TllK ll.XIIKK OK llli; SOU, IVJ 



a gri-«»ater feeding- surface to roots, because the 

 particles of earth are very small (.')2). Koots 

 feed on the surfaces of hard particles of earth, 

 \\\u\ the feedin.u:-ai-»'a is tlu'rcfoic increased in 

 j)roj>ortion to the incrtMsc in the sui'face area 

 of tlif particles. I)ivi<linix a cui)e into two 

 • ••|ual jtarts increases its surface area l»y one- 

 tliii'd. (Dividing a cuhe ad<ls two sides or 

 surfari's.) Fining the s(>il may therefore he 

 equivalent to fertilizing it, so far as i>lant- 

 growth is conc»»rned. 



:;. //<)>(' (io))({ SfrurtKre is Secured 



.'>4. 'i'hc size of the soil particles, dctcrmin- 

 i!ig the texture of the soil, cannot he modified to 

 any api)reciable extent by ordinaiy farm practices. 

 Tillage has little effect in I'hanging tlu' size of 

 the ultimate parti<*les. 



55. The arrangement of the p;irti(^les, whirh 

 determines the structure, can he gitatly (•li;im:'d 

 hy farm practice. If th«» structure is lumpy and 

 open, tln< soil needs pulverization; if it is com- 

 j)act an<l hard, it needs loosening up. \'ery 

 loose and h»achy soils are usually improved if 

 the particles, j»articularly in the under soil, are 

 brouu'ht together and compacte«l. 



.')(). The size of the granules (or aggregations 

 "f particles) of soils is modified liy three general 



