rill': liLAcK WAI'I l.i: INDtSTKN'. 2^1 



ground nnburned till winter, and tlu-n, after liocin.ii^ all rank 

 herbage, securing an excellent burn, even ai the sacrifice of a 

 full crop of seedlings already r8 inches high. 



To many this would apj^ear wanton waste, and the loss of 

 nearly a season, but actually it acts in the op])osite direction, for 

 the growth on the well-burned ground more than coni])ensates 

 for the loss of the destroyed seeding croj), whicii on unburned 

 ground would sooner or later show the baneful effect of the 

 absence of fire. 



This brings us \.o another iini)ortant (|uestion as t(^ whether 

 or not the application of bacterial cultures to the soil has anv 

 effect upon the crop. 



The black wattle produces abundant nitrogenous nodules on 

 its roots, from its earliest stages onward, and in view of ex- 

 perience with other leguminous plants, clover, lucerne, etc.. it 

 has been held that the application of artificial cultures from 

 these nodules would facilitate the production of a crop, or woulrl 

 make unsuitable ground suitable for wattles. 



I had experiments made in this direction with carefully- 

 prepared laboratory cultures applied in fresh veld, but the results 

 gave nothing in favour of the culture. 



I feel satisfied that in all suitaljle wattle land in South .\frica 

 the bacterium is present, and was present before wattle existed 

 in South Africa; in other words, that the wattle has adopted an 

 ever-present indigenous bacterium ; or. i)erhaps, rather, that that 

 bacterium has adopted the wattle ; but that land unsuitable for 

 wattle is unsuitable for the bacterium also, and that no such 

 artificial bacterial application will in any way affect the crop, 

 either on the suitable or the unsuitable site, except possibly' in a 

 few rare cases not yet clearly understood. 



But in this connection the eft'ect of burning grass before 

 hrst ploughing, and of a thorough burn when renewing requires 

 scientific explanation. It does not seem likely that any bac- 

 terium on or close to the surface could endure these fires. ])Ut 

 it does seem likely that the fire sterilises the ground from in- 

 jurious bacteria, and at the same time gives a particularly su-it- 

 ablc charred and open medium, in which the favourable one finds 

 a suitable nidus. Whether it arrives from the air or from the 

 subsoil is not clear, but the regrowth and formation of nodules 

 ■ on a charred mass where a pile of refuse has been burned, irre- 

 spective of whether that pile was wattle wood or grass refuse, 

 shows within a month that the bacterium is present in abundance, 

 while the poorer growth on adjoining unburned s])ots shows that 

 it is not yet active there, and this early advantage is maintained 

 through life. 



But my experience does lead me to believe that the applica- 

 tion of ordinary complete fertilizers can be made with profit. 

 This is best seen where ground barely fit to carry mealies is well 

 fertilised on purpose to obtain a catch-crop of mealies between 

 the }-oung wattles during their first summer. Such catch-croii 

 usually pays the labour and manure, and the wattles uii- 

 doubtedly benefit from the residual manure and from the culti- 

 vation unavoidable with the niealie. 



