THE CULTURE OF FARM CROPS. 



CHAPTEK XLIII. 

 THE ROTATION OF CROPS. 



It is not impossible to grow the same crop year after year, 

 upon the same land successfully. Permanent meadows are 

 instances of this kind of continuous culture. But it is nec- 

 essary to fertilize the soil in such a way as to restore pre- 

 cisely what the crops have withdrawn from it. This con- 

 tinuous culture however is not practicable in ordinary 

 farming, although it has been shown by Sir J. B. Lawes on 

 his experimental farm at Rothamstead in England, that 

 forty continuous crops of wheat, barley, or roots, can be 

 grown in as many years, by the use of suitable manures or 

 fertilizers and without any diminution in the yield. 



In ordinary farming it has been found that when the 

 same crop is grown consecutively for a number of years 

 upon the same land, the product gradually decreases until 

 it no longer pays the farmer for his labor. But he finds 

 that although one crop, such as wheat, begins to fail the 

 second or third year, some other crop, as corn, potatoes, tur- 

 nips, clover, or grass, will thrive; and that a succession of 

 these may be grown in a number of years without any de- 

 terioration. And not only is this found to be the case in 

 regard to farm crops, but we find it to be the case in the 

 natural growth of the land; for when a forest of hard woods 

 is cut down, and the land is left to grow up with trees again, 

 the new growth consists of evergreens; and on the other 

 hand when a pine forest is cut down, oaks, poplars, and other 

 deciduous trees take the place of it. The reason for this 

 change of product is not difficult to perceive. When we' 

 consider the nature of each growth we see that each kind 

 differs remarkably. For instance, in the following table 

 we give the analyses of leaves, wood, and bark, of the 

 two kinds of trees which thus follow each other; and it is 

 easy to see v/hy one kind follows the other and not its 

 own kind. 



