EXPERIMENTS IN MANURING IN POTS AND IN THE FIELD. 117 



On the DISCREPANCY BETWEEN the RESULTS 



OBTAINED by EXPERIMENTS in MANURING 



Etc. in POTS and in the FIELD. 



By Lionel Cohen, Chemical Laboratory, Department of 

 Agriculture, N.S.W. 



[Communicated by P. B. Guthrie, f.i.c, f.c.s.] 



before the Royal Society of N. S. Wales, July 7, 19091] 



The very marked results produced by the use of certain 

 manures on plants growing in culture pots and the enorm- 

 ously increased yield of crop, not seldom contrast strangely 

 with those from similar experiments using the same pro- 

 portions of fertiliser, the same variety of plant etc., when 

 carried out in the same soil under field conditions. No 

 entirely satisfactory explanation has, I believe, been 

 afforded of this phenomenon, the whole question being 

 considered, and rightly so, perhaps, as an extremely intri- 

 cate one, and one in which a large number of mutually 

 interacting physical and chemical forces have to be taken 

 into consideration. 



The problem of manuring in the light of water-supply 

 seems to have not received the attention in the observa- 

 tions and researches of many workers that the subject 

 deserves, and the questions of the application of fertilisers 

 to the soil, and of rainfall and irrigation have been studied 

 too much apart, but are really inextricably bound up one 

 in another. It seems to me that a very important factor 

 in the study of this matter has been somewhat overlooked, 

 namely the composition or state of concentration of the 

 solution from which the roots derive directly the nourish- 

 ment for the plant, in other words the soil moisture. 



