LOSSES OF MOISTURE AXD PLANT FOOD BY PERCOLATION. 



41 



QUANTITY OP NITRIC NITROGEN PERCOLATING. 



Table No. 16 is a summary of Table No. 14 and shows the total quan- 

 tities of nitric nitrogen percolating from the uncultivated soil both 

 those which received no additions and those which received manure 



An examination of the tables show that the concentration of the 

 nitrates in the water percolating from the pots reaches its maximum in 

 the tall usually m December, and its minimum in the spring usually 

 in April. This may be due to the accumulation of nitrates during the 

 summer months., when the temperature is favorable to nitrification? and 

 there is little percolation, and to washing the nitrates out by the fall 

 and winter rains. Nitrification is of course less active during the win- 

 ter months. From Table No. 14, showing the nitrates in milligrams 

 percolated per pot, we likewise see that the nitric nitrogen washed out 

 in December forms a large proportion of the total loss. ^ 



NITROGEN LOST IN POUNDS PER ACRE. 



^ The loss of 1 rag. per pot represents a loss of 0.122 pounds per acre. 

 Table No. 15 shows the average loss of nitrogen in pounds per acre per 

 year for the several soils (December, 1913, excluded). The loss varies 

 from 26.7 to 244.2 pounds per acre. The average for the sandy group is 

 67.2 pounds and for the clay group 168.6. The nitrogen content of soil 

 end subsoil is also stated in the table. It is seen that the loss of nitrates 

 is .related to the total nitrogen of the soil. The quantity increases with 

 the content of soil and subsoil in nitrogen. As it takes approximately 

 1.5 pounds nitrogen for grain, stalk, leaves, etc., for a. bushel of corn, 

 we have also calculated the loss of nitrogen to bushels corn per acre. 

 This is 45 bushels for the first group and 114 bushels for the second. 



TABLE NO. 15. 

 Loss of Nitric Nitrogen Per Year Per Acre. 



While it is not probable that all the nitrates produced were washed 

 from the soil each year, yet the figures ought to give us a fairly good 

 idea of the amount formed. We can also compare these figures with 

 the corn possibility based upon the nitrogen taken up in pot experiments 

 as follows : 



