile??? Mobile – it’s being translocated from the older tissues to the new, growing tissues How??? In the phloem!!!  The older tissue acts as a source  The younger tissue is the sink

40 Mg deficiency in older leaves (mobile) Fe deficiency in younger leaves (immobile)

41 Critical Thinking Why would some elements be mobile, and others not???

42 Critical Thinking Why would some elements be mobile, and others not??? Must be soluble in water – phloem sap is water based… Some get locked into membranes or other components that can’t be broken down

43 Image – roots Most plants get most of their nutrients from the soil – absorbed through the roots

44 Soil is not just Dirt! Soil is the “skin” of the earth Soil provides for virtually all our food Soil supports the forests that maintain the hydrological cycle Soil supports virtually all terrestrial ecosystems – from micro-organisms to charismatic macro-fauna

45 Image – erosion after tropical deforestation The results of deforestation are ecological, economic and social disaster ( ) Rosie

46 Removing the plants removes the soil’s protective “blanket” and erosion is almost inevitable

47 More images – erosion Erosion from deforestation in Madagascar

48 Image – sediments from eroded land flooding out to sea Sedimentation from erosion – this represents a huge loss of soil “capital”

49 Image – sediments eroding off Haiti into the sea Sediments eroding off Haiti

50 Image – the political boundary is clear from the deforestation Haiti Dominican Republic

51 Image – the drought in Haiti, where residents eat mud to survive Haiti’s drought is caused largely by deforestation – the hydrological cycle has been snapped

52 Maps – deforestation in England and in the US Deforestation in Warwickshire, England Deforestation in the US

53 Map – soil loss in the Southern Piedmont of the US due to deforestation and abusive agricultural practices Piedmont soil erosion in the southeastern US

54 Image – eroded land in the Southern Piedmont The USFS Calhoun Experimental Forest in the 1950’s Union County, South Carolina

55 Maps – loss of farms, rise of industrial forestry, creating the biological deserts of pine plantations Loss of soil (along with the boll weevil) nearly eliminated productive agriculture in the Southern Piedmont after the 1920’s – now most of the Piedmont is in industrial pine plantations because it can no longer support productive agriculture

56 Social Justice You can help!!!

57 Compassionate Thinking What can you do to help???

58 Compassionate Thinking What can you do to help??? Give – time, money Conserve – resources Learn Think Talk Activate – take leadership roles VOTE!!!!! There are 3 R’s

59 Soil: A dynamic natural body in which plants grow, composed of mineral and organic materials, air, water, and living organisms

60 Soil: A dynamic natural body in which plants grow, composed of mineral and organic materials, air, water, and living organisms

61 Soil: A dynamic natural body in which plants grow, composed of mineral and organic materials, air, water, and living organisms

62 Soil: A dynamic natural body in which plants grow, composed of mineral and organic materials, air, water, and living organisms

63 Soil: A dynamic natural body in which plants grow, composed of mineral and organic materials, air, water, and living organisms

64 Soil: A dynamic natural body in which plants grow, composed of mineral and organic materials, air, water, and living organisms

65 Soil: A dynamic natural body in which plants grow, composed of mineral and organic materials, air, water, and living organisms

66 Soil: A dynamic natural body in which plants grow, composed of mineral and organic materials, air, water, and living organisms

67 Soil: A dynamic natural body in which plants grow, composed of mineral and organic materials, air, water, and living organisms

68 Soil: A dynamic natural body in which plants grow, composed of mineral and organic materials, air, water, and living organisms

69 Soil Forming Factors: Parent Material Climate Living Organisms Topography Time All soil forming factors interact!!!

70 Parent Material The substrate from which soil forms May be bedrock or some deposited material (sediments, organic material…) Determines soil texture, mineral content Influences soil structure and pH

71 Igneous rocks form from molten rock Sedimentary rocks form from deposited materials

72 Metamorphic rocks form from igneous or sedimentary rocks that have been altered by heat and pressure

73 In the Charleston area, our soils form from unconsolidated Coastal Plain sediments

74 Critical Thinking Why???

75 Critical Thinking Why??? We were under water from ~ 140 mya to less than 100,000 years ago

76 Sediments were deposited on top of the crystalline bedrock during all this time Soil develops from what’s on top!

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78 PM determines soil texture = percentage of sand, silt and clay Loam soils have ~ equal percentage of each texture class

79 CLAYCLAY

80 Clays are especially important Tiny (<2um)  Huge surface area per unit mass (1000X more than same volume of sand) Typically platy in structure = vast additional internal surface area (800 m 2 /gm) Typically clay minerals carry a negative charge

81 Critical Thinking Why is a huge surface area of negative charge important to soil fertility???

82 Critical Thinking Why is a huge surface area of negative charge important to soil fertility??? Many essential elements are in the soil solution in cation form  Clay particles hold these cations and limit leaching Water is also held (remember it’s polar)  Plus, smaller pore size holds more water

83 Most clays carry negative charge on both external and internal surfaces

84 Cation Exchange – remember the root cap – protons displace cations

85 Texture also influences soil moisture – clays hold onto more water Small pore size and negative charge Relationship between soil texture, field capacity and water availability

Hands On Determine soil texture Take some soil from your jar and dampen slightly – use the flow chart Mix the soil with your hands – can you make a firm ball of soil??? Can you make a ribbon of clay with your fingers??? Rub a bit of soil between your fingers – can you feel the grit of sand??? The powder of silt and clay??? 86

Hands On Add water to your jar and shake  Have a ruler ready Set the jar down and mark the time  Measure sediments after 40 seconds = sand  Measure again at 30 minutes = sand + silt  Remainder is clay – we may have to wait until tomorrow to get final measurements  Divide the depth of each layer by the total to get percentage of sand, silt and clay  Use textural triangle to determine soil texture 87

88 Parent materials are weathered by other soil forming factors to form soil

89 Soils are typically layered, in horizons, because of downward movement of water, clays, etc

90 Critical Thinking Which soil horizon has the most biological activity??? Why??? OABCOABC

91 Critical Thinking Which soil horizon has the most biological activity??? The “A” horizon – the topsoil Why??? More air, water and organic materials from the surface

92 “A” Horizon The topsoil is the most biologically active horizon – more air, water and organic materials from the surface

93 Soil Profile – a cut that reveals the horizons

94 Climate Primarily temperature and precipitation patterns Temperature controls freeze-thaw cycles that contribute to physical weathering Temperature also affects the rate of biochemical reactions Temperature also affects the rate of decomposition by fungi, bacteria, and other living organisms

95 Climate Precipitation contributes to soil moisture, which affects plant growth and the activity of decomposing organisms Precipitation affects erosion (the physical loss of soil particles) and leaching (chemical losses from the soil solution as water passes through the soil – this contributes to profile formation)

96 Major biomes are determined by climate – microclimate is also important in soil development

97 Living Organisms Macro-organisms, including plants and animals Micro-organisms, including bacteria, fungi, single-celled “protists”, and micro-fauna Human activity typically results in abrupt and very negative changes to soil

98 Living Organisms – Plants Contribute organic material – both from above (shoots) and below (roots), and both sources affect horizonation Help to mix the soil – root channels, wind throws Cycle nutrients from soil to plant and back (sometimes through animals, always through decomposers) Help prevent soil erosion by breaking the force of rain, providing a litter layer

99 Same parent material will develop into a different soil under different plant communities

100 Critical Thinking Why are grassland soils so dark at the surface???

101 Critical Thinking Why are grassland soils so dark at the surface??? Organic material! Grasses have a lot of fine roots and very quick root turnover A lot of OM is contributed

102 Living Organisms – Animals Contribute organic material when they die Contribute to nutrient cycling Help to mix the soil by burrowing, some even “eat” soil (earthworms)

103 Critical Thinking How do animals contribute to nutrient cycling???

104 Critical Thinking How do animals contribute to nutrient cycling??? Plants absorb nutrients from the soil Animals turn plant into animal Dead animals (plus “excess” biomass) return those nutrients to the soil via decomposing fungi, bacteria, etc Plants absorb nutrients from the soil…

105

106 Living Organisms – Micro-orgs Decompose organic material, cycle nutrients, add OM Trillions/kg of soil (double handful of soil….) N-fixing bacteria = supply virtually all N for plant growth, either free living or in nodule  the nitrogen paradox….bacteria convert atmospheric N to forms suitable for plant uptake Mycorrhizae = mutual symbiotic association between fungi and roots, present in most plants, required by some

107 Small animals, soil dwelling micro-fauna, fungi, bacteria, and other micro-organisms decompose dead OM, cycling nutrients back into the soil

108 Living Organisms – Micro-orgs Decompose organic material, cycle nutrients, add OM Trillions/kg of soil (double handful of soil….) N-fixing bacteria = supply virtually all N for plant growth, either free living or in nodule  The nitrogen paradox….bacteria convert atmospheric N to forms suitable for plant uptake Mycorrhizae = mutual symbiotic association between fungi and roots, present in most plants, required by some

109 N-fixing bacteria in symbiotic mutualisms, mostly with legumes

N-fixing bacteria in trees! Mosses on old-growth trees in the coastal Pacific Northwest forests host significant populations of N-fixing cyanobacteria Rain washes the nitrogen into the soil Trees absorb from soil Trees > 100 years old  Must be old for moss Published

111 Living Organisms – Micro-orgs Decompose organic material, cycle nutrients, add OM Trillions/kg of soil (double handful of soil….) N-fixing bacteria = supply virtually all N for plant growth, either free living or in nodule  the nitrogen paradox….bacteria convert atmospheric N to forms suitable for plant uptake Mycorrhizae = mutual symbiotic association between fungi and roots, present in most plants, required by some

112 Critical Thinking What do you think mycorrhizae might contribute to the symbiosis???

113 Critical Thinking What do you think mycorrhizae might contribute to the symbiosis??? Surface area – LOTS

114 Mycorrhizae are symbiotic mutualisms between fungi and plants – fungal hyphae vastly increase surface area for water and nutrient absorption – 85% of plants depend on them

Hands On Shake up class sample of soil / water to mix Examine a drop of soil “solution” for microorganisms 115

116 Living Organisms – The human impact Removing vegetation dramatically increases erosion, cultivation exacerbates Deforestation can snap hydrological cycles Excessive fertilizer and pesticide use contaminates both soil and water Improper irrigation salinates soil Wetland drainage damages wetland soils and on….

Topography – the shape of the land 117

118 Topography – the shape of the land Determines the movement of water, thus affecting erosion and leaching rates Determines where water accumulates, which affects soil moisture, which affects organismal activity, which affects soils…. Aspect affects the amount of solar radiation at the surface, and thus soil temperature Large topographic features influence precipitation patterns Even micro-topography influences plant distribution

119 Topographic Aspect – red and blue face S and W; green and yellow face N and E

120 Critical Thinking Why are the north and east slopes of a hill cooler???

121 Critical Thinking Why are the north and east slopes of a hill cooler??? The hill itself shades those sides

122 Topography – the shape of the land Determines the movement of water, thus affecting erosion and leaching rates Determines where water accumulates, which affects soil moisture, which affects organismal activity, which affects soils…. Aspect affects the amount of solar radiation at the surface, and thus soil temperature Large topographic features influence precipitation patterns Even micro-topography influences plant distribution

123 Orographic lifting makes it rain

124 Critical Thinking What the heck is orographic lifting and why does it cause rain???

125 Critical Thinking What the heck is orographic lifting and why does it cause rain??? Orographic means that an air mass is being forced by wind to go up and over a mountain

126 Critical Thinking What the heck is orographic lifting and why does it cause rain??? Orographic means that an air mass is being forced by wind to go up and over a mountain The air mass cools at higher elevations, condenses, and precipitation falls

127 Orographic lifting causes cooling and precipitation, rain shadow to the leeward

128 Topography – the shape of the land Determines the movement of water, thus affecting erosion and leaching rates Determines where water accumulates, which affects soil moisture, which affects organismal activity, which affects soils…. Aspect affects the amount of solar radiation at the surface, and thus soil temperature Large topographic features influence precipitation patterns Even micro-topography influences plant distribution

129 Small change in elevation… …big change in the plant community! Images showing pond embedded within longleaf pine community

Hands On Let’s go outside for this one…. Trays of soil at different slopes to demonstrate erosion x slope + erosion vs. leaching Pour water from same height and at same rate on different slopes 130

131 Time…. The length of time all these factors have been acting determines the characteristics of the soil The same parent material will develop different soils as time passes Major component of primary succession

132 Soil development on glacial till

133 Soil Forming Factors: Parent Material Climate Living Organisms Topography Time Remember – all soil forming factors interact!!!

134 The Rhizosphere The area of interaction between root and soil. A huge volume of soil, but a very narrow zone

135 The rhizosphere is the zone of cation exchange, nutrient and water uptake

136 The Rhizosphere Complex zone with many interacting factors Plant affects soil through compounds secreted by the plant’s roots Relative proportions of nutrients in the soil solution can affect uptake of all nutrients Also, different species have different nutrient requirements Rhizosphere is the control zone for plant/soil interactions

137 Some plants use alternate methods to absorb some nutrients Parasites, saprophytes, carnivores

138 Key Concepts: QUESTIONS??? Resources  Which are required  How they are used Essential elements  What they are  What they do Soils and soil forming factors The rhizosphere Some alternate methods to acquire nutrients

Hands On What can you tell from this data??? 139

Extra Credit Putz around on the USDA soils site college/index.htmlhttp://soils.usda.gov/education/resources/ college/index.html 140