217 



Phokwani Hills, 142. 



Phosphate starvation, 45. 



Phosphates, Lack of, 49, 59, 60, 63, 74, 89, 110, 114, 120, 121, 134, 146. 



retards nitrification, 23. 



Phosphoric oxide, available, 2. 



determination of, 7, 14, 15, 16, 17. 



European limits of adequacy differ from Colonial, 12, 49. 

 needed for cereals, 45, 47, 72, 114. 

 poverty of certain districts in, 4, 23, 32, 33. 

 scanty store of, may be compensated for by lime, 17 

 Physical classification of soils, variety of methods, 189, 190. 



,, composition of soils : (see also Mechanical analysis), 177, 188. 

 Physics, Soil, 5, 10, 11, 42. 

 Piquetberg Division, 20, 21, 107. 

 Plant food, 1, 2, 8. 



abundant in doleritic soils, 27, 28, 32, 53, 162. 

 and plant food constituents, difference between, 8, 9, 159. 



available, 2, 3, 7, 8, 9, 10, 12, 153, 159, 172, 188. 

 carried to the subsoil by rain, 172. 



constituents, determination of ; (see Soil constituents). 



,, ,, ,, third grade, Fluxes needed to extract, 9. 



,, various grades of, 9, 10. 



,, deficient in Malmesbury series soils, 158. 



Sandstone soils : (see Sandstone soils, Poverty of). 



,, derived from air, 1. 



,, ,, ,, ,, humus, 1. 



,, ,, ,, mineral constituents, 1, 2. 



,, ,, ,, ,, soil particles, 1. 



,, ,, ,, water, 1, 2. 



,, ,, how conveyed, 2. 



,, in soil, influence of geological relations on, 157. 



,, ,, mechanical fineness requisite, 1, 13, 188. 



,, ,, most abundant in finest grades of soil, 13, 188. 



,, ,, nitrogen as a source of, 1. 



of first grade, affects land's immediate productiveness, 10. 



,, ,, ,, brought to the surface by evaporation, 172. 



,, ,, of second grade, affects land's permanent value, 10. 



carried down to subsoil by rain, 172. 



percentages, soil classification on basis of, 17. 

 readily available, brought to the surface by evaporation, 172. 

 reserve stock of, 9, 10, 11, 12, 153, 155. 

 solvents of, 2 

 Plettenberg Bay, 67. 

 Pniel geological series, 163. 



soils, Analyses of, 163, 171. 



Port Nolloth, 95. 



Port St. John's District, 107, 171. 

 Portulacaria afra, 97. 

 Potash, determination of, 7, 8, 14, 16. 



proportion of, in certain soils, 120. 

 scanty store of, may be compensated for by lime, 17. 

 Potato soils, Physical composition of, 190, 192. 

 Potteberg, 31, 132. 



Pounding of soil furnishes misleading analytical results, 1' . 

 Pre-Cape rocks, 153, 161, 171. 

 Preparation of soil samples for analyses, 6. 

 Prieska Division, 20, 21, 60, 108, 171, 201. 



,, soils, Mechanical analyses of, 201, 202. 

 Productiveness and fertility, 2, 10, 18. 188. 

 Purple shales and mudstones, 89. 



Quarrie, Bredasdorp Division, 28, 30. 

 Queenstown Division, 19, 20, 21, 109, 146. 



Radio-activity, 1. 



Rain renders subsoils clayey, 192. 



Readily available plant food, 9, 10, 12. 



Reserve stock of plant food, 9, 10, 11, 12, 153, 155. 



,, ,, and objects of soil survey, 10. 



