OP AGRICULTURE. 27 



tences. 'The space in depth to which the roots of 

 crops penetrate, and from which they derive their 

 food is usually limited by the depth to which the plow 

 has run. Beneath that point, especially in clay soils, 

 the roots make, none or but little progress, The un- 

 broken subsoil which is compound of clay, is not easily 

 penetrated by rains. Hence, after the plowed masa 

 becomes saturated, the surplus water escapes over 

 the surface, carrying off the most valuable portions 

 of the soil, and leaving unsightly gullies behind. 

 Deep plowing tends to prevent washing, 



A deeply broken soil is a storehouse for moisture, keep- 

 ing moisture in reserve for seasons of drought. When 

 the sun, the air and the growing crops have taken up 

 the surface moisture, some of the roots are still deep 

 down in the earth, where the supply is abundant. In 

 a deep broken soil a great deal of moisture rises to 

 the surface by capillary attraction, it brings with it 

 elements of fertility in solution, and as the evapora- 

 tion at the surface goes 011 these are left to aid in en- 

 riching the surface soil. A drought may thus improve 

 land which has been properly plowed. 



The subsoil plow is designed to follow the ordinary 

 surface plow in the furrow left by the litter, By 

 this means the bottom of the furrow is broken and 

 pulverized, without being turned up. The surface plow 

 then throws its next furrow upon this loosened por- 

 tion of the subsoil, and so the process is continued 

 until the whole field is broken to the depth of from 

 twelve to fourteen inches. 



There are various kinds of subsoil plows used, all 

 of which do good work. A common snakehead coul* 

 ter (so called at the South) extending fifteen inches 



