L. J. Wild ' 155 



assistance in elucidating an important problem for agriculturists in New 

 Zealand. 



B. Laboratory Experiments. 



After making a few sets of experiments, it was noticed tliat deter- 

 minations made at different times on the same soil gave different results. 

 Thus the following figures for the percentage lime requirement of 

 Field 2P have been obtained on different occasions: 0-14; 0-15; 0-17; 

 0-18 ; expressed .in lbs. per acre, the range is from 1900 lbs. to 2400 lbs., 

 that is, the highest figure is more than 25 % greater than the lowest. 

 It was recognised however that the determinations which failed to 

 agree had been made under different conditions as to volume and 

 strength of bicarbonate solution, and so it seemed necessary to make 

 sets of determinations simultaneously on one soil under uniform con- 

 ditions. Results of such are shown in Table I. 



Table I. 



In sets B and C 400 c.c. of solution was used ; in set A only 300 c.c. 

 the strength of which was also rather less than in the case of the other 

 sets. 



As a further test, three samples of soil from Field 16 were treated 

 simultaneously — A with 300 c.c. of solution of strength 0^02 N ; B with 

 400 c.c. of the same strength ; C with 400 c.c. of strength 0-014 N. 

 The lime requirements indicated in these three cases were: A, 0-11 %; 

 B, 0*12 % ; C, 0-05 % . It seems therefore that the volume of solution 

 may be varied within fairly wide limits without affecting the result, 

 provided that the solution does not at any time fall below a certain 

 concentration. This is obviously a suggestive point which merits 

 further investigation, and is again referred to later on. 



^ AH fields mentioned lierein are those of the Canterbury Agricultural College Farm. 

 Journ. of Agric. Sci vni 1 1 



