SOIL FERTILITY 



with the ends of the chimneys resting in water, 

 allowing the water to creep up through the dry 

 soils. Notice how long it will take water to creep 

 up through six inches of good soil; how long to 

 pass down through it. 



The modification of the porous quality of soils 

 is accomplished by the same means used in chang- 

 ing clay to sandy soils or the reverse. The capil- 

 larity of soils is modified by these same changes 

 which make the soils more close or open, as may 

 be required. But in the best of soils, capillarity 

 has to be checked so as to keep down near the 

 roots the ground moisture and to prevent its rise 

 to the surface and its escape by evaporation. The 

 simplest means is by dry farming; that is, by a 

 dust mulch or dust blanket which is a covering 

 of loose, fine earth from two to three inches deep 

 over the whole surface of cultivated plots. It 

 should be frequently renewed over small areas by 

 the hand plough, or by the use of hoe and rake, 

 or by the cultivating stick, and always as soon 

 after rain or even heavy dew as the ground is 

 workable.* "In general, soil should not contain 

 more than 60 per cent of its water-holding capacity; 

 /. e. at least two-fifths of the spaces should be 

 occupied by air." 



Where natural manure cannot be obtained, 

 resort must be had to commercial fertilizers. 

 Sometimes, however, street sweepings may be 



♦ Over large tracts of land by the horse or steam plow set to the 

 required depth with care to avoid cutting roots. 



99 



