THK MOISTfKK IS THK SOIL 



n:^ 



plants nre enabled early in their growih to semi their roots down, 

 and wlun drought comes they are not seriously injured. Figs. 

 15 IS illustrate this. 



7y<i. The soil resorvoir may be understood by likening it to 

 a pan. A two-ineh rainfall fills an inch-deep pan and runs it 

 over ; but if the depth is inereased to two inches, none of the 

 rain escapes. The hard-pan or water-table is the bottom of thu 

 soil reservoir. If this bottom is within a few inches of the sur- 

 face, the ordinary rainfalls fill the soil so full that it is muddy, 

 and some of the water may be lost by surface washing. Deep 

 plowing lowers the bottom of the reservoir, an<l the soil holds 

 more water and yet remains ilrier. 



81(1. Tillage operations should vary acconling to the nature 

 of the soil. Those soils which- are loose and porous should be 

 compacted after plowing, so that the capillary connection may 

 Ikj ri'Stored between the surface and the subsoil. The roller 

 may be usetl. With finely divided soils, which have a tendency 

 to become t«M) compact, only so much tillage should bo given as 

 is necessar)' to produce the proper degree of pulverization. It is 

 possible to so compact and fine some soils, as clays, that the 

 spaces between the soil particles is filled, and a condition is 

 pro<luced which prevents the rise of moisture by capillarity, an<l 

 also prevents the absorption of rainfall and the passage of air. 



B\h. Of general farm crops, a)>oiit three himdred pounds of 

 water is used in the production of one pound of dry matter .\n 

 inch of rainfall weighs, approxim.itely, one htmdred and thirteen 

 and one-half tons to the acre. The student will discover that 

 the rainfall of the growing months may not bo sufficient to supply 

 the crop ; hence the necessity of saving the rainfall of winter 

 and spring. 



83a. On the general subject of soil moisture and its conser- 

 Tation, read Chaps, v. and vi. in Kintr's "Soil." and Phnp. iv. in 

 U-.l/erft' "Fertility of the Land." Also consult publications of 

 the Ktperimeiit Stations and l'. S. I)epnrtmeiit of .Airriculture; 

 anil part 3 in Vol. [ of ('v.-iopedia of .Vmerican Agriculture ; also 

 the recent loil books of Ililirnr-l. nml of Lvon ami Fiiit«iii. 



