LESSONS FROM EXPERIENCE 301 



between the time of the germination of the weed seeds 

 and the time when the season is sufficiently advanced to 

 plant the crop. This period should be utilized as far as 

 possible for the destruction of weeds before the crop is 

 planted. Much labor in keeping the crop free from 

 weeds during its growing period can thus be saved. 



Harrov/ing small grain for the destruction of weeds 

 after the grain is sown and until it has reached a height 

 of 3 or 4 inches may sometimes be practised to advantage. 

 Experimental evidence does not show it to be generally 

 profitable. Harrowing corn and potatoes after planting 

 and until the young plants have attained a height of 2 

 or 3 inches is quite generally practised to advantage. 



It is absolutely essential for the most profitable growth 

 of com, potatoes, the sorghums, and, in fact, all the inter- 

 tilled crops, that sufficient tillage be given to keep the 

 growing crop free from weeds until the plants have at- 

 tained such growth that they will be seriously injured by 

 the cultivators or the horses. (Bui. 268 — p. 24-25). 



247. The Application of the Capillary Theory to Dry 

 Fanning Practices. — The capillary theory is undoubtedly 

 responsible for more false reasoning about dry l&nd agri- 

 culture than any other one thing. It is a convenient 

 theory to explain certain well-known phenomena such as 

 the rise of oil in a lamp wick, but it must be taken in its 

 entirety. It will not do to eliminate the one most import- 

 ant factor in the theory and then expect it to work. This 

 one factor is the presence of a constantly replenished sup- 

 ply of free-moving vmter at the base of the system. In 

 other words, a permanent water table within a few feet 

 of the surface of the soil, a condition that is never met 

 under true dry land conditions. Therefore, any system 

 of dry land farm) practice that is dependent upon the as- 



