210 



NATUEB AND PROPERTIES OF SOILS 



Table XLI 



average annual loss of nuteients by percolation from 

 bare and cropped soils. cornell lysimeteb tanks. 



Conditions 



Annual Loss in Pounds an Acre 





NITROGEN 



CALCIUM 



POTASSIUM 



Dunkirk clay loam : 

 Bare 



69.0 

 7.3 

 2.5 



51.8 

 10.2 



397.9 

 247.1 

 259.9 



341.4 

 356.4 



72.0 



Rotation 



Grass 



Volusia silt loam: 

 Bare 



57.3 

 61.7 



84.5 



Cropped. 



73.2 



The influence of the crop on percolation is obvious, the loss 

 of water by drainage being markedly decreased. The 

 saving of nutrient is also very marked, especially as regards 

 the nitrogen. The loss of nitrogen is only about one-seventh 

 as much from the soils under a rotation, as where the land 

 was bare, while the saving of calcium and potassium is con- 

 siderable. The importance of catch- and cover-crops in eco- 

 nomical soil management need not be emphasized further. 



110. Drainage.^ — ^While percolation, especially in hu- 

 mid regions, causes the loss of a large proportion of the 

 rainfall received and carries away in addition many tons of 



^Klippart, J. H., Principles and Practice of Land Drainage; Cin- 

 cinnati, 1894. 



Miles, M,, Land Drainage; New York, 1897. 



Faure, L., Drainage et Assainissement Agricole des Terres; Paris, 

 1903. 



Elliott, C. Gr., Drainage of Farm Lands; XT. S. Dept. Agv., Farmers' 

 BuL 187, 1904. 



King, F. H., Irrigation and Drainage, Revised Edition; Part IT, New 

 York, 1909. " 



Warren, G. M., Tidal Marshes and their Eeclamation; IT. S. Dept. 

 Agr., Office Exp. Sta., Bui. 240, 1911. 



Woodward, S. M., Land Drainage hy Means of Pumps; U. S. Dept. 

 Agr., Office Exp. Sta., Bui. 243, 1911. 



Elliott, C. G., Engineering for Land Drainage; New York, 1912. 



Parsons, J. L.^ Land Drainage; Chicago, 1915. 



