372 SOILS: PEOPEBTIES AND MANAGEMENT 



278. Losses of nitrogen and calciiim. — The most 

 serious losses of plant nutrients in the drainage water of 

 soils are those of nitrogen and calcium, and both are to 

 an extent unavoidable. Potassium and phosphorus, 

 which must also be purchased in manures, are lost only 

 at the rate of a few pounds to the acre. Nitrogen and 

 calcium may be conserved by maintaining a crop on the 

 soil continually. A large removal of nitrogen in the 

 drainage water is usually accompanied by a large re- 

 moval of calcium ; for nitrogen is leached from the soil 

 mainly in the form of nitric acid, which of course com- 

 bines with a base, and calcium being the base finally 

 liberated it is carried off in drainage water. While most 

 of the calcium in drainage water is in the form of bicar- 

 bonate, the cpantity is greatly increased by nitric acid. 



The relation of nitric acid to calcium in drainage water 

 is shown by experiments with soil in large tanks from which 

 drainage water was collected. Plants were grown in the 

 soil of certain tanks, while others had none, other conditions 

 being similar. Analyses of the drainage water at Ithaca, 

 New York, as reported by Lyon and BizzelF show a greatly 

 increased loss of calcium from the unplanted tanks, from 

 which the loss of nitrate nitrogen was also much greater : — 



Nitrogen and Calcium IIe.moved in Drainage Water be- 

 tween May 23, 1910, and May 1, 1911. Calculated to 

 Pounds to the Acre 



Crop Gkown 



Nitrate Nitrogen 



Calcium 



None 



Maize 



Oats 



119.6 

 10.8 

 12 5 



406.7 

 158 

 173.4 



^ Lyon, T. L., and Bizzell, J. A. Composition of the Drain- 

 age Water of a Soil with and without Vegetation. Jour. Indus, 

 a-nd Eng. Chem., Vol. 3, pp. 742-743. 1911, 



