66 Botation of Or ops. [February, 



injurious to the growth of that same grain, or vegetable, the succeeding 

 year ; and the injurious tendency must be cumulative by every repeated 

 succession of the same kind of crop. By a suitable rotation, those excre- 

 mentitious particles, which have been deleterious to one tribe of plants, 

 furnish nutriment to another ; hence different kinds of crops succeed one 

 another with advantage. And it becomes a nice point to ascertain the 

 order best calculated to follow each other. As a general rule, culmife- 

 rous crops, ripening their seeds, should not be repeated without the 

 intervention of roots, herbage, or fallow. There is here a wide field open 

 to experiment, in which little has been, as yet, effected. We mention one 

 fact corroborating the above theory of fetal exudation. The lean grows 

 pretty well in pure water. It was found, on trial, that the water con- 

 tinued clear, but assumed a yellow tint. Chemical tests and evaporation 

 seeraed to detect a matter similar to gum, and a little chalk. Another 

 bean was placed in this liquor and would not thrive. Then, in order to 

 determine whether this was occasioned by the want of carljonic acid, or 

 by the presence of some exuded matter, plants of wheat were placed in 

 the water. They lived well, the yellow color of the fluid became less 

 intense, the residuum less considerable, and it was evident that the new 

 plants absorbed a portion of the fecal matter discharged by the first. 

 Hence, the practice in Europe, of cropping wheat after beans, is justified 

 by this experiment. It is now everywhere regarded as fully established, 

 that alternate husbandry, especially where the several processes of labor 

 which belong to each crop, are properly executed, will not only preserve a 

 soil from exhaustion, but by the introduction of a small amount of putres- 

 cent matter, will yearly improve in fertility. And whether the cause be 

 as above, or found in the nature of the soil, or of the plants themselves, 

 experience has established the fact, beyond controversy, that a soil will 

 hold out much longer where an appropriate succession is observed, than 

 where it is not. The frequent repetition of the same kind of crop, even 

 at short intervals, is also to be reprobated for the same reason. 



It may not be amiss to give hero a few examples of what have been 

 found by experiment successful rotations. Let the basis of these rota- 

 tions be a summer fallow : then, 



FIRST ROUND OF ROTATION. 



Rotation for Loams and Clays. 



1. Fallow. 4. Oats. 7. Potatoes, or Corn. 



2. Wheat. 5. Clover. 8. Wheat ; when it should 



3. Corn. 6. Wheat. be laid down in grass. 



