THE GREENWOOD TKEE. 149 



simpler language of everyday life called ashes. It is 

 mainly the first of these three, support, that the farmer 

 thinks of when he calculates crops and acreage ; for the 

 second, he depends upon, rainfall or irrigation ; but the 

 third, manure, he can supply artificially ; and as 

 manure makes a great deal of incidental difference to 

 some of his crops, especially corn which requires 

 abundant phosphates he is apt to over-estimate vastly 

 its importance from a theoretical point of view. 



Besides, look at it in another light. Over large areas 

 together, the conditions of air, climate, and rainfall are 

 practically identical. But soil differs greatly from place 

 to place. Here it's black ; there it's yellow ; here it's 

 rich loam ; there it's boggy mould or sandy gravel. And 

 some soils are better adapted .to growing certain plants 

 than others. Rich lowlands and oolites suit the cereals ; 

 red marl produces wonderful grazing grass ; bare up- 

 lands are best for gorse and heather. Hence everything 

 favours for the practical man the mistaken idea that 

 plants and trees grow mainly out of the soil. His own 

 eyes tell him so; he sees them growing, he sees the 

 visible result undeniable before his face ; while the real 

 act of feeding off the carbon in the air is wholly 

 unknown to him, being realizable only by the aid of 

 the microscope, aided by the most delicate and difficult 

 chemical analysis. 



Nevertheless French chemists have amply proved by 

 actual experiment that plants can grow and produce 

 excellent results without any aid from the soil at all. 

 You have only to suspend the seeds freely in the air by 

 a string, and supply the rootlets of the sprouting 



