0*N THE FOOD OF PLANTS. ]g 



in excellent manure. In some parts of Wales they have agree with ex- 

 scarcely any other dressing for their wheat. I well remem- P en « Ilce - 

 ber, that in the parish of Lansamlet, in Glamorganshire, 

 my father, who was very attentive to agriculture, put most 

 of his stable dung on meadow land, and used only lime for 

 wheat. He had two lime-kilns constantly burning for his 

 own use, and with this manure he obtained the most abun- 

 dant crops; but then his land was principally a dark vege- 

 table mould, and much of it was peat, which before it was 

 drained had been a bog. On this land I have counted 

 sixty grains to an ear, not picked and culled out of many 

 others as being longer than the rest, but taken by handfuls 

 at random. 



In his land, lime as a dressing was particularly apt, be- Attempt tor,*. 

 cause, as we know, it hastens the putrefactive process, and coucllc l "« m » 

 promotes the dissolution of vegetable substances, convert- 

 ing them quickly into vegetable mould. 



Now in my experiments there was no vegetable matter 

 to be dissolved, and therefore no benefit according to chy- 

 mical principles was to be expected from the lime. The 

 trial was however made, and the received opinion as to 

 the effect of lime is thus far confirmed. 



But in my experiments the lime appeal's to have been Injurious by> 

 deleterious. This was not from its causticity, for the plants f° r "j>nsacru<t 

 lived ; but from its action as a cement in forming a crust 

 on the surface of the pots impervious to air. For in these 

 pots I remarked, that after rain the water stagnated, and 

 did not readily penetrate as in the other pots. 



Free access of air to the roots of plants seems to be of vast Access of air 

 importance, and almost essential to their growth. With re- to roots a™* 

 gard to seeds, access of air is absolutely needful to their ve- sary# 

 getation. Hence it is that charlock (sinapis arvensisj 

 will remain in the earth for centuries, if deposited below the 

 vegetating distance, as we have occasion to observe on Salis- 

 bury-plain, where no charlock is ever seen, unless when 



the downs are broken up. The land is then covered with c a 



r oeed vege- 



it ; but till then the seeds remain as in vacuo, and are there- tating 

 fore not liable to change. 



This deposit of seed must have happened in most remote a f ter having 

 antiquity, either when the hill country, like the low lands, lain in the 



formed 



