VELD-l!LRi\"lNG EXIMIKIMENTS AT (iROENKLOOF^ PRETORIA. 295 



of maize, wlioat and .urass and affurdins^ excellent pasture. The percent- 

 age composition of this soil (helow tiie 2 mm. grade) is as follows: — 



h'ine gravel. Sand. Silt. Clay. 

 .34 47 17 



It should be added that the Miami soils are derived directly from 

 the fine silty deposit as " loess '' — a friable calcareous loam, filled with 

 minute tubular pores which are lined with calcium carbonate. Chemically, 

 the Groenkloof soils differ considerably from this type. In fact, chemically, 

 the Groenkloof soils leave much to be desired, as the following analytical 

 results show : — 



Percentage of soil sifted through Percentage of soil sifted through 



I- mm. sieve. 

 Moisture Loss on Nitrogen Pot- Lime. Mag- Phosphoric Oxide 

 Ignition ash nesia. soluble soluble 



in cold in boiling 

 Hydro- Nitric 

 chloric and Sul- 

 Acid phuric 

 Acids. 



A. 1. 5 1 9.70 -148 .040 .060 .042 .029 -o8r 



B. 2.19 7.30 -123 .048 .104 .084 .050 -iiS 



C. 1.68 10.25 .149 .032 .046 037 .039 .093 



Except where otherwise stated, the inorganic plant food constituents 

 in the above table were extracted from the soil by means of cold hydro- 

 chloric acid. 



The moisture and loss on ignition were also determined in respect 

 of the soil as sifted through a half millimetre sieve, with the following 

 percentage results : — 



Moisture. Loss on Ignition- 



A. 1.52 8.83 



B 1.27 7-21 



C. 1.60 9.54 



These soils cannot be described as good from the chemical viewpoint : 

 their humus content is not very high, and accordingly the nitrogen per- 

 centage and retentive power for moisture are only fair. In all the 

 inorganic constituents of plant food they are defective, B. being the 

 least poor of the three, although the difference is really inappreciable. 



I should like to know as nearly as possible from which part of the 

 farm the samples were taken in order that any connection between the 

 soil and the underlying geological formation may be noted. The northern 

 and eastern portions of the farm comprise, I believe, quartzites and shales 

 of the Pretoria series, while the south-western part — roughly the part 

 south and west of Fountains — consists of dolomitic limestone and shales- 



(Sgd.) Chas. F. Juritz, 



Agricultural Research Chemist- 

 Charts showing maximum and minimum temperatures, and 

 rainfall and percentages of moisture in the soil are given on the 

 succeeding pages 296-299. 





IluI LIBRA R 



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