CULTIVATION AFTER PLANTING 31 



capillarity shows that in tubes of that diameter water 

 will rise from seven to eight yards. . . . This upward 

 movement of the lower moisture, though sometimes 

 injurious owing to the accumulation of saline substances, 

 may in a great many cases be beneficial, provided it be 

 stopped before it comes into contact with the surface air. 

 This is what is done by the surface mulching, which for 

 the small pores of the soil substitutes pores of large 

 dimensions through which capillary ascent is insignificant. 

 This mulch acts as a surface covering. The soil should 

 be cultivated after every rain that has been heavy enough 

 to puddle the surface. This cultivation should be re- 

 sorted to as soon as the implements can be passed over 

 the ground without clogging. If the ground has become 

 so dry that rain falling on it goes only to increase the 

 water film round the soil particles, and does not start a 

 downward percolation, capillary ascent of soil moisture 

 from the lower layers is so certain that soon after such 

 rain the deeper soil has become measurably drier than it 

 was before, while the surface foot is found to contain more 

 water than had fallen upon it. This will in most cases be 

 an advantage, provided surface evaporation be checked 

 as soon as possible." 



" A leading question * in connexion with cultivation is 

 the depth to which the soil should be stirred for the best 

 results. Many of the early students of the subject found 

 that a soil mulch only one half inch in depth was effective 

 in retaining a large part of the soil moisture which non- 

 cultivated soils would lose by evaporation. ... In 

 general, however, the deeper the cultivation, the more 

 effective it is in reducing evaporation. Fortier, in the 

 experiments in California, showed the greater value of 

 deep cultivation. During a period of fifteen days, begin- 

 ning immediately after an irrigation, the soil which had not 

 been mulched lost by evaporation nearly one-fourth of the 

 total amount of water that had been added. A mulch 

 four inches deep saved about 72 per cent, of the e vapor a - 

 * " Dry-Farming/ 5 By J. A. Widstoe. 1912. 



