434 



(5) Corn is able to draw upon the permanent water in tlie j^ronntl, when it lies at a 

 depth at least as j^reat as 7^ feet, in the case of a subsoil of rather coarse sand. 



(6) Corn may reduce the per ceut of water in a subsoil of sand to 7 per cent of the 

 dry soil at a depth of 40 inches below the surface, and when the water table is but 42 

 inches, still lower. 



The capacity of soil to store water. — The fact universally observed that during seasons 

 of drought vegetation suffers from lack of moisture, even when the water table lies 

 within 5 feet of the surface, proves conclusively that the rate at which capillary 

 actiou can carry water toward the surface is not great enough at all times to meet 

 the demands of cultivated crops, and this being true it is important to know, first, 

 the capacity of the upper 5 to 7 feet of soil to store water; and, second, the per cent 

 of this stored water different varieties of cultivated plants can profitably use ; for 

 these facts stand in the same relation to plant feeding that a knowledge of the 

 amount of hay and grain stored in the barn does to stock feeding. 



To ascertain how great the storage capacity of undisturbed soil may be, five tin 

 cylinders, each 1 foot in length and 6 inches in diameter, were filled with soil in its 

 natural condition by forcing them into the ground one above the other. 



From this investigation, details of which are given, it appears that 

 the uijper 5 feet of soil were able to store 21.24 inches ot water, or three 

 fifths of the total annual rainfall in this locality. Experiments with 

 reference to the rate of drying and to the amount of water which these 

 soils would hold when saturated are reported. From the latter it 

 api)ears that the soil under experiment, when thoroughly filled with 

 water, as might be the case after heavy rains, might contain 24.48 

 inches of water to each square foot of surface, or more than two thirds 

 the average annual rain- fall. 



Rate and extent of capiUary movement of water in soil in its natural condition. — It 

 appears to be generally conceded that capillary action is an important factor in lifting 

 the ground water toward or to the surface, where jdants can avail themselves of it 

 and of the minerals it may hold in solution. How rapid this movement may be in 

 soils of different kinds and depths, as they exist undisturbed except by the processes 

 of tillage, is a question having many important practical bearings; and yet our 

 specific and positive knowledge on this subject is very limited indeed. The fact that 

 vegetation, during seasons of drought, suffers for lack of moisture, even where per- 

 manent water exists in the ground within a few feet of the surface, is conclusive 

 evidence that the normal rate of capillary movement is not very great. * * * 



[This is illustrated] by the following observations: On May 13, while corn ground 

 recently planted contained 23.33 pounds of water to the 100 pounds of dry soil, in the 

 surface 6 inches, clover growing not 2 rods distant in the same kind of soil, had drank 

 the water so much faster than capillary action could bring it that there remained but 

 8.59 pounds to the 100 pounds of dry soil. » * * 



These facts illustrate in a very forcible manner the great power vegetation has 

 of withdrawing water irom the soil, and how naked tillage conserves it, while at 

 the same time they furnish the strongest possible argument against allowing even a 

 single weed to grow in a field where other crops are expected. 



To study the rate at which water may rise in diflerent kinds of soil in their natural 

 conditions, the cylinders above described were placed with their feet resting in water 

 1 inch deep after the soil had been dried, and the rate at which the water rose in them 

 noted by daily weighings. * * » The rate at which the several samples of soil 

 became saturated with water is shown in a table. [It appears that the soil in the cyl- 

 inder was not saturated with water at the end of 36 days.] The per cent of water 

 in soil on which corn had been grown was determined down to a depth of 3 feet on 

 October 23, and again on December 13, standing water in the ground at the time being 

 7.5 feet below the surface. • » * 



