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Page 1: Soil Chemistry. Mineral saltsMineral salts –From weathered rocks –Break down of Organic Matter (OM) –Addition of fertilizer

Soil Soil ChemistryChemistry

Page 2: Soil Chemistry. Mineral saltsMineral salts –From weathered rocks –Break down of Organic Matter (OM) –Addition of fertilizer

Soil ChemistrySoil Chemistry• Mineral saltsMineral salts

–From weathered rocksFrom weathered rocks

–Break down of Organic Matter Break down of Organic Matter (OM)(OM)

–Addition of fertilizerAddition of fertilizer

Page 3: Soil Chemistry. Mineral saltsMineral salts –From weathered rocks –Break down of Organic Matter (OM) –Addition of fertilizer

Soil ChemistrySoil Chemistry• Salt dissolves in soil solution (HSalt dissolves in soil solution (H22O) as O) as

ionic formsionic forms

• Ion: Ion: +/- charged particle+/- charged particle

• Ex: Ex: table salt = NaCl = Natable salt = NaCl = Na++ and Cl and Cl--

CationsCationsHH++

CaCa2+2+

MgMg2+2+

NHNH44++

KK++

AnionsAnionsOHOH--

ClCl--

COCO332-2-

SOSO442-2-

Page 4: Soil Chemistry. Mineral saltsMineral salts –From weathered rocks –Break down of Organic Matter (OM) –Addition of fertilizer

Soil ChemistrySoil Chemistry• Colloids: Colloids: particles of clay and O.M. particles of clay and O.M.

suspended in solutionsuspended in solution– These attract and exchange cations!These attract and exchange cations!

• Cation Exchange Capacity Cation Exchange Capacity (CEC) = (CEC) = the soil fertilitythe soil fertility

• CEC: CEC: O.M.O.M. > > ClayClay > > SiltSilt > > SandSand

Page 5: Soil Chemistry. Mineral saltsMineral salts –From weathered rocks –Break down of Organic Matter (OM) –Addition of fertilizer

Soil ChemistrySoil Chemistry• Plants absorb nutrients as Plants absorb nutrients as ionsions!!

• Sandy soils have a low CEC and Sandy soils have a low CEC and therefore cannot hold on to ions welltherefore cannot hold on to ions well

• These soils require frequent, light These soils require frequent, light applications of fertilizerapplications of fertilizer

Page 6: Soil Chemistry. Mineral saltsMineral salts –From weathered rocks –Break down of Organic Matter (OM) –Addition of fertilizer

Soil ChemistrySoil Chemistry• Soil pHSoil pH

– Relationship of HRelationship of H++ ions to OH ions to OH-- ions ions

AcidAcid H H++ > OH > OH--

NeutralNeutral H H++ = OH = OH--

BasicBasic H H++ < OH < OH-- (also called, “alkaline”) (also called, “alkaline”)

Page 7: Soil Chemistry. Mineral saltsMineral salts –From weathered rocks –Break down of Organic Matter (OM) –Addition of fertilizer

Soil ChemistrySoil ChemistryHH++ and Al and Al3+3+ produce acidic soils produce acidic soils

CaCa2+2+ and Mg and Mg2+2+ produce basic soils produce basic soils

HighHigh rainfall areas are acidic soils rainfall areas are acidic soils

LowLow rainfall areas are generally basic or rainfall areas are generally basic or neutral soilsneutral soils

Page 8: Soil Chemistry. Mineral saltsMineral salts –From weathered rocks –Break down of Organic Matter (OM) –Addition of fertilizer

Soil ChemistrySoil Chemistry

Salt build-up in low-rainfall location damages cropsSalt build-up in low-rainfall location damages crops

Page 9: Soil Chemistry. Mineral saltsMineral salts –From weathered rocks –Break down of Organic Matter (OM) –Addition of fertilizer

• Fungi most active if pH<5.5Fungi most active if pH<5.5

• Bacteria most active if pH>5.5Bacteria most active if pH>5.5

Properly nodulated legumes add Properly nodulated legumes add 55 to 300 pounds of nitrogen per acre to soil.55 to 300 pounds of nitrogen per acre to soil.

Page 10: Soil Chemistry. Mineral saltsMineral salts –From weathered rocks –Break down of Organic Matter (OM) –Addition of fertilizer
Page 11: Soil Chemistry. Mineral saltsMineral salts –From weathered rocks –Break down of Organic Matter (OM) –Addition of fertilizer
Page 12: Soil Chemistry. Mineral saltsMineral salts –From weathered rocks –Break down of Organic Matter (OM) –Addition of fertilizer

pH of various liquidspH of various liquidshousehold ammonia household ammonia 11.9 11.9

sea water sea water 8.58.5

human blood human blood 7.4 7.4

milk milk 6.4 6.4

orange juice orange juice 3.5 3.5

lemon juice lemon juice 2.32.3

vinegar vinegar 2.82.8

Page 13: Soil Chemistry. Mineral saltsMineral salts –From weathered rocks –Break down of Organic Matter (OM) –Addition of fertilizer
Page 14: Soil Chemistry. Mineral saltsMineral salts –From weathered rocks –Break down of Organic Matter (OM) –Addition of fertilizer

Plants which like acidic conditionsPlants which like acidic conditions

• Ericaceous plantsEricaceous plants (blueberry, cranberry, (blueberry, cranberry, azalea, rhododendron)azalea, rhododendron)

Page 15: Soil Chemistry. Mineral saltsMineral salts –From weathered rocks –Break down of Organic Matter (OM) –Addition of fertilizer

Plants which like acidic conditionsPlants which like acidic conditions

• Ericaceous plantsEricaceous plants (blueberry, cranberry, (blueberry, cranberry, azalea, rhododendron)azalea, rhododendron)

Page 16: Soil Chemistry. Mineral saltsMineral salts –From weathered rocks –Break down of Organic Matter (OM) –Addition of fertilizer

Plants which like acidic conditionsPlants which like acidic conditions

• Ericaceous plantsEricaceous plants (blueberry, cranberry, (blueberry, cranberry, azalea, rhododendron)azalea, rhododendron)

Page 17: Soil Chemistry. Mineral saltsMineral salts –From weathered rocks –Break down of Organic Matter (OM) –Addition of fertilizer

Plants which like acidic conditionsPlants which like acidic conditions

• Ericaceous plantsEricaceous plants (blueberry, cranberry, (blueberry, cranberry, azalea, rhododendron)azalea, rhododendron)

Page 18: Soil Chemistry. Mineral saltsMineral salts –From weathered rocks –Break down of Organic Matter (OM) –Addition of fertilizer

Plants which like acidic conditionsPlants which like acidic conditions

• Ericaceous plantsEricaceous plants (blueberry, cranberry, (blueberry, cranberry, azalea, rhododendron)azalea, rhododendron)

Page 19: Soil Chemistry. Mineral saltsMineral salts –From weathered rocks –Break down of Organic Matter (OM) –Addition of fertilizer

Soil ChemistrySoil Chemistry• If pH very low or very high, soil nutrients If pH very low or very high, soil nutrients

become unavailable to the plantbecome unavailable to the plant

• LimingLiming - raises the pH (makes the soil - raises the pH (makes the soil more basic) and is used on acidic soils.more basic) and is used on acidic soils.– CaCOCaCO33

– MgCOMgCO33

• Most of Vermont’s soils are Most of Vermont’s soils are acidicacidic• Most tropical soils are Most tropical soils are acidicacidic due to high due to high

rainfallrainfall

Page 20: Soil Chemistry. Mineral saltsMineral salts –From weathered rocks –Break down of Organic Matter (OM) –Addition of fertilizer

Liming DON’TSLiming DON’TS• You should You should NOTNOT lime your lawn after lime your lawn after

having applied a fertilizer that having applied a fertilizer that contains ammonium nitrate. The contains ammonium nitrate. The ammonium is converted to ammonium is converted to ammonia ammonia gasgas which can cause burning on the which can cause burning on the foliage of the grass and surrounding foliage of the grass and surrounding trees and shrubs!trees and shrubs!

Page 21: Soil Chemistry. Mineral saltsMineral salts –From weathered rocks –Break down of Organic Matter (OM) –Addition of fertilizer

Cliff of limestoneCliff of limestone

Page 22: Soil Chemistry. Mineral saltsMineral salts –From weathered rocks –Break down of Organic Matter (OM) –Addition of fertilizer
Page 23: Soil Chemistry. Mineral saltsMineral salts –From weathered rocks –Break down of Organic Matter (OM) –Addition of fertilizer

2H2H++ + 2OH + 2OH-- 2H 2H22O (water)O (water)

Page 24: Soil Chemistry. Mineral saltsMineral salts –From weathered rocks –Break down of Organic Matter (OM) –Addition of fertilizer

Soil ChemistrySoil Chemistry• Acidifying the soil or lowering the pHAcidifying the soil or lowering the pH

– Elemental sulfur (effect is temporary)Elemental sulfur (effect is temporary)

– Ammonium sulfate (effect is temporary)Ammonium sulfate (effect is temporary)– Aluminum sulfate is also used but not Aluminum sulfate is also used but not

recommended as aluminum is a heavy metal!recommended as aluminum is a heavy metal!

Page 25: Soil Chemistry. Mineral saltsMineral salts –From weathered rocks –Break down of Organic Matter (OM) –Addition of fertilizer

Soil ChemistrySoil Chemistry• Basic soils often can cause Basic soils often can cause iron chlorosisiron chlorosis in plants in plants

• This can be corrected by acidifying the soil This can be corrected by acidifying the soil or choosing a plant which is tolerant of or choosing a plant which is tolerant of alkaline soils!alkaline soils!

• Intervienal chlorosisIntervienal chlorosis: often on : often on acid-loving plants like roses, fruit trees,acid-loving plants like roses, fruit trees, azaleas and rhododendronsazaleas and rhododendrons

Page 26: Soil Chemistry. Mineral saltsMineral salts –From weathered rocks –Break down of Organic Matter (OM) –Addition of fertilizer
Page 27: Soil Chemistry. Mineral saltsMineral salts –From weathered rocks –Break down of Organic Matter (OM) –Addition of fertilizer
Page 28: Soil Chemistry. Mineral saltsMineral salts –From weathered rocks –Break down of Organic Matter (OM) –Addition of fertilizer
Page 29: Soil Chemistry. Mineral saltsMineral salts –From weathered rocks –Break down of Organic Matter (OM) –Addition of fertilizer

Blue in acidic soils <5.5Blue in acidic soils <5.5 with available aluminumwith available aluminum

Pink in neutral soils Pink in neutral soils near pH of 7near pH of 7

Page 30: Soil Chemistry. Mineral saltsMineral salts –From weathered rocks –Break down of Organic Matter (OM) –Addition of fertilizer