138 Practical Farming 



in water, from one third of i per cent, to i per cent, 

 was dissolved in the water. This means that if there was 

 an acre a foot deep of this finely pulverized material, 

 10,000 pounds of plant food otherwise unavailable would 

 become soluble in a week. 



What this would mean can be better understood when 

 we reflect that in applying fifteen tons of stable manure 

 to an acre we furnish only 150 pounds of potash and 140 

 pounds of phosphoric acid. The more we grind the soil, 

 then, the more it will yield up to us its store of plant food. 



Water passes more readily from a coarse to a fine layer 

 of soil. Hence, there is an added advantage in the fining 

 of the surface soil, while allowing the deeply broken soil 

 below to remain undisturbed to bring up moisture from 

 below to keep the supply good near the surface. 



To sum up then: pulverization of the soil not only 

 favors the root development and the penetration of the 

 air into the soil, but it improves the moisture and other 

 physical conditions, promotes weathering and disintegra- 

 tion, and thus releases plant food, and also suppHes 

 favorable conditions for the growth of the nitrifying 

 organisms for which oxygen is needed, and discourages 

 the growth of the denitrifying organisms which do not 

 thrive in presence of oxygen. 



Weed destruction, or what is better, weed 

 Weed prevention, is rather an incident in tillage 



MtrlTln'' ^^^^ ^^ ^^J^^^- Proper tillage, sufliciently 

 Incident of frequent, will certainly prevent the growth 

 Tillage of weeds. Weed-killing should never have 



to be done in a cultivated crop. The pri- 

 mary object of tillage is to produce the conditions in the 



