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and Sour Dirt Sweet and Sour Dirt A little understanding of pH to help you use biochar better Sweet Sour Dirt Sweet and Sour Dirt Contains animation Contains animation. View in Slide Show mode
Soils Have Flavors! ~2~ Acidic soils taste sour Basic (alkaline) soils taste slightly sweet Mike Lieberman of UrbanOrganicGardener.comUrbanOrganicGardener.com We don’t recommend this! It’s possible to taste a difference between different types of soil It’s possible to taste a difference between different types of soil 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
What Exactly is 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 ~3~ pH power of… …hydrogen ions (H + )… Concentration of H + vs. distilled water 012345 6 7891011121314 neutral more acidic more basic 10X 100X 1,000X 10,000X 100,000X 1 / 10 1 / 100 1 / 1,000 1 / 10,000 1 / 100,000 etc. …in water compare with distilled water
Finding the pH (without tasting) 4 Hydrangeas’ colors reflect soil pHLitmus paper colors shows pH Meters read pH directly Do-it-yourself home test kits
Strength of pH Acids Acids release H + Bases Bases suck up H + Acidsbases neutralize Acids and bases neutralize each other ~5~ Biochar is basic (alkaline). It can neutralize acidic soil. Acids acidic
Soil’s Natural pH Varies 6 Soil pH Strongly Acidic Mildly Acidic Mildly Alkaline Neutral Heavy rainfall & forest acidic soils Light rainfall & prairie neutral soils Drought & desert alkaline soils alkaline soils Natural limestone bedrock alkaline soils Cultivated & developed soils often differ from native soils But soils can also differ from one yard to another.
Different Plants Like Different Soils ~7~ lilac ash blueberry white birch eucalyptus pomegranate geranium azalea hydrangea
Soil is a Living Community Soil Ecology and pH ~8~ ResidentWhat it doesEffect of pHFungi Decompose dead plants, animals, and bacteria into nutritious molecules Some live in plant roots to help plants take up nutrients Prefer slightly acidic pH Bacteria Decompose dead plants, animals, and fungi into living molecules Exude nutritious molecules Become food for higher organisms Prefer slightly alkaline pH Insects & worms Excrete plant fertilizer Open spaces in soil to let in air and water to support soil life Become food for bacteria and fungi Don’t like extreme pH Worms avoid acid pH Supports Plants Supports Animals Unbalanced pH upsets the whole community
Source: Colorado State Extension CMG, GardenNotes #222 pH Mineral availability in solution Soils and Mineral Availability 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. ~9~ Examples: pH < 6.00 Mg deficiency Fe, Zn, Ma deficiency Near neutral pH is best for most minerals Nitrogen Phosphorus Potassium Sulfur Calcium Magnesium Iron Manganese Boron Copper and Zinc Nitrogen Phosphorus Potassium Sulfur Calcium Magnesium Iron Manganese Boron Copper and Zinc
Most Plants Like Near-Neutral Soils ~10~ Best for minerals Best for fungi Best for bacteria Most plants grow in this range.
Neutralizing ~11~ Because pH scale is not linear, neutralizing different strengths takes very different quantities Equal distances from neutral, use equal concentrations One pH number further from neutral, use 1/10 th as much of the stronger Two pH numbers further from neutral, use 1/100 th as much of the stronger 012345 6 7891011121314 neutral more acidic more basic acidbase = acidbase = acid base =
How to Modify Soil pH ~12~ 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 Raise Soil pH (improve acid soils) 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) ***** ALWAYS FOLLOW DIRECTIONS **** First – Test Your Soil !!!!! First – Test Your Soil !!!!!
Biochar and pH alkaline Biochar is usually alkaline Biochar pH depends on the pyrolysis temperature ~13~ typical formation temperature range typical pH range biochar acidic soil neutralizes N OTE : ash created by pyrolysis strongly alkaline is strongly alkaline (pH 12-13) Biochar’s neutralizing power diminishes after a few years.
Using Biochar to Change Soil pH alkaline If your soil is already alkaline, don’t use biochar! strong basesparingly Because biochar is a pretty strong base, use it sparingly ~14~ First – Test Your Soil !!!!! First – Test Your Soil !!!!! To keep pH moderate, add small amounts of biochar every few years, not all at once. strongly acidic If your soil is strongly acidic (<ph 5), ash you can mix a small amount of ash into the biochar. – Ash adds important minerals (calcium, sulfur, potassium, phosphorus, magnesium) 2% by volume per application strongly acidic