68 EFFECT OF PHOSPHATES 



moister than on the untreated plot, throughout the dry periods, the 

 opposite was the case as far as the moisture content of the 3rd to 

 9th inch was concerned. Whenever a period of wet weather succeeded 

 a dry spell, as for example during June 14th to 21st, the moisture 

 content on both plots at a depth of 3-9 inches rose to approximately the 

 same level. A dry spell invariably resulted in the moisture content of 

 the 3rd to 9th inch on Plot 17 falling more rapidly than on the un- 

 treated plot. In view therefore of the high moisture contents which 

 have prevailed at various periods throughout the season, it seems 

 evident that the crop on Plot 17 has been able to utilise the moisture 

 at this depth, particularly during dry spells, to a much greater extent 

 than was the case on the untreated plot. Mechanical analysis 

 (admittedly imperfect for this purpose) fails to detect any difference 

 in the mechanical structure of the soil on these two plots, and it is 

 therefore probable that during the first years which follow the appli- 

 cation of basic phosphate to this type of meadow land, the crop on 

 the slag plot is able to draw upon the moisture content of the soil at 

 lower depths than is the case on the untreated plot largely because of 

 the increased root development. The behaviour of the two plots from 

 August 16th, when the plots were cut, until September 20th 1 tends 

 to confirm this view. It will be seen that the moisture content of 

 the section of the soil from 3-9 inches remained practically the same 

 on both plots during this period and as far as the eye could judge 

 no growth took place. 



TEMPERATURE 



The temperature records were taken by means of a special thermo- 

 meter recording between and 30 C., and graduated to one-tenth 

 of a degree. During the latter stages of the work this thermometer 

 was replaced by one registering only to one-fifth of a degree. It was, 

 however, a simple matter to get results to one-tenth of a degree by 

 interpolation. 



The temperature records of the soil on Plots 16 and 17 are given 

 in Table XXXVI and are recorded graphically in Figs. 15 and 16. 

 Examined in conjunction with the figures in Table XXXV (repre- 

 sented in Figs. 13 and 14) the results have an important bearing 

 upon the action of slag under dry climatic conditions on such heavy 

 London clay soils. During the whole of the period from May 17th 

 till the crop was carted off the plots on August 21st, the surface three 



1 Unfortunately the sample drawn from Plot 17 on August 31st met with an 

 accident. 



