110 Bulletin 174. 



that well-drained soil will not withstand a drought as well as an 

 iindrained soil. The contrary is true. Every one who has tilled 

 the soil is familiar witli })]aees that are wettest in a wet time and 

 dryest in a dry time. When these places dry at all, they dry like a 

 brick. A wet soil can never be tilled so as to present the greatest 

 amount of surface for film moisture and give it a mellow texture to 

 receive a gentle saturation of air ; and standing water robs it of 

 much heat required by the soil and plants. 



20. Di'ainage mnakes a soil reservoir. — There is a place in every 

 soil at which the free water stands. This place is called the water- 

 table. It may be three inches down, or a hundred feet. It is the 

 bottom of the soil reservoir, the bottom of our dish-pan. This dish- 

 pan, or the upper and tillable soil, is the reservoir. It is the part in 

 which the water is held as films on the soil particles. These films 

 travel from particle to particle, the general tendency being upward 

 because the moisture is passing off near the top of the soil by means 

 of evaporation and appropriation by plants. Moisture is constantly 

 supplied from the water-table below. We speak of this movement 

 as capillary attraction. 



Under-drainage lowers the water-table. It lowers the bottom of 

 the dish-pan ; and thereby there is a deeper reservoir above it for 

 the holding of film moisture and the distribution of roots. 



But, the reader says, if the water-table supplies moisture to the 

 upper soil, then it must be useful and necessary. Certainly ; but it 

 must not be too high, for roots of farm plants do not thrive in stand- 

 ing water. If the upper soil is well tilled, capillary attraction will 

 bring the moisture up. 



21. Do not let the inoisture get away.- — We want this film moist- 

 ure in the upper soil in order that roots may use it. The plants do 

 not use it, to any extent, after it has passed off into the atmosphere. 

 Therefore, stop this water before it reaches the atmosphere. 



How ? Put a layer of loose dry earth between the moist soil and 

 the atmosphere. This layer will stop the upward capillary flow. 

 Tins layer is the earth-mulch. It conserves, or saves, moisture. 



22. Dry and hard soils may he benefited hy under-drainage. — 

 The water-table is lowered. Air is admitted. The soil does not 

 puddle. It becomes fine. Under-drainage makes wet soils dry by 



