Field and laboratory procedures used in a soil chronosequence study

Abstract

FIGURES 1. Step-by-step procedures used to analyze soil samples 2 2. Profiles of Pleistocene terraces developed along the Cowlitz River upstream of Toledo, Washington 4 3. Example of a soil-description sheet used in the project 5 4. Correlation and regression analysis of field pH to lab pH 7 5. Percent <2m clay versus depth for horizon samples (solid line) and subsamples (dashed line) for two Merced samples 8 6. View of a sample in proper position over the cup horn 10 7. Construction of a Whittig-type wash bottle 13 8. Example of a temperature-time diagram used in particle-size analysis 14 9. Diagram of effects of dithionite pretreatment on particle-size distribution 15 10. Regression and correlation of saturation pH with 1:1 water pH 21 11. Regression and correlation of 1:1 KC1 pH with 1:1 water pH 21 12. Chittick apparatus and accessory equipment 31 13. Replicate analyses of CaCO3 content on calcareous soil samples and reagentgrade CaCO3 (100.01 percent) 33 14. Flow chart of dry-combustion train 34 III 15. Correlation and regression of Walkley-Black and dry-combustion carbon 36 16. Nitrogen distillation apparatus 37 17. Percent Fe extracted by citrate-bicarbonate-dithionite (CBD) for ground versus unground samples 41 TABLES 1. Comparison of cup horn ultrasonic soil dispersion with Calgon soil dispersion for soils from the Honcut Creek chronosequence 11 2. Sand and silt destruction during ultrasonic treatment 11 3. Settling times for 2-, 5-, and 20-m particles to pass through 10 cm of water 15 4. Repeat determinations of particle size for sample splitter vs. hand sampling 16 5. Effects of citrate-bicarbonate-dithionite pretreatment on particle-size distribution 16 6. Reproducibility of particle-size analysis by the pipette method 17 7. Example of reproducibility of bulk-density measurements of triplicate samples by the paraffin clod procedure 20 8. Reproducibility of soil pH measurements by three methods 21 9. Example of reproducibility and comparison of methods for cation exchange capacity (meq/100 g soil) 24 10. The effect of BaC12-triethanolamine in the measurement of CEC, extractable cations, and extractable acidity of various soils 24 11. Initial dilution recommendations for soil solution analyses by atomic absorption spectrophotometry 25 12. Initial concentration recommendations for atomic absorption spectrophotometry standard solutions 25 13. Preparation of standard solutions for atomic absorption spectrophotometry 25 14. Theoretical conductivity of 0.01 N KCl solution at varying temperatures 28 15. Factors for converting sample solution conductivity measured at varying temperatures to the standard 25 C 28 16. Example of reproducibility of total carbon analyses by dry combustion 35 17. Example of reproducibility of organic carbon analyses by the Walkley-Black procedure 36 18. CBD iron and aluminum extraction tests using two soil samples from the Santa Cruz chronosequence 39 19. Effect of organic matter removal upon the amount of iron determined 40 20. Example of magnetics removed from several soils by the proposed method 43 21. Step-by-step procedure for phosphorus fractionation 44