Chemical Analysis of Hoils. 'M\ 



CHEMICAL ANALYSIS OF SOILS. 



B. DE ('. Makchand, 13. a., D.iSc, Chief, Divisiou ot Clieiiii.sU.> , 

 Depaitmeut of Agricultiiie. 



Farmeus iij Soutli Africa me apt to attach too little or too much 

 iinportance to .soil analysis. Those who do not submit samples of the 

 .soil from their farms for examination iu the laboratories of the Depart- 

 ment of Agriculture are not actuated, for the most part, by a disbelief 

 iu the value of such analyses, but apparently are merely neglectful or 

 ignorant of tlie facilities oftered. In many cases the farmer is satis- 

 fied with the yield obtained under his methods of cultiyation and does 

 not seek to obtain g-reater returns. Htliers, no doubt, are well aware 

 of tlie cajiacity of their soils for crop i)roduction and of the most 

 profitable manures to use, and have learnt by experience the most 

 suitable crops to grow. 



On file other hand, the belief in the value of soil analysis is by 

 some carried to extremes. The soil chemist is credited with almost 

 supernatural powers, such jjowers that if he really possessed them 

 would enabh' him to become a millionaire in a short space of time, 

 if he only hail the land to farm on. Frequently in the Division of 

 Chemistry we have a matchboxful of soil sent in. the sender writing' 

 from a box number in a big town, with the request that the soil be 

 analysed and a report furnished as to manures required, crops to 

 g-row, trees to plant, or if teif will do better than tall fescue, and so on. 



IVoAv if a soil chemist, say, in South Africa, were given a sam])l(' 

 of soil coming' from the West Indies, he would be able to determine 

 the quantities of the various plant food constituents present in tliaf 

 soil and ])robably to give reliable advice on a scheme of manuiing', bul 

 unless he knew where the sample came from, and were acquainted with 

 conditions in that locality, he would be utterly at sea on the question 

 of suitable crops or trees. The suitability of a particular crop to 

 particular soils only holds provided other conditions are the same. 

 Climate is one of the most important factors in the selection of the 

 crop. It would be absurd, for example, to say that a soil from the 

 high veld districts of the Transvaal was suitable for mangoes, yet as a 

 soil it mig'ht well be exactly similar to soils on which mangoes are 

 successfully grown in the low veld oi' Xatal. 



Yet many persons who submit samples of soil are positively 

 annoyed when asked for more information or even for a sample of 

 reasonable size. 



The object of this article is to attempt to indicate the limitations 

 as well as the value of soil analysis. 



In the laboratories of the Division of Chemistry two types of 

 chemical analysis of soils are carried out : (1) The so-called " com- 

 plete analysis," and (2) a partial analysis. 



We will briefly discuss these and endeavour to explain what is to 

 he learnt fjom them. 



