556 NATURE AND PROPERTIES OF SOILS 



pounds each year to the acre-four feet. It is evident, there- 

 fore, that the losses sustained by the average soil fall most 

 heavily on the organic constituents, a condition often ignored 

 in practical soil management. The removal of calcium oxide is 

 also very large, being equivalent to a loss of 661 pounds of 

 calcium carbonate an acre a year. Although losses of sulfur 

 trioxide and phosphoric acid are smaller than that of the 

 potash, they are far more important, since there is very com- 

 monly one hundred times more potash in a soil than of the 

 other two constituents combined. The magnitude of the loss 

 of a soil constituent is never a safe measure of its importance. 

 The removal of nitrogen is equivalent to over 500 pounds of 

 commercial sodium nitrate and consequently is also a loss of no 

 small consideration. 



319. Additions of nutrients to the soil. — The figures 

 presented above are based on reliable experimental data. Un- 

 fortunately the information regarding the additions which 

 normally occur to a soil under any particular rotation are by 

 no means so exact. Certain assumptions and estimates, often 

 of questionable validity, must be admitted in order that a 

 complete survey may be possible. Table CXXIX sets forth 

 the additions which the Dunkirk clay loam of the Cornell lysi- 

 meters may reasonably be expected to receive each year when 

 cropped to a five-year rotation of maize, oats, wheat, and two 

 years hay. The data are expressed in pounds to the acre a 

 year. (See Table CXXIX, page 557.) 



The additions listed above are not the only avenues open 

 for important acquisitions. The crops removed may be fed to 

 animals and the manure returned to the land. Moreover, the 

 utilization of a green-manure is also possible. Below will be 

 found the additions that may reasonably be expected from the 



Jersey. The rotation was maize, oats, wheat, and two years hay. No 

 lime was added. 



Lipman, J. G., and Blair, A. W., The Lime Factor in Permanent 

 Soil Improvement. I. Rotations Without Legumes; Soil Sci., Vol. 

 IX, No. 2, p. 87, 1921. 



