1905.] 



On the Retention of Bases by the Soil. 



15 



necessary to bring the chalk into solution ; as a rule the soil gases get richer 

 in carbon dioxide the greater the depth, but the soil of the gauge is cut off 

 from the subsoil and open to the atmosphere at the 60-inch depth. The long 

 absence of any crop or manure will have reduced to very small limits the 

 amount both of organic matter decaying to carbon dioxide, and the organic 

 sulphur compounds which by bacterial action become sulphuric acid and leave 

 the soil as calcium sulphate. These causes will co-operate to lessen the 

 removal of calcium carbonate from the soil in the gauge, and as a matter of 

 fact the concentration of 53*5 parts of CaO per million observed in its 

 drainage is only about half of the concentration of the water running from 

 the tile-drains beneath the unmanured plot in Broadbalk, which according to 

 Voelcker's and Frankland's analyses (Table X) amounted in the mean to 

 about 99 parts per million. But assuming that this latter figure represents 

 the average proportion of lime in the drainage water from the unmanured 

 plot, and that the average annual percolation through the soil of this plot is 

 10 inches,* equal to that through the 60-inch gauge, the annual loss of calcium 

 carbonate per acre should amount to 400 lbs. for the unmanured plot instead 

 of the 800 lbs. found by analysis of the soil of the plot. The number of 

 analyses, however, upon which the former estimate is based, is too small for 

 great accuracy. 



Table X. — Broadbalk Drainage Water. 

 Mean of 10 analyses by Voelcker and Frankland. Parts per million. 



Plot. 



2 



3 and 4 



5 



6 



% 



8 



9 

 10 

 11 



Manures. 



Farmyard manure (14 tons) 



Unmanured 



Minerals only 



,, + 200 lbs. ammonium salts 

 + 400 lbs. „ „ 



„ + 600 lbs. 



„ + 275 lbs. nitrate of soda . . . 



400 lbs. ammonium salts alone 



„ „ + superphosphate 



Total solid 

 matter. 



367 

 227 

 329 

 450 

 542 

 615 

 405 

 441 

 490 



Lime and 

 magnesia. 



123 

 99 

 132 

 171 

 207 

 222 

 126 

 173 

 197 



In a paper by Creydt, von Seelhorst, and Wilmsf on the composition of 

 the drainage waters from an ordinary field tile-drained at a depth of 



* Ten inches was the estimate formed by Lawes, Gilbert and Warington, 'Journ. 

 Roy. Agri. Soc.,' 1882, vol. 43, p. 24 ; "Warington, ' Trans. Highland and Agri. Soc.,' 

 1905, vol. 17, 5th series, p. 168, estimates the drainage as somewhat more than 8 - 2 inches, 

 while a comparison between the concentration of chlorine in the water from the unmanured 

 plot and from the 60-inch drain gauge would lead to an estimated drainage of 9 inches. 



t ' Journ. der Landw.,' 1901, p. 251. 



