CHEMICAL COMPOSITION OF KARROO ASH. 1 37 



amount of earthy material which it contained. Nos. 6 and 7 

 were received in the unburnt state, and were carefully reduced 

 to ash in the laboratory, a circumstance which accounts in part 

 for the high proportion of fertilising constituents found in the 

 Fraserburg sample. The amount of the undesirable chlorine, 

 it will be seen, had been reduced to less than half that of the 

 previous sample from that locality. No. 7, before burning, was 

 found to yield 22.37 P^'" cent, of ash, and only .34 per cent, of 

 nitrogen, which shows that there would have been no advantage 

 worth considering in transporting it any distance in the unburnt 

 condition. 



When the preliminary investigations had reached the stage 

 above indicated, the facts elicited thereby were placed before 

 the Fruit-Growers' Congress which met at Worcester during 

 May, 1899, whence they passed to the Cape Horticultural Board, 

 and, in response to resolutions passed by those bodies, steps 

 were taken to procure specimens of kraal manure from different 

 parts of the Colony, for the purpose of ascertaining the pro- 

 portion of ash which they were capable of yielding, and of 

 determining the manurial value of the ash. It had been 

 generally realised that the bulkiness of the unburnt kraal manure 

 rendered its transport by rail very costly, and it was thought 

 that the reduction in bulk conse(|uent on liurning might, without 

 causing excessive loss of valuable constituents,'^ so facilitate 

 transport as to place the resulting ash within easy reach of 

 localities where its use would be advantageous. Aided by the 

 co-oj^eration of Mr. A. G. Davison, at that time Chief Inspector 

 of Sheep for the Colony, representative samples of kraal manure 

 were obtained from the Divisions of Cradock, Beaufort West, 

 Colesberg, Steynsburg, Aberdeen, Graaft'-Reinet, ^liddelburg, 

 Laingsburg, and Swellendam, and, in addition, samples of farm- 

 burnt Karroo ash were obtained from Middelburg. Klipplaat 

 (Jansenville Division), and V'ictoria West. These samples 

 exhibited considerable variation in degree of desiccation and 

 state of disintegration ,t and their analysis, entrusted to Dr. J. 



* When an article like kraal manure is burnt, tlie inorganic plant food 

 materials — potash, lime, phosphorus pentoxide — become concentrated in 

 the ash, and are at the same time reduced to so finely divided a condition 

 that they are, after burning, in a state well adapted for absorption by 

 plants. On the other hand, all the organic matter in the manure is 

 destroyed, including tiie nitrogen, which is a most valuable plant food. 

 Hence those beneficial effects which the addition of organic matter to 

 some classes of soil confers arc sacrificed by burning. There are, how- 

 ever, soils which already contain excessive quantities of organic matter, 

 and are acid or " sour " in consequence. For such soils the disadvantages 

 of adding more organic matter are obviated by reducing the manure to 

 ash. 



t Many of them were saturated with moisture, and would therefore 

 have had to be submitted to thorough drying before being transported m 

 bulk. Others were in large matted lumps, while others again were dry and 

 in an excellently fine state of division. Xot only the chemical composi- 

 tion, but also factors such as those just mentioned, influence tiie value of 

 the raw article. 



