Are, most Efficient Subsoilers. 85 



chicory, and think this is, as a rule, a sufficient quantity, 

 but that in dry lands 3 lbs., and perhaps even 4 lbs., may 

 be used with advantage.* 



Since writing the preceding remarks I have had 

 another visit from my friend. Dr. Voelcker, who in- 

 spected (September, 1897) the field, and at the close of 

 the most prolonged drought we have ever had. Part of 

 the field consists of strong clay, and my friend cut out 

 of this, with his pocket knife, several sections of soil, in 

 each of which was a chicory plant, and called my 

 attention to the fact that the soil was soft and friable, 

 having been kept in that condition by the powerful roots 

 of the plant, and also, no doubt, by the moisture it had 

 brought up from a depth in the land out of reach of the 

 effects of the drought. I am now so satisfied with the 

 results from deep-rooting plants that I am, as an 

 experiment, going to add a pound of parsnip seed per 

 acre to one of my next season's mixtures, in order to 

 deeply penetrate the soil, and increase in it the amount 

 of vegetable matter.! It should be considered, further, 

 in this connection that, by virtue of the acids in their 

 roots, plants have the power of making use of the 

 manurial matter contained in stones and gravel in the 

 land, and it has been found that if you bury in the soil 

 a block of polished marble, the roots of plants will 

 literally engrave the surface of the marble. One of my 

 numerous correspondents, who had read a letter of 

 mine in the Scotsman, wrote to me on the subject, and 

 headed his letter, " Out of these Stones Bread," and it 

 is literally true that plants can, in great measure, by 

 virtue of the acids in their roots, supply themselves with 



* Prom my experience this year (1907) I think that as much as 5 lbs. 

 of chicory may be used with advantage, as this quantity (which was sown 

 in the Front Field in 1906) does not interfere with other grasses either 

 above or below ground. 



t Parsnip seed was sown in the Outer Kaimrig field in 1899, but from 

 that experiment I have formed the opinion that chicory is superior to 

 parsnip as a deep-rooter. 



