370 NATURE AND PROPERTIES OP SOILS 



or less stable, except for slow solubility. In most cases, how- 

 ever, the carbonate, especially magnesium carbonate, is rap- 

 idly decomposed and carbon dioxide is given off, the bases 

 presumably entering the unsaturated aluminum silicates 

 w^hich are likely to be present in acid soils.^ 



The actual loss of lime in drainage water occurs through 

 the influence of carbon dioxide which changes the insoluble 

 carbonate to the soluble bicarbonate. The bicarbonate is 

 washed out as such or ionizes, the calcium and the magnesium 

 being lost in the ionic state. The presence of nitrates in the 

 soil, either from biological activity or from fertilizers, also 

 greatly facilitates the loss of lime from the soil in drainage. 

 Such influence is to be especially expected during the summer 

 and fall. In spite of the direct effect of carbon dioxide and 

 nitrates on the loss of lime, the controlling factor seems to be 

 the amount of water passing through the soil rather than its 

 concentration. The following unpublished data from the 

 Cornell University lysimeters show the losses of lime that may 

 be expected under different conditions.^ These figures are 

 averages of ten years ^ work with Dunkirk silty clay loam. 



Table LXXXIII 



aveeage annual loss of nitrogen and lime by leaching, 

 cornell lysimeters. average op 10 years. 



Condition 



Bare soil 

 Eotation. 

 Grass. . . 



Pounds to the Acke Per Year 



Nitrogen 



69.0 

 7.3 



LIMB EX- 

 PRESSED- AS 



CaO 



557.0 

 363.8 



LIME ES" 

 PRESSED AS 



CaCO, 



993.6 

 617.1 

 648.9 



* Maclntire, et al., The Non-existence of Magnesium Carbonate m 

 Sumid Soils; Tenn. Agr. Exp. Sta., Btil. 307, 1914. 

 = Complete data on these lysimeters will be found in par. 163. 



