Soil Survey Field and Laboratory Methods Manual
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SOIL SURVEY FIELD AND LABORATORY METHODS MANUAL Soil Survey Investigations Report No. 51 Version 1.0 Compiled and Edited by Rebecca Burt National Soil Survey Center Natural Resources Conservation Service U.S. Department of Agriculture Lincoln, Nebraska SOIL SURVEY FIELD AND LABORATORY METHODS MANUAL Soil Survey Investigations Report No. 51 Version 1.0 Compiled and Edited by Rebecca Burt National Soil Survey Center Natural Resources Conservation Service U.S. Department of Agriculture Lincoln, Nebraska Issued 2009 Trade names are used in this manual solely for the purpose of providing specific information. Mention of a trade name does not constitute a guarantee of the product by USDA nor does it imply an endorsement by USDA. 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Citation: Soil Survey Staff. 2009. Soil Survey Field and Laboratory Methods Manual. Soil Survey Investigations Report No. 51, Version 1.0. R. Burt (ed.). U.S. Department of Agriculture, Natural Resources Conservation Service. ii CONTENTS Page Preface xiii Contributors xvii Acknowledgements xix User’s Guide xxi 1. FIELD ASSESSMENT AND SAMPLING STRATEGIES 1 1.1 Soil Survey 1 1.1.1 Field Sample Collection and Preparation 1 1.1.1.1 Site Selection 1 1.1.1.2 Geomorphology 1 1.1.1.3 Pedon 1 1.1.1.4 Water 1 1.1.1.5 Biological 1 1.2 Other Sampling Strategies 15 1.2.1 Composite Random Sampling 15 1.2.2 Diagonal and Zigzag Sampling 15 1.2.3 Benchmark Sampling 15 1.2.4 Landscape Directed Sampling 15 1.2.5 Grid Sampling 15 1.3 Field Assessment 17 1.3.1 Salinity, Sodicity, and pH 17 1.3.1.1 Saline Soils 17 1.3.1.2 Sodic Soils 17 1.3.1.3 High pH Soils 17 1.3.1.4 Interactions, Salinity, Sodicity, and High pH 17 1.3.1.5 Sampling for Salinity, Sodicity, and High pH 17 1.3.2 Soil Fertility and Plant Nutrition 19 1.3.2.1 Soil Sampling as Basis for Fertilizer Applications 19 1.3.2.2 Plant Analysis as Basis for Fertilizer Applications 19 1.3.2.3 Remote Sensing for Crop Nitrogen Status and Plant Biomass 19 1.4 Laboratory Sample Collection and Preparation 21 1.4.1 Soils 21 1.4.1.1 Field-Moist Preparation 21 1.4.1.1.1 Particles <2 mm 21 1.4.1.2 Air-Dry Preparation 21 1.4.1.2.1 Particles <2 mm 21 1.4.1.2.2 Particles >2 mm 21 1.4.1.2.2.1 Particle-Size Analysis 21 2. CONVENTIONS 24 2.1 Data Types 24 2.2 Size-Fraction Base for Reporting Data 24 2.2.1 Particles <2 mm 24 iii 2.2.2 Particles <Specified Size> 2 mm 24 2.3 Soil Sample Weight Base for Reporting Data 24 2.3.1 Air-Dry/Oven-Dry Ratio 24 2.3.2 Field-Moist/Oven-Dry Ratio 24 2.3.3 Correction for Crystal Water 24 2.4 Significant Figures and Rounding 25 2.5 Data Sheet Symbols 25 3. SOIL PHYSICAL ANALYSES 25 3.1 Soil Morphology 25 3.1.1 Color 26 3.1.1.1 Color Charts 26 3.1.1.2 Ignition 28 3.1.1.3 Alkaline Solution 29 3.1.1.4 Dispersion 29 3.1.1.5 Hydrogen Peroxide 29 3.1.2 Structure and Consistence 20 3.1.2.1 Soil Morphology Index 29 3.1.2.2 Singleton Blade and Modified Singleton Blade 32 3.1.2.3 Near-Surface Subzones 34 3.1.2.4 Horizon Examination 35 3.1.2.4.1 Ped Faces 35 3.1.2.4.2 Pores and Other Voids 37 3.1.2.4.3 Packing 38 3.1.2.4.4 Other Structural Features 38 3.1.3 Podzol and Podzolic Soil Development 38 3.1.3.1 Numberical (Color) Index of Podzol and Podzolic Development (POD) 38 3.2 Particle-Size Distribution Analysis 40 3.2.1 Particles <2mm 40 3.2.1.1 Field Analysis of Particles <2 mm 41 3.2.1.1.1 Feel Method 41 3.2.1.2 Laboratory Analysis of Particles <2 mm 46 3.2.1.2.1 Hydrometer Analysis for Routinely Reported Size Fractions (1, 0.5, 0.25, 0.1, 0.047 mm, 0.002–0.05 mm, and <2 m) 46 3.2.1.2.1.1 Sodium Hexametaphosphate Dispersible 46 3.2.1.2.1.1.1 Organic Matter Removal 46 3.2.1.2.1.1.1.1 Hydrogen Peroxide 46 3.2.1.2.1.1.1.2 Sodium Hypochlorite 46 3.2.1.2.1.1.2 Carbonate Removal 46 3.2.1.2.1.1.3 Iron Removal 46 3.2.1.2.1.1–3.1 Air-Dry 46 3.2.1.2.2 Micro-pipette Method for Routinely Reported Size Fractions (1, 0.5, 0.25, 0.1, 0.047 mm, 0.002–0.05 mm, and <2 m) 53 3.2.1.2.2.1 Water Dispersible 53 3.2.1.2.2.1.1 Air-Dry 53 3.2.2 Particles >2 mm 57 3.2.2.1 Field Analysis of Particles >2 mm 57 3.2.2.2 Field and Laboratory Analysis of Particles >2 mm 59 iv 3.2.2.2.1 Weight Estimates 59 3.2.2.2.1.1 By Field and Laboratory Weighing 59 3.2.2.2.1.2 From Volume and Weight Estimates 62 3.2.2.2.2 Volume Estimates 62 3.3 Bulk Density 66 3.3.1 Field State 66 3.3.1.1 Compliant Cavity 67 3.3.1.2 Ring Excavation 70 3.3.1.3 Frame Excavation 72 3.3.1.4 Soil Cores 74 3.4 Water Retention 77 3.4.1 Desorption on Hectorite 77 3.4.1.1 1500-kPa Water Retention 77 3.4.1.1.1 <2-mm (sieved), Air-Dry Sample 77 3.4.2 Field-State 81 3.4.3 Plant Available and Unavailable Water Estimates, Volume Basis 82 3.4.4 Water State Classes 84 3.5 Ratios and Estimates Related to Particle-Size Analysis, Bulk Density, and Water Retention 85 3.5.1 Air-Dry/Oven-Dry Ratio 85 3.5.2 Field-Moist/Oven-Dry Ratio 85 3.5.3 Correction for Crystal Water 85 3.5.4 Coefficient of Linear Extensibility (COLE) 89 3.5.4.1 Soil Clod or Core 89 3.5.4.2 Soil Pastes 91 3.5.4.3 Soil Molds 92 3.5.5 1500-kPA Water Content/Total Clay 93 3.6 Water Flow 94 3.6.1 Single-Ring Infiltrometer 94 3.6.2 Double-Ring Infiltrometer 96 3.6.3 Amoozemeter, Compact Constant Head Permeameter 99 3.7 Soil Stability, Dispersion, and Slaking 106 3.7.1 Aggregate Stability 106 3.7.1.1 Wet Sieving, Air-Dry, 2 to 1 mm, 2- to 0.5-mm Aggregates Retained 106 3.7.1.2 Wet Sieving, Air-Dry, <2 mm, >0.25 mm Aggregates Retained 108 3.7.2 Slaking as Measure of Soil Stability when Exposed to Rapid Wetting 110 3.7.3 Dispersion as an Indicator of Soil Sodicity and Permeability (Crumb Test) 112 3.7.4 Dispersion, Electrical Conductivity (EC), and pH as Indicators of Soil Salinity, Acidity, and Sodicity 114 3.7.5 Slaking (Disaggregation) for Identification and Semiquantification of Cemented Materials 116 3.8 Soil Water Repellency 127 3.8.1 Water Drop Penetration Test (WDPT) 127 3.8.2 Mini-disk Infiltrometer 129 v 3.9 Engineering Tests 133 3.9.1 Atterberg Limits 133 3.9.1.1 Liquid Limit (LL) 133 3.9.1.1.1.1 Air-Dry, <0.4 mm 133 3.9.1.1.2.1 Field-Moist, <0.4 mm 133 3.9.1.2 Plasticity Index 133 3.9.1.2.1.1 Air-Dry, <0.4 mm 133 3.9.1.2.2.1 Field-Moist, <0.4 mm 133 3.9.2 United Soil Classification System Using Field Procedures 133 3.9.2.1 Grain Size and Gradation 134 3.9.2.2 Liquid Limit Evaluation 134 3.9.2.3 Dilatency Test 135 3.9.2.4 Toughness Test and Plasticity Evaluation 136 3.9.2.5 Ribbon Test 136 3.9.2.6 Shine Test 137 3.9.2.7 Dry Strength Test 137 3.9.2.8 Odor Test 138 3.9.2.9 Evaluation of Clean and Dirty Sands and Gravel 138 3.9.2.10 Field Description of Fine-Grained Soils 139 3.9.2.11 Field Description of Coarse-Grained Soils 140 3.9.2.12 Borderline Classifications 141 4.