28o SOIL CONDITIONS AND PLANT GROWTH 



another great group of organisms, and which we must now 

 proceed to discuss. 



Investigation on the Partial Sterilisation of the Soil. 



The earliest observations that soil is altered by an ap- 

 parently inert antiseptic arose out of attempts to kill insect 



Le R^veil de la Terre (Muntz and Gaudechon) 



Rate of Nitrification, 

 teoo 



800 



400 



Feb AprJ . May Feb. Apnl 



'* Terre ^ Terreau 



Bacterial numbers in soil : plots ib and 4B. Cropped with millet • uiimanured. 

 (The curve showing moisture content is very similar to that for 4B.) (Conn.) 

 Fig. 27. — Bacterial activity in soils at different seasons of the year. 



pests in the soil by means of carbon disulphide. This sub- 

 stance, which for fifty years has been known as an insecticide, 

 was usecf in 1877 by Oberlin,^ an Alsatian vine-grower, 



^ Boden-MUdi gkeit und Schwefelkohlenstoff, Mainz, 1894. 



