Ixx 



KOYAL HORTICTJLTUEAL SOCIETY. 



one plant dominates over another in mixed herbage, under the in- 

 fluence of different man ares," &c. 



This subject, having excited considerable interest and discus- 

 sion, was referred to the Chemical Sub-Committee, with the re- 

 quest to report whether the Sub- Committee deem it desirable to 

 recommend experiments to be tried as likely to throw further 

 light on various questions relating to vegetable growth and the 

 specific action of certain fertilizing elements, such as potash, phos- 

 phate of lime, nitrogenous matters, &c. 



It will be remembered that Dr e Grilbert, at the June Meeting, 

 referred to some very striking experiments conducted for many 

 years at Rothamstead Park by Mr. Lawes and himself on per- 

 manent pasture, which has been under grass probably for cen- 

 turies. 



Under ordinary management this herbage yielded about fifty 

 species of graminaceous, leguminous, and other plants usually 

 found in permanent meadows. 



The number of species of plants was but little changed on those 

 experimental plots in the park to which a complex but purely 

 mineral manure was applied, consisting of salts of potash, soda, 

 magnesia, and sulphate and phosphate of lime. 



On the other hand, salts of ammonia, nitrate of soda, applied 

 by themselves, or the addition of nitrogenous manures to mineral 

 fertilizing matters, greatly diminished the number of species in the 

 herbage. 



According to the particular kind of nitrogenous manure used, 

 and the quantity and combination with other fertilizing matters 

 in which nitrogenous manures were employed, the diminution in 

 the number of species varied ; but in all cases it was strikingly 

 apparent, and in some instances amounted to about one-half of 

 the species in the herbage from the unmanured part of the park, 

 or those dressed with purely mineral manures. 



Attention was further directed to the fact that not only the 

 w r eight of the produce reaped per acre was much influenced by the 

 description of the manures -which were put on the different expe- 

 rimental plats, but that likewise the relative proportions of grami- 

 naceous and of leguminous and miscellaneous plants in the produce 

 were found to vary considerably with the manures employed. 



Thus, to cite only a few examples, the weight of the gramina- 

 ceous plants in the produce from the unmanured plats, and 

 those dressed with purely mineral manures, in round numbers 



