PROFESSOR J. J. MAPES'S ADDRESS. 603 



will restore them to their original hardness in a single year, 

 but in properly prepared soils the effects are very different. In 

 such soils as are properly prepared for the subsoil plough the 

 disintegration causes all the inorganic constituents of plants 

 contained in them to be rendered available for the use of crops. 

 First, the atmosphere carries them through the necessary chem- 

 ical changes and renders them soluble in water ; next, in such 

 solution they pass into the roots of plants, which are sure to 

 enter a well divided subsoil, and in this condition they are 

 carried to the surface. The roots of crops left in the ground, 

 by their decay, deposit this accumulated material drawn from 

 the subsoil in the surface soil, in a state ready to perform all 

 necessarily required of it. 



During seasons of drought the roots of plants pass down 

 into these subsoil cuts and receive moisture ; and during ex- 

 cessive rains the excess of water can pass from the surface into 

 the subsoil, leaving part of the roots at least not drowned out, 

 and it is for these reasons that corn on subsoiled land never 

 shows curl in the leaf, and partly for these reasons that sub- 

 soiled meadows seldom run out. Another and more important 

 reason for this latter fact is that when the roots of grasses 

 reach a cold, un disintegrated subsoil, the root crown ceases to 

 tiller, and no side roots are projected for the formation of new 

 plants, whereas in subsoiled land, the roots may travel to a 

 much greater depth before any such result can take place. 

 Grain crops, when grown on subsoiled lands, tiller freely, and 

 hence thin sowing of seed on such soils is a good practice. In 

 wheat growing districts the saving of seed amounts to a profit. 



Underdraining, when properly pursued, is still more impor- 

 tant. Millions of acres of valueless lands have been restored 

 by this practice, and pent up quantities of materials of which 

 plants are formed, have been rendered available to the farmer • 

 nor must it be conceived that underdraining is useful in 

 swampy lands alone. The very hill-tops may sometimes be 

 improved by thorough underdraining. The admission of at- 

 mosphere through these drains permits its heat, which always 

 rises, to find its way from the underdrains through the whole 

 depth of soil above it ; for heat, although difficult to descend, 

 rises with ease, and a properly constructed underdrain is never 

 without a current of air, and that portion entering during the 

 day time from the influence of the sun previously exerted 



