Conserving Soil Moisture. 191 



cultivation after the corn is in tassel or the vines Ix-iiin t<> 

 well cover the ground. 



222. Depth of Cultivation to Save Moisture. In regard 

 to this point it must be kept in mind that the soils out of 

 which mulches are made are the richest on the farm and that 

 when they are converted into perfect mulches they are prac- 

 tically useless so far as direct plr.nt feeding is concerned. 

 The general rule must then be to make the mulch just 

 as thin as it can be and not permit too heavy a waste of 

 the deeper soil water. 



On the lighter and coarser grained soils the mulches 

 may be shallower than on those of the clayey type. 



In Wisconsin we have found that with the ordinary 

 narrow pointed tooth cultivators a depth of about three 

 inches saves more moisture and permits larger yields of 

 corn in about 15 cases out of 20 than less depth of culti- 

 vation. Where the tool is of such a character that it 

 shaves off the whole surface of the ground and leaves the 

 stirred soil spread in a blanket of uniform thickness the 

 stirring may be shallower than if the surface of the ground 

 is left in either narrow or wide ridges. 



223. Depth and Frequency of Cultivation Should Vary 

 With the Season and Crop. From what has been said in the 

 preceding paragraphs it follows that the soil may to ad^ 

 vantage be cultivated more deeply and more frequently 

 during the early part of the season when the soil tem- 

 peratures tend to be low, when the moisture may be over- 

 abundant, and when weed seeds are. germinating. Later 

 in the season, however, when there is not as great need 

 to encourage the development of nitrates by tillage, when 

 the roots have come closer to the surface, and the main- 

 tenance of a soil mulch is the chief or only object, the 

 cultivation may evidently be less deep and not so fre- 

 quent The general practice then should be to gradually 

 make the cultivation both less deep and less frequent. It 

 should also be kept in mind that cultivation may gener- 



