Date of this Version
The influence of autoclaving and of fumigation with eight chemical formulations upon microbial numbers in straw-amended Peorian loess and the extent to which these treatments affect the degree of aggregation brought about by subsequently introduced inocula were determined. A mixed soil flora, Stachybotrys atra and a blank inoculum consisting of sterile salt solution, were compared. Only in the autoclaved soil was a mixed soil flora inoculum consistently superior to the blank inoculum in promoting aggregation of the Peorian loess. It was found that inoculation with S. atra could greatly increase the aggregation of fumigated Peorian loess in treatments where the fumigation was effective in reducing microbial numbers to a low level, and where the fumigant exerted little if any residual toxic effect upon the S. atra inoculum. Most promising of the fumigants tested were chloropicrin and Telone. The aggregation brought about by inoculation with S. atra in Peorian loess fumigated by appropriate amounts of either of these chemicals was approximately two-thirds as high as that produced by the same organism following autoclaving of the soil material.