CAMPBELL'S SOIL CULTURE MANUAL 95 



soil is moist, as all observing farmers know, the soil grains 

 more readily separate one from the other. The real or 

 desirable object of plowing is not simply to turn the soil 

 over, but in addition to turning the soil is the pulverizing 

 The more thoroughly this is done the better opportunity 

 the heat, air and moisture have to exercise their full power 

 to combine all the properties into plant foods so that they 

 may be available to the plant. 



So far as we can grasp the true principles regarding the 

 necessary physical conditions, they are found in recogniz- 

 ing the following facts, viz: 



First That fertility is not matter, or a substance, 

 or something that exists in the soil in given quantities 

 and makes plants grow if the seed is put in the soil, regard- 

 less of how it is tilled or fitted. 



Second That the growth of all plants dependsp uon 

 the quantity and force or energy of the available fertility, 

 and this is great or small just in proportion to the phys- 

 ical or mechanical condition of the soil. 



Third That the soil is nature's laboratory, where 

 the proportion of air and water may be combined in just 

 the proper quantities. If the soils are too coarse and lie 

 too loose, then there is too much air for the water the soil 

 can hold, and with the most ideal climatic conditions 

 only fairly good crops can possibly be grown. 



Fourth That water is a vital element in all vegetable 

 growth, but it is not the only element that the tiller of the 

 soil must see to. Air is equally important, and in all 

 tillage, air must be recognized and the soil prepared with 

 an eye to utilizing it just as nature demands. Give nature 

 a chance and she will do wonders, but don't expect too 

 much without some intelligent effort on your part. 



