274 PRINCIPLES OF AGRICULTURAL CHEMISTRY 



12.0 pounds respectively, with an estimated gain of 5.0 pounds 

 nitrogen derived from rain and dew. From 2/9 to *4 of the 

 total loss of nitrogen passes into the drainage waters. 



Gains by Material Dissolved in Capillary Water. A certain 

 portion of the water which sinks into the subsoil, rises again to 

 be evaporated near the surface or transpired by plants. It has 

 been claimed that this water may bring dissolved material to the 

 surface soil. Such is indeed the case in arid regions where 

 soluble salts are within reach of the water. The alkali zone may 

 rise or sink to some extent with the dry or wet character of the 

 season. In humid sections, however, material is dissolved by the 

 water as it passes through the surface soil, and the gain can be 

 due only to a longer contact with the subsoil. There may be some 

 gain of this kind, but it would have to be considerable to counter- 

 balance the material dissolved in soil water which enters the 

 ground water and does not return to the surface. The writer has 

 been able to find no experimental data showing the relative 

 solubility of the material of soils and subsoils, and the relative 

 quantity of water which reaches the subsoil and which returns to 

 the surface. 



Losses by Washing. Water running off on the surface carries 

 soil particles with it, so that as a general rule the surface soil is 

 deeper in valleys and thinner on hill-sides. The particles are car- 

 ried to some extent in the water of streams, and may be deposited 

 elsewhere along the course of the stream, or carried to the sea. In 

 regions of heavy rapid rains, the running water may cut ravines 

 and gullies, and practically destroy unprotected hillside land. 

 Vegetation is a protection against such loss, and so is anything 

 which checks the rapidity of the flow of the water. Proper hill- 

 side terracing is the best treatment for cultivated land. 



Loss by Bacterial Action. The losses by bacterial action fall 

 on the organic matter and the nitrogen of the soil, none of the 

 other materials being directly lost in this way. Excessive nitri- 

 fication is followed by losses of nitrogen as nitrates in the drain- 

 age water, usually as calcium nitrate, which involves a loss of 

 lime, also. Nitrogen is also lost to the soil by denitrification, par- 



