440 Journal of the Department op Agriculture. 



of preventing the soil from becoming acid or of correcting acidity, if 

 such has already developed. 



Coming to the analytical features of the samples, it is found 

 that No. 612 contains a moderate quantity of clay, little fine silt and 

 silt, much fine and much coarse sand; viz., it contains much material 

 which allows of but little which prevents the movement of air and 

 water. The soil should therefore be one of high permeability ; the 

 figure (3.35) in Table I shows that such is actually the case. Owing 

 to the large percentage of fine sand (55 per cent.), this soil would 

 probably harden at the surface on drying. No. 613 contains less of 

 both grades of sand, the same amount of clay and about three times 

 as much fine silt and silt; viz., the soil contains considerably less 

 material which facilitates and more which hinders the movements 

 of air and water. These facts find reflection in the analysis which 

 gives the permeability as 0.53, or only one-sixth of that of No. 612. 



Apart from permeability, owing to the high percentage of coarse 

 particles in No. 612, the soil must be of low retentive power, both 

 as regards moisture and plant food, while No. 613 with its higher 

 percentage of finer particles will be raore retentive. One would 

 deduce from the analysis that No. 613 is the more desirable of the 

 two, and that 612, unless it be underlain by a more retentive sub-soil, 

 would be Jikely to suffer from drought unless the rains fell frequently. 



We shall see presently that from the chemical point of view, No. 



613 is also the better soil. 



In No. 614, both clay and silt are considerably higher than in 

 either of the preceding samples, and both coarse and fine sand are 

 considerably less. The further fall in permeability shown by the 

 analysis is therefore understandable ; one might, indeed, have 

 expected an even greater fall were it not that No. 614 contains about 

 twice as much humus as No. 613, the effect of humus being to keep 

 the clay soil in a granulated condition (vide svpra). 



The higher percentages of finest particles and of humus in No. 



614 make it a more retentive soil than No. 613, much more retentive 

 ■than No. 612. 



In wet seasons, if such are ever experienced in the Witkop 

 district. No. 614 would probably retain too much Avater; No. 612 no 

 more than sufficient. In average seasons, crops might suffer from 

 drought on No. 614, because that soil would be likely not to absorb 

 a sufficiency of the rainfall, while No. 612 would also carrj^ too little 

 moisture, because it has no great power of retention. No. 613, by 

 absorbing fairly well and retaining well what it absorbs, would prob- 

 ably be in a position in an average season to supply crops better with 

 moisture than either of the others. 



*A1] three soils are deficient in carbonates and are acid; that is, 

 they contain a harmful factor. 



Chemical Analysis. 



Nitrogen. — No. 614 contains twice as much nitrogen as No. 612, 

 No. 613 occupying an intermediate position. So far as our experience 

 goes, the nitrogen supply would seem to be ample in all cases. 



Lime. — In no case does the supply of lime appear inadequate 

 for food pui'poses. Note that the soil in No. 614 derived from the 

 dolerite-c?pped sandstone ridge is the richest in lime. 



Magnesia. — The remarks under " lime " apply here also. Note 

 also that the mechanical analysis returns the amount of carbonates 



