822 CONTRIBUTIONS TO OUR KNOWLEDGE OF SOIL-FERTILITY, 



It has been shov4fn that wax-solvents induce a segregation of 

 the agricere, and enable the soil-nutrients to be dissolved in 

 water, and made available for bacteria. There is, however, the- 

 possibility that the solvent may have an action of its own upon 

 the soil-toxin, either in destroying it or causing its segregation .- 

 In the latter case, the increased liberation of the nutrients may 

 counteract the depressing action of the toxin. A number of 

 experiments have been made in this direction, and will be con- 

 sidered in another paper of this series. 



The Action of Sunlight. 

 The fertilising action of sunlight is a matter that has raised 

 some discussion, and the general opinion is that it has a distinct 

 effect upon the fertility of a soil. As the question appeared to 

 be related to the destruction of toxin, two experiments were 

 made to determine the truth of the belief. In the first, the 

 portions of soil, a rich orchard soil from the Kurrajong, were 

 spread out on |)a{)er in the garden. One portion was covered 

 with black calico, the other was exposed to the sun. Both were 

 under glass frames to prevent the soil being blown away with 

 the wind. The extracts were made with distilled water in the 

 usual proportion and time (200 grm., 200 c.c, 1 hour). 



Experiment xi. 



It is evident that sunlight has a strong destructive action upon 

 the soil-toxin. 



