106 PLANT LIFE ON THE FARM. 



confirm Boussingault's assertion* that alkaline or earthy 

 salts, although indispensable to plants, nevertheless, exer- 

 cise no action unless combined with matters capable of 

 furnishing nitrogen. 



Superphosphate of lime only. The scanty and stemmy 

 produce on the plot, to which this substance is applied, 

 has been but little greater than that on the unmanured 

 plots. The grasses and miscellaneous plants have been 

 slightly increased, the Leguminosse diminished. There 

 has been a great admixture of species, but little luxuriance 

 of any. Holcus lanatus, Avena flavescens, Poa trivialis, 

 Lolium perenne, and Festuca ovina have been among the 

 most prominent grasses, while the freer-growing Dactylis 

 does not apparently find so much subsistence as it requires. 

 Lathyrus pratensis among the leguminous plants, and 

 Rumex Acetosa and Achillea Millefolium among the weeds, 

 have been slightly benefited, others yielding even less than 

 without manure. Boussingault's observations, already 

 quoted under the head of mineral manures, apply equally 

 here. The great French chemist found, as in the Kotham- 

 sted experiments, that superphosphate, uncombined with 

 substances capable of yielding ammonia, produced little 

 or no effect on vegetation. Boehm's experiments, however, 

 go to show that young plants raised in distilled water, 

 die before the nutritious matter stored up in the seed, 

 or in the seed-leaves is exhausted, but if lime be added, 

 especially in the form of ulmate, before this point is reached, 

 the seedlings resume their healthy appearance, the develop- 

 ment of the radicle according to Deherain being particularly 

 favoured by this substance. (See p. 14.) 



* Boussingault, Ann. Soc. Nat. 1857, Bot. 19. 



