pH and Liming Practices pH and Liming Practices Kent Martin Kent - PowerPoint PPT Presentation

pH and Liming Practices pH and Liming Practices Kent Martin Kent Martin Stafford County Stafford County 1/5/2010 1/5/2010

Outline Outline What is pH What is pH Normal pH ranges Normal pH ranges Acid Soil Acid Soil Importance of soil pH Importance of soil pH Factors affecting soil pH Factors affecting soil pH Acid types and measurement Acid types and measurement Neutralizing value of materials Neutralizing value of materials Soil sampling and pH analysis Soil sampling and pH analysis Summary Summary

What is pH What is pH A measure of the relative acidity of a substance A measure of the relative acidity of a substance Negative logarithm of the hydrogen ion Negative logarithm of the hydrogen ion concentraion concentraion pH H + Concentration or 10 -5 5.0 0.00001 6.0 0.000001 or 10 -6 0.0000001 or 10 -7 7.0 0.00000001or 10 -8 8.0

What is pH What is pH pH is a convenient notation pH is a convenient notation -5 5 ) (5.0 is easier to use than 0.00001 or 10 - ) (5.0 is easier to use than 0.00001 or 10 The H in pH stands for hydrogen ions The H in pH stands for hydrogen ions A change in pH of one unit equals a 10 fold A change in pH of one unit equals a 10 fold + concentration change in H + concentration change in H A change of pH 6.0 to 5.7 doubles the acidity A change of pH 6.0 to 5.7 doubles the acidity pH Range < 7.0 Acid >7.0 Alkaline 7 14 0

Normal pH Range Normal pH Range pH Scale 14 Lye Solution 13 Washing Soda 12 Alkaline 11 10 Milk of Magnesia 9 Hard Water 8 Neutral 7 Normal pH Range Milk 6 5 4 Coffee Acid Coca Cola 3 Stomach Acid 2 Battery Acid 1 Sulfuric Acid 0

Normal pH Range Normal pH Range Neutrality Acidity Alkalinity Very Very Strong Moderate Slight S light Moderate Strong Strong Strong 3 4 5 6 7 8 9 10 11 Humid region mineral soils Acid Alkali peat soils mineral Arid Region Mineral Soils Extreme range in pH for most soils mineral soils

What is Acid Soil What is Acid Soil Ca +2 K +1 Mg +2 Soils have a net negative charge - - - - - - H +1 Positively charged ions, cations, - Ca +2 are retained, preventing their - Soil Mg +2 leaching. - Na +1 - The balance of acidic and basic NH 4 +1 ions determines soil pH - - - - - - Ca +2 Al +3

Importance of Soil pH Importance of Soil pH Low pH: Dissolves Al +++ +++ Low pH: Dissolves Al 1000 times more soluble at 4.5 pH than 5.5 pH 1000 times more soluble at 4.5 pH than 5.5 pH Causes plant toxicity Causes plant toxicity Interferes with microbe activity, which affects: Interferes with microbe activity, which affects: Nutrient cycling Nutrient cycling Legume nodulation Legume nodulation Residue decomposition Residue decomposition Diseases Diseases Herbicide breakdown and carryover Herbicide breakdown and carryover High pH: Low nutrient availability High pH: Low nutrient availability P, Zn, Fe P, Zn, Fe

Importance of Soil pH Importance of Soil pH Low soil pH and Al toxicity pH 5.2 pH 4.5 Reno County, KS 2008

Importance of Soil pH Importance of Soil pH Wheat response to lime Lime pH Yield (bu bu/a) /a) Al (ppm ppm) ) Lime pH Yield ( Al ( (ECC/a) (ECC/a) 0 4.6 14 102 0 4.6 14 102 3000 5.1 37 26 3000 5.1 37 26 6000 5.9 38 0 6000 5.9 38 0 12000 6.4 37 0 12000 6.4 37 0 Kansas State University

Importance of Soil pH Importance of Soil pH Active Al Increased by Soil Acidity 50 45 -9.6 y = 3E+07x 40 2 = 0.86 % Al saturation R 35 30 25 20 15 10 5 0 3.8 4 4.2 4.4 4.6 4.8 5 5.2 5.4 5.6 pH Oklahoma State University

Importance of Soil pH Importance of Soil pH Colorado State University Extension

Factors Affecting Soil pH Factors Affecting Soil pH Parent Material Parent Material Annual Precipitation Annual Precipitation � Higher rainfall � Lower pH Higher rainfall Lower pH Native Vegetation Native Vegetation Crop Grown Crop Grown Legumes remove more Ca and Mg than nonlegumes nonlegumes Legumes remove more Ca and Mg than Microbial Nitrification Microbial Nitrification 1- -2 lbs of lime to neutralize 1 lb N 2 lbs of lime to neutralize 1 lb N 1

Factors Affecting Soil pH Factors Affecting Soil pH The process of nitrification creates soil acidity The process of nitrification creates soil acidity + released Ammonium conversion to nitrate = H + released Ammonium conversion to nitrate = H NH 4+ + 2O 2 NO 3- + 2H + + H 2 O Nitrifying Bacteria Ammonium Oxygen Nitrate Hydrogen Water Lime required to neutralize acidity from N Lime required to neutralize acidity from N application application N Source Lb ECC/lb N N Source Lb ECC/lb N Ammonia, Urea, UAN 1.8 Ammonia, Urea, UAN 1.8 Ammonium Sulfate 5.4 Ammonium Sulfate 5.4 DAP DAP 3.6 3.6 MAP MAP 7.2 7.2

Factors Affecting Soil pH Factors Affecting Soil pH N Rate Continuous Corn Sorn/Soybean /Soybean N Rate Continuous Corn Sorn ---------------Soil pH Soil pH--------------- --------------- --------------- 0 6.5 6.5 0 6.5 6.5 50 6.0 6.4 50 6.0 6.4 100 5.5 6.3 100 5.5 6.3 200 4.8 5.8 200 4.8 5.8 North Central Kansas Experiment Field, Dr. Barney Gordon

Acid Types and Measurement Acid Types and Measurement Active Acidity Active Acidity Affects soil chemical reactions and plant growth Affects soil chemical reactions and plant growth Measured as soil or water pH Measured as soil or water pH Neutralized by <1 pound calcium carbonate/acre Neutralized by <1 pound calcium carbonate/acre Reserve Acidity Reserve Acidity The total acidity The total acidity Affects the quantity of lime required Affects the quantity of lime required Measured by buffer pH (buffer index) Measured by buffer pH (buffer index)

Acid Types and Measurement Acid Types and Measurement Reserve Acidity Active Acidity H + H + H + H + H + H + H + H + H + H + H + Soil Solution H + Ions H + H + (Active Acidity) H + Section of Soil H + H + Colloid H + H + H + H + H + H + H + H + H + H + H + H + H +

Acid Types and Measurement Acid Types and Measurement Soil pH is a measure of the acidity of the soil solution Soil pH is a measure of the acidity of the soil solution Buffer pH is a measure of the potential acidity due to the soil Buffer pH is a measure of the potential acidity due to the soil solution and the exchange sites solution and the exchange sites Soil 1 Soil 2 H + H + K + Mg ++ Ca ++ H + H + Ca ++ K + Mg ++ H + + Mg ++ NH 4 + NH 4 Ca ++ (Soil Water) (Soil Air) (Soil Water) (Soil Air) H + H + Mg ++ Ca ++ K + H + K + Ca ++ H + K + Mg ++ Ca ++ NH 4 + H + H + Exchange sites of Clay particles Same soil pH values, but different buffer pH; soil 2 will Same soil pH values, but different buffer pH; soil 2 will require more lime than soil 1. require more lime than soil 1.

Acid Types and Measurement Acid Types and Measurement Could we use this as an example of sandy loam Could we use this as an example of sandy loam vs. clay loam vs. clay loam Soil 1 Soil 2 H + H + K + Mg ++ Ca ++ H + H + Ca ++ K + Mg ++ H + NH 4 + Mg ++ + NH 4 Ca ++ (Soil Water) (Soil Air) (Soil Water) (Soil Air) H + H + Mg ++ Ca ++ K + H + K + Ca ++ H + K + Mg ++ Ca ++ NH 4 + H + H + Exchange sites of Clay particles

How Does Lime Work? How Does Lime Work? Calcium Carbonate H + Ca + H 2 O + CO 2 H + + CaCO 3 Gypsum H + Ca + 2H + + SO 4 + CaSO 4 H +

Neutralizing Value of Materials Neutralizing Value of Materials Liming Material Composition Relative Neutralizing Value Calcium Carbonate CaCO 3 100 Calcitic Lime CaCO 3 + Impurities 50-100 Dolomitic Lime CaCO 3 + MgCO 3 +Impurities 90-109 Quicklime (burned lime) CaO 150-180 Hydrated lime (slaked lime) Ca(OH) 2 115-135 Ground shells 80-90 Wood ashes 40-80

Neutralizing Value of Materials Neutralizing Value of Materials Determined by: Determined by: Purity – – calcium carbonate equivalent calcium carbonate equivalent Purity % liming agent vs. % inert materials % liming agent vs. % inert materials Fineness – – particle size particle size Fineness Determined by dry sieves (8 and 60 mesh) Determined by dry sieves (8 and 60 mesh) Fine particles dissolve more quickly than coarse Fine particles dissolve more quickly than coarse Expressed as Effective Calcium Carbonate Expressed as Effective Calcium Carbonate Equivalent (ECCE) Equivalent (ECCE)

Neutralizing Value of Materials Neutralizing Value of Materials Size Fraction Dissolved After 1 Size Fraction Dissolved After 1 Year (%) Year (%) < 60 mesh 100 < 60 mesh 100 60- -8 mesh 8 mesh 50 60 50 >8 mesh 0 >8 mesh 0

Neutralizing Value of Materials Neutralizing Value of Materials Example: Example: Size Fraction Material (%) Effectiveness Effectiveness Size Fraction Material (%) Effectiveness Effectiveness Factor Factor >8 0 0.0 0 >8 0 0.0 0 8- -60 60 60 0.5 30 8 60 0.5 30 <60 40 1.0 40 <60 40 1.0 40 Fineness = 70 If a quarry has 80% CCE, the ECC is 70 × × 0.86 = 60.2 0.86 = 60.2 If a quarry has 80% CCE, the ECC is 70 (Combination of purity and fineness) (Combination of purity and fineness)