Viii.j LOSSES TO SOIL IN DRAINAGE WATERS 2S5 



of water, the unmanured plot will lose about 220 lbs. 

 per acre per annum of lime : equivalent to about 400 lbs. 

 of carbonate of lime, whereas the analysis of the soil 

 shows (p. 216) an annual loss of about 800 lbs. per acre. 

 The discrepancy between these two figures is due to the 

 fact that the results are calculated from but a small 

 number of analyses of the drainage water, the amount 

 of which is also very uncertain. When 400 lbs. of 

 ammonium salts are used as manure, either alone or 

 with minerals, the increased loss of lime calculated on 

 the same basis amounts to 126 lbs. or 225 lbs. of 

 carbonate of lime per acre per annum, as against about 

 240 lbs. found from the analysis of the soil. 



The amount of magnesia lost is small, 5 to 20 lbs. 

 per acre per annum, nor is the amount reaching the 

 drainage water much increased by its application as 

 manure to plots 5, 6, 7, 9, and 14. 



The amount of potash lost is still smaller, from 

 3 to 12 lbs. per acre per annum, but it is distinctly 

 dependent on the amount supplied as manure, being 

 at a maximum with the dunged plot (2) and the plot 

 receiving minerals only (5), and greater from all the 

 other plots receiving potash than from those without 

 it, i.e., 3, 10, 11, 12, 14. The use of sulphate or 

 nitrate of soda increases the amount of potash in the 

 drainage water, not so, however, the use of sulphate 

 of magnesia. Practically all the soda, chlorine, and 

 nearly all the sulphuric acid, that are applied in the 

 manure pass through into the drainage water. 



A comparison of the drainage waters in winter 

 and spring shows that they are more concentrated 

 in the winter, because the manures (excepting the 

 nitrate of soda) have then been recently applied : the 

 chlorides wash out first, then the sulphates, and as 

 the season advances not only is the total amount of 



P 



