98 BOARD OF AGRICULTURE. 



Question. Might it not be owing to an absorption of the 

 root into the top ? 



Prop. Johnson. It may be. I had supposed that old roots 

 would have the greater absolute weight. If these figures 

 are correct, they are interpreted by your suggestion, which is 

 supported by some observations that have been made regard- 

 ing the mode of growth of the underground organs. 



In the next column of figures we have the ratio of root to 

 top. Tlie root is taken as a fixed quantity, ten. In the case 

 of rye we have, in the first place, 10:17 ; then 10:45, 10:59, 

 10:186. In the case of clover, 10:16, 10:19, 10:23, and 

 lastly 10:15, which may be an error of observation. 



Here you have another capital fact brought out — the 

 greater relative quantity of roots in the ripe clover plant. 

 You have half as much roots as top, in the clover plant, 

 whereas you have almost fourteen times as much top as roots 

 in the ripe rye plant. These plants, then, are very different 

 in the way in which they act upon the soil, and therefore in 

 the way in which they leave the soil. When you reap rye close 

 to the ground you take away one hundred and thirty-six out of 

 one hundred and forty six pounds, and tlms leave very little in 

 the soil. When you cut clover you may leave half as much in 

 the ground as you take off. That is a point of great impor-. 

 tance in considering their relative bearing upon the question 

 of exha:ustion, and shows that you may expect a very dif- 

 erent result from leaving clover roots and clover stubble in 

 the soil than from the roots and stubble of rye. 



Mr. Lyman. If we cut the rye low we take very nearly 

 tlie whole of the plant off from the land, and it requires five 

 times as much put back to bring the rye field up to an equal- 

 ity with the clover field, as it stands cut, with the roots in the 

 ground. Therefore we cannot look for a crop that would be 

 equal to what clover would bring us unless we restore this 

 ratio. 



Prof. Johnson. You are right. 



Mr. Lyman. What is the difference if we plow the two 

 crops under ? 



Prof. Johnson. The total weight of your rye crop is 272 ; 



