562 PEOCEEDINGS OF SECTION G2. 



of the solution were placed in conical flasks of 450 cc. capacity^ 

 and sterilised in the usual way. To each were added 0-4 grs. of 

 sterilised calcium carbonate and exactly 0-4 grs. of each of the soils 

 under investigation. The flasks were then put in an incubator at 

 29 to 30° C.,and the solutions were tested from time to time for the 

 presence of ammonia, nitrites and nitrates. 



It is not my intention to give a full account of the results, 

 the details of which will be found in the Annual Report of the 

 Director of Agriculture for the Transvaal for the year 1907-08. 



Briefly, however, the results were as follows : — ^The experiments 

 were conducted with 21 soils, varying from poor sandy soils to stiff 

 black clays. Nitrites and traces of nitrates were found in all the 

 solutions within a fortnight. In periods varying from 19 to 32 

 days and averaging 25 days from the time of inoculation, all the 

 ammonia contained in the solutions had been changed. In from 28 

 to 46 days nitrification was complete, all the nitrogen present in 

 the solutions being in the form of nitrates, the average length of 

 time taken for the completion of the reaction being 39 days. 



The incubation temperature, strength and volume of solutions, 

 etc., were purposely chosen so that the experiments might be 

 comparable with some of a similar nature conducted at Rothamsted 

 by Ashby. (See Journal of Chemical Society, 1904.) In the 

 English experiments nitrites were seldom present in the solutions 

 within a fortnight and rarely in three weeks, in 30 to 35 days the 

 bulk of the nitrogen was still in the form of ammonia, and nitrifica- 

 tion was often incomplete in 60 days. 



It seems therefore reasonable to conclude that the nitrifying 

 organisms are present in larger numbers or in a more active form, 

 or both, in the soils of the High Veldt of the Transvaal than in 

 England, and that with the higher average temperature prevailing 

 in the former country they perform their functions much more 

 rapidly and efficiently, and there is a strong probability that the 

 same is true of Australia, where the climatic conditions are similar, 

 namely in the semi-arid areas. Whether the increased activity is 

 purely a question of temperature, or whether it has something to do 

 with the generally drier conditions of the soil being less favourable 

 to the enemies of bacteria (protozoa), than the bacteria to them- 

 selves is a matter for further investigation. 



8.— ON THE PROPORTION OF FERROUS SULPHATE USED AGAINST 

 THE " WHITE ROT " OF GRAPE VINES. 



By M. BLUNNO, Department of Agriculture, Sydney. 



It is generally known that the " pourridie," or white rot of the 

 root system of the grape vine, is principally caused by a fungus 



