210 NATURE AND PROPERTIES OF SOILS 



Table XLI 



AVERAGE ANNUAL LOSS OF NUTRIENTS BY PERCOLATION FROM 

 BARE AND CROPPED SOILS. CORNELL LYSIMETER TANKS. 



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. 1 — 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 



1 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. G., Drainage of Farm Lands; U. S. Dept. Agr., Farmers' 

 Bui. 187, 1904. 



King, F. H., Irrigation and Drainage, Eevised Edition; Part II, New 

 York, 1909. ' 



Warren, G. M., Tidal Marshes and their Reclamation; U. S. Dept. 

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



Woodward, S. M., Land Drainage oy 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. 



