no The Great World's Farm 



Feldspar is that one of the three minerals of which granite 

 is composed, which, when finely powdered and washed 

 away, forms beds of clay. In this case it was first only 

 coarsely powdered, and the barley grew to a height of 

 fifteen inches; moreover, the ears formed, one ear ripened, 

 and two seeds were perfected. In the second instance the 

 feldspar was finely powdered, and the stalks were very 

 much stronger. One grew to a height of twenty inches, 

 and perfected four seeds. 



Feldspar alone, though a compound of several elements, 

 could not in any case produce a good crop; for the stiffest 

 clay soils under cultivation have been not only well ground, 

 whether by ice or water, but also mixed besides, and con- 

 tain sand and other ingredients. 



It is, of course, possible for the soil particles to be too 

 fine, as they are in pure clay, which is so close in texture 

 as to exclude what is as necessary to the plant as food 

 and water, namely, air. A plant's roots need air as much 

 as any other part of it, for they are constantly taking up 

 oxygen, and hence all specially fertile soils contain a large 

 proportion of sand, which makes them light and porous; 

 for though fine, it is not nearly as fine as the particles 

 composing the clay, and does not turn into a stiff paste 

 when mixed with water. 



In a stiff, heavy soil roots make their way with less 

 ease and with less rapidity than in a light, loamy one con- 

 taining a large proportion of sand, and therefore they 

 must needs collect food less rapidly. Moreover, both air 

 and water penetrate a heavy soil less easily than they do 

 a light one, and hence not only is the air which the roots 

 need less able to reach them, but less water can enter 

 also, and consequently less soil is dissolved and made ready 



