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Sweet and Sour Dirt. Sweet and Sour Dirt. A little understanding of pH to help you use biochar better. Contains animation. View in Slide Show mode. Contains animation. Soils Have Flavors!. It’s possible to taste a difference between different types of soil. Acidic soils taste sour
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SweetandSourDirt SweetandSourDirt A little understanding of pH to help you use biochar better Contains animation. View in Slide Show mode Contains animation
Soils Have Flavors! It’s possible to taste a difference between different types of soil • Acidic soils taste sour • Basic (alkaline) soils taste slightly sweet Mike Lieberman of UrbanOrganicGardener.com • The flavor of a soil affects… • How well different plants grow • What kind of microbes thrive in the soil • How well the solid holds on to various minerals • We talk about soil’s “flavor” as pH We don’t recommend this!
What Exactly is pH? …hydrogen ions (H+)… power of… pH • Water allows some hydrogen ions to escape from their molecules • pH tells the concentration of H+ in the solution • pH is a logarithmic (not linear) scale …in water compare with distilled water more acidic neutral more basic 6 0 1 2 3 4 5 7 8 9 10 11 12 13 14 1/10 10X 1/100 100X 1/1,000 1,000X 1/10,000 10,000X 1/100,000 100,000X etc. etc. Concentration of H+ vs. distilled water
Finding the pH (without tasting) Litmus paper colors shows pH Hydrangeas’ colors reflect soil pH Do-it-yourself home test kits Meters read pH directly
Strength of pH Acids • Acids release H+ • Basessuck up H+ • Acids and basesneutralizeeach other Acids Biochar Biochar is basic (alkaline). It can neutralize acidic soil. acidic
Soil’s Natural pH Varies Light rainfall & prairie neutral soils Heavy rainfall & forest acidic soils Cultivated & developed soils often differ from native soils Natural limestone bedrock alkaline soils Soil pH Drought & desert alkaline soils Strongly Acidic Mildly Acidic Neutral Mildly Alkaline But soils can also differ from one yard to another.
Different Plants Like Different Soils blueberry eucalyptus lilac azalea hydrangea geranium pomegranate ash white birch
Soil Ecology and pH Soil is a Living Community Supports Plants Supports Animals Unbalanced pH upsets the whole community
Soils and Mineral Availability Mineral availability in solution • Plants need many minerals to thrive • Plant roots only absorb minerals dissolved in water. • If solution is too acidic or alkaline, H+ chemistry locks up some nutrients. Nitrogen Phosphorus Potassium Sulfur Calcium Magnesium Iron Manganese Boron Copper and Zinc Examples: pH < 6.00 pH Source: Colorado State Extension CMG, GardenNotes #222 Near neutral pH is best for most minerals Mg deficiency Fe, Zn, Ma deficiency
Most Plants Like Near-Neutral Soils Best for minerals Best for fungi Best for bacteria Most plants grow in this range.
Neutralizing Because pH scale is not linear, neutralizing different strengths takes very different quantities Equal distances from neutral, use equal concentrations acid base acid base acid base = = = more acidic neutral more basic 6 0 1 2 3 4 5 7 8 9 10 11 12 13 14 One pH number further from neutral, use 1/10th as much of the stronger Two pH numbers further from neutral, use 1/100th as much of the stronger
How to Modify Soil pH First – Test Your Soil !!!!! Adding organic matter to the soil makes both acid and alkaline soils more neutral. Add one of the following: Ground limestone lasts a long time Hydrated Lime works quickly easy to over-do Wood Ashes fast-acting a little goes a long way Add one of following: Granular sulfur slow acting Aluminum & Iron Sulfate faster need a lot Acidifying fertilizer Doesn’t work well for pH > 7.5 May contain a large amount of calcium carbonate Lower Soil pH (improve alkaline soil) Raise Soil pH (improve acid soils) ***** ALWAYS FOLLOW DIRECTIONS ****
Biochar and pH • Biochar is usually alkaline • Biochar pH depends on the pyrolysis temperature typical pH range typical formation temperature range neutralizes Biochar’s neutralizing power diminishes after a few years. Note: ash created by pyrolysis is strongly alkaline (pH 12-13) biochar acidic soil
Using Biochar to Change Soil pH First – Test Your Soil !!!!! • If your soil is already alkaline, don’t use biochar! • Because biochar is a pretty strong base, use it sparingly 2% by volume per application • To keep pH moderate, add small amounts • of biochar every few years, not all at once. • If your soil is strongly acidic(<ph 5), • you can mix a small amount of ashinto the biochar. • Ash adds important minerals (calcium, sulfur, potassium, phosphorus, magnesium) strongly acidic