ON ACCUMULATION OF NITRATES 



83 



Lambourne End in 1919. The various phosphates were not sown 

 until January, 1919, and although clover was absent from all the 

 plots throughout the season, the treated plots gave almost twice 

 the yield of the untreated. The result was not due to any stimulation 



I" 



55 12 



a 



e 



g 



u 4 



22 



March 



f 19 

 April 



3 17 



May 



31 



J+ 28 

 June 



12 2 

 July 



3 29 



August 



e 20 

 Sept. 



FIG. 21. Nitrate content of the soil on the Untreated and Basic Slag Plots at Martin's 



Hearne. Soil Boulder clay. Season 1920. 

 Untreated Plot . Basic Slag Plot . Moisture Content 



6 2O 

 June July August Sept. 



FIG. 22. Nitrate content of the soil on the Untreated and Basic Slag Plots at Butcher's 



Farm, Lambourne End. Season 1920. Soil London Clay. 

 Untreated Plot . Basic Slag . Moisture Content 



of the clover, and as the crop was composed entirely of grass and 

 weeds, it seems probable that the much heavier crop on the treated 

 plots was mainly due to the direct effect of the phosphates in stimu- 

 lating the production of nitrates. 



62 



