14G On the Composition of Waters of Land-Drainaf/e. 



of ammonia-salts alone, contained much less solid matter per 

 <2:allon than that from the adjoining^ plots, which received saline 

 mineral inanures in addition to the ammoniacal dressing. 



2. The drainage from all the Plots contained less solid matter 

 than the samples collected in December of the preceding year. 

 This appears to indicate that at a period of the year when vege- 

 tation makes a vigorous start, the scduble saline soil constituents 

 are taken up In' the plant and utilized in promoting its groAvth ; 

 whilst at a time of the year when vegetr^tion is at a standstill 

 the soluble constituents pass more copiously into the drains. 



o. With the exception of the drainage from Plot 1), where 

 nitrate of soda was used, all the other samples collected in May, 

 1867, contained only minute quantities of nitric acid, whilst all 

 the samples collected in December of the preceding year con- 

 tained more nitric acid, and some of them in considerable 

 quantity. 



It would appear, therefore, that during the active growth of 

 Avheat, nitric acid, which is applied to the land in the shape 

 of nitrate of soda, or which is gradually produced by oxydation 

 of ammoniacal top-dressings, is consumed by the wheat-crop in 

 considerable quantities, and employed, together with the needful 

 soluljle mineral constituents of the soil, in the development of 

 the plant. 



4. In the December drainage-waters, the proportion of nitric 

 acid was largest in the samples from those plots upon which the 

 largest quantities of ammonia-salts were used, whilst the drainage 

 from Plot 9, dressed in spring with 550 lbs. of nitrate of soda, 

 contained scarcely more nitric acid than that from the unmanured 

 portions of the same field. In the drainage from Plot 9 collected 

 in May, on the other hand, the amount of nitric acid was con- 

 siderable, being from 10 to 15 times as great as that in the 

 drainage from most of the Plots manured with ammonia-salts. 



On Plot 9 it thus appears that there was more nitrate of soda 

 at the command of the crop than it could utilize, and con- 

 sequently an appreciable quantity passed into the drains ; whilst 

 in the case of the plots dressed with ammonia-salts not much 

 more nitric acid was produced at the time by oxydation from 

 the ammonia-salts than could be at once consumed and utilized 

 by the growing crop. 



The differences in the relative proportions of nitric acid in 

 the December and the iVIay drainages, from the plots manured 

 with nitrate of soda and ammonia-salts respectively, are very 

 instructive, and full of practical interest. The small quantities 

 of nitric acid, or rather nitrates, in the drainage from land 

 highly manured in spring with ammonia-salts, and the much 

 larger amount in the drainage from land top-dressed with nitrate 



