Effect of Increasing the Ammonia of the Manure. 165 



The addition of silicates during the last fourteen years of 

 the twenty has further increased the amounts of hay yielded, 

 and of nitrogen and mineral matter taken up. 



TABLE XXXIX. AVERAGE PER ACRE PER ANNUM, BY 800LB. (OR 

 400LB.) OF AMMONIA-SALTS, AND MIXED MINERAL MANURE, WITH- 



OUT, AND WITH, THE ADDITION OF SILICATES ; PLOTS lla. AND 116. 



Average per Acre per Annum. 



* 4001b. only in 1859, 1860, and 1861. 



It is remarkable that, with the enormous amount of about 

 2001b. of ammonia, corresponding to about 1641b. of nitrogen, 

 applied per acre per annum, for so many years, there 

 appeared to be as large, if not a larger, proportion of the 

 nitrogen supplied taken up by the growing herbage, as where 

 only half the quantity was employed. There was, in fact, a 

 proportionally much greater increase in the assimilation of 



