1 .Soils of Arid And Semi-Arid Regions

1.1  Calcareous Soils                                                                                                   

1.2  Gypsiferous Soils                                                                                                  

1.3  Salt Affected Soils

2 .Soil Sampling and Preparation

2.1  Soil Sampling Tools

2.2  Sampling for Soil Fertility Tests                                                                            

2.2.1  Time of Sampling                                                                                           

2.2.2  Depth of Sampling

2.2.3  Methods of Sampling

2.3  Soil Sampling for Soil Survey and Classification Studies

2.4  Preparation of Soil Samples                                                                                 

2.5  Grinding and Sieving of Soil Samples

2.6  Reduction of Sample Size

3 .Soil Moisture                                                                                                       

4 .Soil Texture – Particle Size Distribution

4.1  Introduction                                                                                                           

4.2  Dispersion

4.3  Sedimentation

4.4  Bouyoucos Method

4.5  Gypsum Removal from Soil                                                                                  

4.5.1  Gypsum Removal by Ammonium Oxalate

4.5.2  Gypsum Removal by Hydrochloric Acid                                                        

4.5.3  Pretreatment of Soil with BaCl2 to Coat Gypsum with BaSO4                       

4.5.4  Pretreatment of Soil with BaCl2 Solution followed by Ethanol

4.5.5  Pretreatment with BaCl2 Solution (Modified Method)                                     

5 .Soil Density and Total Pore Space                                                             

5.1  Introduction

5.2  Measurement of Bulk Density                                                                               

5.2.1  Bulk Density of a Disturbed Soil Sample

5.2.2  Bulk Density of an Undisturbed Soil Sample                                                 

5.3  Measurement of Particle Density

5.3.1  The Graduated Cylinder Method

5.3.2  The Volumetric Flask Method                                                                        

5.4  Calculation of Percent Pore Space

6 .Analysis of Saturation Paste Extract

6.1  Introduction

6.2  Preparation of Saturation Paste                                                                            

6.2.1  Calculation of Saturation Percentage                                                            

6.2.2  Determination of Soil pH                                                                               

6.3  Preparation of Saturation Extract

6.3.1  Determination of Soil Salinity (Electric Conductivity)                                     

6.3.2  Determination of Soluble Sodium and Potassium

6.3.3  Determination of Soluble Calcium and Magnesium

6.3.4  Determination of Carbonate and Bicarbonate                                               

6.3.5  Determination of Chloride                                                                              

7 .Calcium Carbonate                                                                                           

7.1  Determination of Total Calcium Carbonate                                                           

7.2  Determination of Active Calcium Carbonate

8. Cation Exchange Capacity (CEC)                                                                   

8.1  Determination of Cation Exchange Capacity (CEC)                                             

8.2  Determination of CEC in Gypsiferous and Calcareous Soils                                

8.3  Exchangeable Sodium Percentage                                                                      

9. Soil Gypsum                                                                                                           

10. Soil Organic Matter                                                                                          

10.1  Walkley – Black Wet Combustion Method                                                            

11. Soil Nitrogen                                                                                                       

11.1  Total Nitrogen (Kjeldahl method)                                                                          

11.2  Determination of Mineral Nitrogen                                                                        

11.2.1  Determination of Nitrate by the Phenoldisulfonic Acid Method

11.2.2  Determination of Nitrate by the Specific Ion Electrode                                  

11.3  Extraction of Exchangeable Ammonium                                                               

11.3.1  Determination of Ammonium by Indophenol Blue Method                             

11.3.2  Determination of Ammonium by Specific Ion Electrode

12. Soil Phosphorous                                                                                              

12.1  Fractionation of Soil Phosphorous                                                                        

12.2  Fate of Applied Phosphatic Fertilizer                                                                    

12.3  Influence of Soil Parent Materials on the Distribution of the Inorganic Pfractions

12.4  Phosphorous Retention                                                                                        

12.5  Iron and Aluminium Amorphous Phosphate in Calcareous Soils                         

12.6  Determination of Available Phosphorous (Olsen’s method)                                 

13. Soil Potassium                                                                                                   

13.1  Determination of Available Potassium                                                                  

13.2  Determination of Fixed Potassium                                                                       

14. Soil Sulphur                                                                                                        

15. Gypsum Requirement                                                                                         

16. Soil Micronutrients                                                                                          

16.1  Iron, Zinc, Manganese and Copper                                                                      

16.1.1  Iron                                                                                                              

16.1.2  Zinc                                                                                                               

16.1.3  Manganese                                                                                                   

16.1.4  Copper                                                                                                           

16.2  Determination of Available Micronutrients                                                            

16.2.1  DTPA Extraction Method                                                                               

16.2.2  Measurement of Element Concentration Using Atomic Absorption Spectroscopy                                                                                                 

16.3  DTPA Extractability and Availability for Plant Uptake                                           

17. Soil Boron                                                                                                             

17.1  Total Boron by Na2CO3 Fusion                                                                             

17.2  Available Boron by Hot Water Extraction                                                             

17.3  Measurement of Concentration by Colourimetric Methods                                  

17.3.1  Colour Development – Carmine Method                                                     

17.3.2  Colour Development – Azomethine-H Method                                              

18. Soil Molybdenum                                                                                                

19. Soil Selenium                                                                                                        

20. Potentially Toxic Elements - CD, CR, NI AND PB                                       

21. Identification Of Clay Minerals By X-Ray Diffraction (XRD)           

References                                                                                                                    

List of Tables

Table 1. Chemical characteristics of saline, non-saline sodic and saline-sodic soils          

Table 2. Electrical conductivity values for different CaSO4 concentrations in water            

Table 3. Effect of pretreatments on the d-spacing of selected clay minerals                    

List of Figures

Figure 1. Sampling pattern for fertility test in a non-uniform land                                        

Figure 2. Sampling-sites selection methods for fertility test                                                

Figure 3. Field datasheet                                                                                                 

Figure 4. Reduction of sample size by quartering                                                              

Figure 5.Datasheet for the recording of hydrometer readings                                                

Figure 6. Texture triangle showing the percentages of sand, silt and clay in the textural classes                                                                                                    

Figure 7. Modified textural triangle for determining soil texture by the feel method            

Figure 8. Effect of soil: water ratio and particle size on total gypsum extraction                  

Figure 9. Identification of kaolinite using its characteristic XRD patterns                         

Figure 10. Identification of smectite using its characteristic XRD patterns                      

List of Appendices

Appendix A.  List of the atomic weights of the elements                                                    

Appendix B.  pH indicators                                                                                                

Appendix C.  Properties of laboratory materials                                                                

Appendix D.  Grades of chemicals                                                                                    

Appendix E . Nutrient range in soils, mg/kg (Bashour, 2001)                                             

Appendix F. Temperature factors (ft) for correcting resistance and conductivity data on soil extracts to the standard temperature of 25°C                                         

Appendix G.  Conversion factors for SI and non-SI units (Soil Science Society of America Journal)