NRES 201 Lecture 29 Outline of Last Lecture I Factors contributing to soil acidity II Soil as a buffered system III Determination of soil acidity IV Estimating time requirement Outline of Current Lecture V Fundamentals of liming VI Neutralizing value of a liming material VII Liming Calculations VIII Common liming materials IX Soil acidification X Salt affected soils Current Lecture Fundamentals of liming To supply a basic cation that will replace exchangeable H or Al To inactivate the H released into the soil solution Neutralizing Value of a liming material CaCO3 equivalent CCE The acid neutralizing capacity of a liming material expressed as a percent by weight of pure CaCO3 By definition the CCE is 100 Total fineness efficiency TFE Finer particles are more reactive Effective 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 100 Common liming materials Limestone 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 benefit Pelletized lime Pellets formed from slaked limestone in water Uniform particle size improves spreading Far more expensive than crushed limestone A major use is for turfgrass When is soil acidification needed Exposure of calcareous subsoil Production of acidophilic crops o Potatoes blueberries cranberries coniferous trees Soil acidulents Elemental sulfur o Most efficient source of acidity o Acidification results from microbial activity o Requires a few weeks o Slower in cold soils Sulfuric acid o Fast acting o Rough on applicator equipment Aluminum sulfate o Hydrolysis generates acidity o Fast acting but expensive o Can lead to Al toxicity Ferrous sulfate o Hydrolysis generates acidity o Supplies Fe as a micronutrient Parameters 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 extract o Expressed as mmho cm o Can be estimated by rapid field methods for georeferenced mapping of soil salinity using An electrode array Or electromagnetic induction Effects of salinity on plant growth Plants differ greatly in their tolerance of saline soils Seedlings are more sensitive than mature plants Reclamation of salt affected soils Saline soils o Leach soil with water to flush out salts but wait until the end of the growing season so that NO3 and other nutrients are not flushed out too o Calculate the leaching requirement LR to estimate the amount of water needed Sodic and saline sodic soils o Reclamation difficult o Do not leach with water o Treat with gypsum to replace exchangeable Na
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