IV. 



THE REACTIONS OCCUEEING IN SOILS 



75 



nitrogen per acre (almost equivalent to that produced on fallow) 

 with those with wheat (case 10), early growth during somewhat dry 

 period ; the crop is here estimated to contain 54 -5 Ib. nitrogen per 

 acre, which, added to the amount lost in drainage, 29 '7 Ib., makes a 

 total for amount of nitrogen converted into nitrates of only 84*2 Ib. ; 

 less than half that produced on the fallow cases.] 



With reference to the loss of other constituents in drainage waters, 

 Stoklasa l has determined the amount of calcium carbonate in 

 drainage waters from soils derived from primitive rocks, from chalk, 

 and from peaty soils. He estimates the yearly loss of calcium car- 

 bonate in soils from primitive rocks at over 560 kilos per hectare (500 

 Ib. per acre) 2 and at about 3000 kilos per hectare (2700 Ib. per acre) 

 in soils from chalk. Its amount is increased by the application of 

 ammonium compounds, owing to the acid of these salts being con- 

 verted into calcium salts by interaction with calcium carbonate, and 

 also to the formation of the very soluble calcium nitrate from nitrifica- 

 tion. He also gives the amounts of phosphoric acid found in the 

 drainage water from (1) loam from granite and gneiss formations, (2) 

 clay from the Permian, (3) marl, (4) humic soil. The results were as 

 follows : 



This shows the enormous loss of phosphoric acid from humic soils, 

 although they contain only very small quantities. This great loss is 

 doubtless due to the solvent action of the large quantities of carbon 

 dioxide contained in the drainage of such soils. 



Hall 3 estimates the annual loss of calcium carbonate from an 

 arable, unmanured soil containing 1 per cent of this substance, at 800 

 to 1000 Ib. per acre ; the loss is increased by the use of ammonium 

 salts but diminished by application of sodium nitrate. 



Few determinations of the amount of potash in drainage waters 

 have been published. 



Its amount is probably always very small and the loss of potash 

 from this cause is seldom a matter of much importance. Any potash 

 which becomes soluble, or is applied in a soluble form as manure, 

 appears to be, to a great extent, held firmly in the upper layers of the 

 soil. 4 



On the other hand, American investigators found as much as from 

 0-43 to 44*0 parts of potash (K 2 0) in a million of drainage water. 5 



iLandwirth. Versuchs. Stat., 1894, 45, 161. 



2 Lawes, Gilbert and Warington (Jour. Roy. Agric. Soc., 1882, 1), estimate the 

 loss at about half this at Rothamsted, on unmanured land. 



3 Brit. Ass. Report, 1905, sect. B. 



4 H. Liebig, Jour. Chem. Soc., 1872, 318. 



5 Massachusetts State Station Report, 1883, p. 27. 



