VERMONT AGRICULTURAL REPORT. 41 



for immediate and effective service. Water which is thus vapor- 

 ized from the surface of the soil serves no purpose in agriculture 

 save that of cooling it — sometimes an advantage but more often 

 not — unless perchance there is an excess of water. The process 

 is a natural one and its result inevitable. Neither process nor 

 result can be abrogated ; nor would it be desirable to stop their 

 action if it could be done. It is the means whereby the plant roots 

 gain sustenance for plant growth. It is the vaporization which 

 is undesirable ; and this, tillage may retard. It cannot prevent it ; 

 no means thus far devised can do this ; but its extent can be les- 

 sened. Tillage retards the evaporation of soil moisture by the 

 severance of the connection of the irregular and tortuous capillary 

 tubes with the surface, by breaking and by clogging them. The 

 widening of the upper portions of the tubes serves to lessen the 

 Tieight through which the water may be raised, while the clogging 

 stops the water at a point just below the obstruction. Just as the 

 San Francisco water supply was cut off by the breaking and 

 clogging of the water mains in April's earthquake, so are the 

 smaller water pipes of the soil broken when it is disturbed by 

 tillage. And, furthermore, just as the water supply was reestab- 

 lished when the broken conduits were repaired, so is the connec- 

 tion with the soil surface again restored naturally and soil moist- 

 ure escapes again, unless recourse is had to frequent stirring of 

 the soil. According, however, to the frequency of the surface 

 cultivation during the earlier months of the crop growing season 

 is the extent of moisture conservation. An infrequent cultiva- 

 tion retards moisture escape for the time being, but the readjust- 

 ment of the surface soil particles naturally occurring results in a 

 reestablishment of the connection of the surface tubes with those 

 below, a repairing process as it were, and the former condition is 

 renewed. In the absence of irrigation and if timely rains do not 

 occur, the only chance for a maximum crop lies in keeping at it 

 throughout the earlier part of the growing season. 



Taking up now the specific tillage operations in the rela- 

 tionship to moisture conservation. 



PLOWING. 



The three furrow slices that are in common use are the flat, 

 the overlapping and the rolling. The first of these completely 

 inverts the sod, laying it flat in the bottom of the neighboring 

 furrow. It completely severs the connection of the capillary tubes 

 and is an effective method, viewed solely from the standpoint of 

 soil moisture retention, though open to serious objection in other 

 respects. The second system contemplates the production of a 

 lapping furrow slice which carries a ridged and broken surface, 



