492 Agricultural Experiment Station, Ithaca, N. Y. 



and removed by the drains in its downward course, but the drain- 

 age flow begins only when, by the accumulation of the rainfall 

 the level of the free water has been brought up to the level of the 

 drain. Thus the reservoir for the supply of capillary water is 

 kept nearer the surface during a drought and is removed a proper 

 distance from the surface during a wet time to insure a healthy 

 and proper development of the roots of plants. 



Mineral substances as conservers of moisture. — Among the ma- 

 terials of commerce which are applied to soils as indirect ferti- 

 lizers, are lime, gypsum and salt, all of which are thought to act 

 as conservers of soil moisture. The application of quick lime 

 to certain soils has been found to have a most beneficial action. 

 When used upon a heavy clay it causes a certain adhesion or 



146. — The flocculation of the surface of clay 147. — The action of lime, at a few inches 

 soils by the addition of quick lime. iu depth, in sandy soil. 



flocculation, a binding together of the minute particles, and pre- 

 vents their running, at time of rains, into a compact, hard crust 

 (Fig. 146). It causes a more granular condition, making the soil 

 looser and more porous, allowing the water of rainfall to per- 

 meate it more readily. As a result of flocculation, the pores 

 of the soil near the surface are enlarged, and it thus better serves 

 the purpose of a mulch to hold in reserve the moisture under- 

 neath. 



On sandy soils the difficulty in conserving moisture arises from 

 the fact that they are so open and porous that the water passes 

 through and is lost to the plant. It would seem that an applica- 

 tion of lime here would tend to aggravate the difficulty. On 

 clay, the action of the lime takes place at or near the surface, 

 the soil being so compact that it is not washed down through 

 the soil. In sand, the pores are so large that the lime sinks read- 

 ily into the soil, and instead of finding the effects of its appli- 



