154 MISSOURI AGRICULTURAL REPORT. 



very fundamental and important truth. Imagine a cube of granite one 

 square foot on each face. If this cube were lowered into water and 

 raised from it again it would come out overspread with a sheet of water 

 measuring 6 square feet in area, for the cube has 6 faces. Let this 

 surface be dusted over with finely ground stable manure, well charged 

 with the soil organisms which bring about its decay. A spear of corn 

 planted at the center of the top face of this cube would find itself in 

 possession of a pasture area measuring six square feet, over which its 

 roots could place themselves to imbibe moisture and the food materials 

 with which it becomes charged as solution of rock and decay of or- 

 ganic matter takes place. Now imagine the cube quartered. The area 

 of the surface of granite, of the sheet of water, of the pasture, is 

 doubled, for there are now 4 cubes each with an area of 3 square feet 

 and with no more soil, the corn roots have a pasture of 12 square feet. 

 There are 12 square feet upon which solution may take place, to which 

 water may adhere, where organic matter may decay where the roots 

 may feed. If now each of these cubes is quartered, their surfaces will 

 again be doubled, and we shall have a cubic foot of soil, whose aggre- 

 gate surface measures 24 square feet. Make the cubes one-hundredth 

 of a foot on an edge, and the total surface becomes 600 square feet. 

 If again the cubic foot of granite is divided into cubes one thousand of 

 which together measure an inch, the separate pieces may be readily seen 

 singly with the unaided eye, and it would be so coarse that we would 

 call it a fine sand, and yet the total surface to which water could ad- 

 here, upon which chemical action and solution could take place, and 

 against which the root hairs could place themselves to feed, would be 

 6,000 square feet, or one-seventh of an acre per cubic foot. 



On this chart there has been represented, all on the same scale, 

 circles having the effective diameters of three soils, the finest clay, the 

 average loam and the coarse sandy type. In the finest clay type it re- 

 quires 6,000 of them set in line and in contact to measure an inch ; in 

 the loam type, 1,200; and in the coarse sandy soil, 200. Of tlie parti- 

 cles of the finest clay soil 30 are required to span the diameter of a sin- 

 gle grain of the coarse sandy type, and five of them are needed to 

 measure one of the mellow loamy soils. From our illustration of the 

 cube of granite you will readily see that the finest clay soils possess 30 

 times the internal surface, to which water may adhere, upon which 

 soluble and dissolved phmt foiul materials may be formed and stored, 

 and where soil organisms and ihc roots of plants may feed, that which 

 is possessed by soils of the coarse sandy types, and five times that pos- 

 sessed by the loams. 



So great is the internal surface of soils that its extent must be ex- 



