144 



Partial Stenlisation of Soil 



Table 15. 



Series 1. Crops grown without addition of nitrifying organisms. 



where nitrate is being produced in the soil and presumably forms the 

 chief nitrogenous food of the plant, i.e. in the untreated soil, and the 

 untreated and toluened soils inoculated with the nitrifying organism. 

 It is higher where no nitrate is being formed, i.e. in the two heated 

 soils and the uninoculated toluened soil. The introduction of the 

 nitrifying organism into the heated soil has had little or no effect in 

 reducing the percentage of nitrogen in the dry matter of the plants. 

 Wheat behaves differently, and requires further investigation. 



Nitrification is therefore not essential to plants, but it may be 

 economical. A greater weight of dry matter is formed for each unit 

 of nitrogen assimilated as nitrate than as other compounds. 



§ 45. Whilst the first crop was growing the nitrifying organisms 

 inoculated into the heated failed to develope, being inhibited, probably, 

 by a toxic body (§ 31). But during the time the second crop was 

 growing the added organisms developed abundantly, a result suggesting 

 that the toxic body slowly disappears from the soil. 



