NRES 201 Lecture 29 Outline of Last Lecture I. Factors contributing to soil acidity II. Soil as a buffered systemIII. Determination of soil acidity IV. Estimating time requirementOutline of Current Lecture V. Fundamentals of limingVI. Neutralizing value of a liming materialVII. Liming CalculationsVIII. Common liming materialsIX. Soil acidificationX. Salt - affected soilsCurrent LectureFundamentals of liming- To supply a basic cation that will replace exchangeable H or Al- To inactivate the H+ released into the soil solutionNeutralizing Value of a liming materialCaCO3 equivalent (CCE)- The acid neutralizing capacity of a liming material expressed as a percent by weight ofpure CaCO3- By definition - the CCE is 100%Total fineness efficiency (TFE) - Finer particles are more reactiveEffective Neutralizing value (ENV) - A single index of limestone quality that accounts for both:Chemical composition (CCE) and particle size (TFE)- Defined as - ENV = CCE x TFE/100Common liming materialsLimestone- CaCO3 (calcite) - CCE is less than 90%- CaMg(CO3)2 (dolomite) - CCE is equal to 90 - 98%Calcium Oxide - produced by burning limestone. CCE = 179%Calcium Hydroxide - Produced by reacting CaO with water. CCE = 136%Marl - Unconsolidated CaCO3 derived from oyster shells. CCE = 70 - 90%These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.Slags - By product of steel mills. CCE = 60 - 90%Liquid Lime- Suspension of finely ground limestone in water- By - product of water treatment plants- Faster acting than dry limestone- But no residual benefitPelletized lime- Pellets formed from slaked limestone in water- Uniform particle size improves spreading - Far more expensive than crushed limestone- A major use is for turfgrassWhen is soil acidification needed?- Exposure of calcareous subsoil- Production of acidophilic cropso Potatoes, blueberries, cranberries, coniferous treesSoil acidulents- Elemental sulfuro Most efficient source of acidityo Acidification results from microbial activityo Requires a few weekso Slower in cold soils- Sulfuric acido Fast - actingo Rough on applicator equipment- Aluminum sulfateo Hydrolysis generates acidityo Fast acting but expensiveo Can lead to Al toxicity- Ferrous sulfateo Hydrolysis generates acidityo Supplies Fe as a micronutrientParameters to characterize salt affected soils- Soil pH- Exchangeable sodium percentage (ESP)o ESP = 100 x exch. Na/CEC- Electrical Conductivity (EC)o Standard lab method measures EC on saturated paste extracto Expressed as mmho/cmo Can be estimated by rapid field methods for georeferenced mapping of soilsalinity using: An electrode array Or electromagnetic inductionEffects of salinity on plant growth- Plants differ greatly in their tolerance of saline soils- Seedlings are more sensitive than mature plantsReclamation of salt affected soils- Saline soilso Leach soil with water to flush out salts but wait until the end of the growingseason so that NO3 and other nutrients are not flushed out tooo Calculate the leaching requirement (LR) to estimate the amount of water needed- Sodic and saline/ sodic soilso Reclamation difficulto Do not leach with watero Treat with gypsum to replace exchangeable
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