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PART VI. ALKALINITY OF SOILS . . . . . . . . . . . . . . 172 



Effect of rain on soil texture and composition . . . . . . . . 172 



Irrigation and soil salinity . . . . . . . . . . . . . . 172 



Method of taking samples for alkalinity tests . . . . . . . . 173 



Distribution of salts in soil mass . . . . . . . . . . . . 173 



Hilgard's and Leather's experiments .. .. .. .. .. .. 173 



Methods of analysis . . . . . . . . . . . . . . . . 174 



Analytical results : 175 



Division of Herbert : Douglas . . . . . . . . . . . . 176 



Colesberg : Oorlogspoort .. .. .. .. .. 177 



Britstown : Houwwater .. .. .. .. .. 177 



Steynsburg : Thebus .. .. .. .. 180 



Robertson : Experiment Station . . . . . . . ; 184 



Carnarvon : Van Wyk's Vlei 185 



PART VII. PHYSICAL COMPOSITION OF SOILS . . . . . . . . . . 188 



Fertility and productiveness . . . . . . . . . . . . . . 188 



Connection of chemical composition and texture in soils . . . . . . 188 



Varieties of soil classification . . . . . . . . . . . . . . 189 



The grading of soil particles . . . . . . . . . . . . . . 190 



Importance of silt and clay . . . . . . . . . . . . . . 191 



Methods of mechanical analysis . . . . . . . . . . . . 193 



Analytical results . . . . . . . . . . . . . . . . . . 195 



Geological relationship and soil texture . . . . . . . . . . 195 



Mechanical analyses of various soils . . . . . . . . . . . . 197 



Stellenbosch Division : Elsenberg . . . . . . . . . . . . 198 



Paarl Division 198 



Steynsburg Division : Thebus 199 



Robertson Division : Experiment Station . . . . . . . . . . 199 



Prieska Division : Buchuberg. . . . . . . . . . . . . 201 



Cape Division : Koeberg . . . . . . . . . . . . . . 203 



CONCLUDING OBSERVATIONS . 205 



