LOSS OF CALCIUM CARBONATE 



289 



with carbonic acid exhaled from the roots or arising from the 

 decay of organic matter in the soil. Of course, there are 

 many factors which might modify this figure in other soils ; 

 it must to some extent depend on the actual amount of 

 carbonate of lime in the soil, on the magnitude of the drainage 

 through the soil this being lessened with larger crops on 

 normally manured land and also on the proportion of carbonic 

 acid in the soil gases, which proportion would be increased 

 with manured soil and larger crops. Still these are the best, 

 indeed the only figures available to show the loss of carbonate 

 of lime that arable land is likely to suffer, and we may now 



TABLE XCYII. Loss of Carbonate of Lime from Eothamsted Salts. 



* Another plot, more fairly comparable with the plots which follow, lost at the rate of 675 Ib. per acre. 



proceed to consider how far the loss is affected by the use 

 of ammonium- salts as manures. At Rothamsted a mixture 

 of sulphate and muriate of ammonia has always been 

 employed, and though certain minor differences may be 

 traced in the action of the two fertilisers, in the main the 

 two together will behave towards the soil of the plant just 

 like sulphate of ammonia alone, though in a slightly more 

 concentrated form. The table only gives a selection of the 

 plots from which results are available (for details see Hall 

 and Miller, Proc. Roy. Soc., B. 77 (1907), 1), but it is clear 

 that the use of ammonium-salts causes increased washing 

 out of the carbonate of lime ; in fact, from the original figures 



