306 THE PRINCIPLES OF SOIL MANAGEMENT 



Ammoniacal nitrogen in the drainage water is very 

 small in amount, but nitrate nitrogen is present in 

 amounts sufficient to make the loss of some concern. 

 The use of sodium nitrate occasioned the greatest loss 

 of nitrogen while ammonium salts and farm manure 

 contributed nearly as much. Forty to fifty pounds of 

 nitrogen per acre may be lost annually in this way, 

 which amount would have a commercial value of from 

 eight to nine dollars. 



The most serious losses are those of nitrogen and 

 lime, and both are to an extent unavoidable. Potassium 

 and phosphorus, which must also be purchased in ma- 

 nures, are lost only at the rate of a few pounds per acre 

 but had lime been applied to any of these plats, the loss 

 of potassium would probably have been larger. Nitro- 

 gen and phosphorus are best conserved by keeping 

 crops growing on land as much of the time as possible, 

 and the former may also be protected by applying the 

 soluble nitrogen salts only at a time when they can be 

 utilized by crops. The loss of calcium frequently amounts 

 to several hundred pounds per acre annually, and, as 

 the presence of calcium carbonate is essential to a 

 healthy condition, of the soil this loss, particularly 

 from the soil receiving salts like sulfates and chlorides, 

 the bases of which are absorbed by plants in larger 

 amounts than the acids, is likely to result in a very bad 

 condition of the soil. The only method of obviating this 

 is to lime the soil from time to time. 



170 Relation of absorptive capacity to productive- 

 ness. The absorptive capacity of a soil is not so much 

 a measure of its immediate as of its permanent produc- 



