226 VVriEAT SOILS OF THK ALl-.XA N 1)K 1 A DIVISION. 



The salient facts shown by the above table are first of all 

 that, from the point of view of cjcneral crop-raising, the only two 

 constituents in which these soils may be said to be really deficient 

 ?re potash and.phosphatic material. One or other of these is 

 present in too small quantity in 13 out of the 20 soils sampled; 

 and it must be remembered that abundance of some other 

 constituent — such as nitrogen, for instance — cannot atone for 

 deficiencies like these; if anything, its very abundance only 

 accentuates the lack, and may even help to exhaust the soil of the 

 deficient constituents all the more rapidly. The next broad 

 feature is that in several cases cultivation has removed from 

 the soil plant food constituents which were present in larger 

 proportion in the virgin soil. Compare, for example, the per- 

 centages of lime and nitrogen in sam])le No. i with those in 

 No. 2; the proportions of lime and potash in No. 4 with their 

 ])roportions in No. 3. Betw-een Nos. 5 and 6 no such deteriora- 

 tion is noticeable, but the cause of this divergence may lie in the 

 thorough turning up of the soil by deep i:)loughing, as already 

 suggested. 



Of the virgin soils, which represent the lands in their original 

 condition, it becomes evident, from the foregoing results, that 

 Nos. 8 and t2. which contain the largest proportions of lime, 

 are also the richest in nitrogen and ])hosphates, and contain more 

 moisture and organic matter than any other virgin soils of the 

 series ; in fact, there is a close j^arallelism between the propor- 

 tions of water, organic matter and nitrogen — and to a certain 

 extent also })hos])horic oxide — all through the series, Nos. 8, 

 12, 14, 16, 20 and 2 forming the better group, and Nos. 4, 18, 

 10 and 6 the worse. Another ])arallelism is noticeable between 

 the magnesia and pota.sh in the soil, the largest quantities of both 

 being fcmnd in Nos. 2 and 4, along the banks of the Bushman's 

 Ri\cr, and the least in Nos. 18 and 10. while there is an inter- 

 mediate grouj) comprising Nos. 16, 12, 14, 20, 6 and 8. 



There is at least a fair amount of nitrogen in all the soils, 

 and in Nos. 7, 8, 11 and 12 the pr(^i)ortion is really good, but 

 for wheat soils a larger ])roportion of nitrogen would be a decided 

 ;.dva!itage. .\11 the soils alsr> contain at least a moderate pro- 

 ])(>rti()n of lime, while Nos. 13 and 14 contain a good (|uantity, 

 and Nos. 11, t2. 19 and 20 are rich in this respect. Nos. 7, 8, 

 9, 10, 17 and 18 are poor in potash, and none of the other samples 

 ! howed more than a fair proportion except Nos. i and 2, in 

 which the anKUint of potash is satisfactory. As to phosphorus 

 pentoxide, Nos. 1. 2. 19 and 20 have a fair amount. Nos. 6, 7. 

 I r and 12 are good, and the virgin soil No. 16 contains a moderate 

 iorr)portion ; but all the other soils are poor in this respect, Nos. 

 17 and i8 particularly so. 



Magiiesia is also an essential plant food, but several recent 

 investigations tend to show that in some cases it may cause 

 injury to crojjs if its proportion is greater or not much less than 



I'age 226, 7th line from bottom. For "6, 7" read "7, 8." 



