50 On the Rain and Drainage - Waters at Rothamsted. 
any of the plots which had not received ammonium-salts since 
the preceding spring ; but it has been explained (p, 47) that 
all the estimates of loss for this period are probably too high. 
After this great loss during the winter, there was very little 
further loss from Plot 15 during the succeeding period of growth. 
But again receiving the ammonium-salts in October 1880, there 
was, from the date of the preceding harvest to the commencement 
of active growth in the following spring, a loss of 57"2 lbs. 
estimated to be due to the manure, or nearly sixteen times as 
much as from the spring-sown Plot 7 during the same period. 
We turn now to the comparison of the results on Plots 7 
and 9. Plot 7 received annually a given amount of nitrogen as 
ammonium-salts, and Plot 9 approximately the same amount as 
nitrate of sodium. Plot 7 received also the complete mixed 
mineral manure ; but only one half, or one land, of Plot 9 (9a) 
received the mineral manure, the other half (9i) receiving the 
nitrate of sodium alone. On both plots the nitrogenous manure 
was applied in the spring. 
During the very wet period from spring sowing to harvest 
1879, there was an estimated loss from the ammonium-salts of 
16'75 lbs. of nitrogen per acre, but from the nitrate of sodium 
of 43'43 lbs. There was little or no estimated loss from the 
manure of either plot from harvest to the next spring sowing. 
From spring sowing to harvest (1880), with very little drainage, 
there was a loss of 3"55 lbs. from the ammonium-salts, and of 
14-29 lbs. from the nitrate ; and during the very wet period 
from harvest to the next spring sowing (1881), there was a loss 
of 3"65 lbs. from the ammonium-salts, and of 23*26 lbs. from 
the nitrate of sodium ; or, over the whole twelve months, ot 
7*2 lbs. from the ammonium-salts, and of 37*55 lbs. from the 
nitrate. 
There was thus a very much greater loss of nitrogen bv 
drainage when a given amount was supplied as nitrate of sodium 
than when as ammonium-salts. But the loss from the nitrate 
was probably much greater than it would have been in conse- 
quence of one of the two lands receiving no mineral manure, 
and the growth on it being accordingly very much less. Still, 
the loss will generally be greater from a given amount of nitrate 
than from a corresponding quantity of ammonium-salts, when 
the amount of nitrogen supplied is much in excess of that which 
can be taken up by the crop, or when the season is wet. 
Table LI. shows for the two seasons, the average annual 
quantities, in lbs., of nitrogen supplied in manure, obtained in 
the crops, estimated in the drainage, and in the crop and 
drainage together ; also the amounts unaccounted for in either 
crop or drainage. 
