148 •' Scientific Intelligence. [Makch, 



All these different changes and alterations suggested by experience, in the 

 succession of crops, and the soils which are best suited to them, produce this irre- 

 vocable result : — that a particular corn crop shall succeed a particular green crop, 

 on the soil that is best adapted to them ; and that manure shall be applied, at 

 given intervals, with one of the green crops, or with bare fallow. Thus, on 

 strong soils, wheat must follow a manured fallow, grass after wheat, oats after the 

 grass, then beans after oats, and wheat to precede the manured fallow after the 

 beans. On weak soils, barley succeeds to turnips which have been manured, 

 grass follows the barley, and oats precede the manured turnips. 



Experience having proved that these successions of corn and green crops, on 

 their respective soils, are best suited to insure the greatest produce, it is requisite 

 that one series of successions shall follow another, in regular order, on its respec- 

 tive soil. These series of successions are called the " Rotation of crops." Should 

 any alteration be desired in the rotation, it can only consist of a substitution of 

 one corn crop for another, or one green crop for another ; for the corn and 

 green crops must always stand in the same relative position to each other. 

 But this substitution of one crop for another will generally be attended with a 

 sensible deterioration in the crop or soil, if the deterioration be not counteracted by 

 an additional quantity of manure. A modification may be effected in the rotation 

 by extending the time which it occupies. Thus the rotation on strong soils, which 

 embraces six years, may be extended to seven or eight ; and that of four years, 

 on weak soils, may be extended to five or six years. The extension of the length 

 of the rotation must be effected alone through the gentle, or the green, and not 

 the severe or corn class of crops ; and that not by means of any of the green crops 

 indiscriminately. Thus the extension must not be effected by a repetition of any 

 of the corn crops ; for, we have already observed, such a proceeding would has- 

 ten their own deterioration ; nor by adding an alternate green and corn crop to the 

 end of the rotation, for that would be a mere attempt to deteriorate the soil bv 

 delaying the application of manure ; nor by repeating the turnip or potatoe crop 

 for neither can be raised without manure ; — but it must be effected by allowing the 

 grass to remain as many years longer as it is desired to extend the term of the 

 rotation. The period of grass crop can alone be extended without trouble. 



Experience again steps forward to check speculation in the endurance of the 

 grass crop. On strong soils it is inimical to the grass crop to prolong its exist- 

 ence beyond one year, and hence annual grasses and the six years' rotation is best 

 suited to that class of soils ; whereas, an extension of the existence of grass on 

 the weaker soils, serves to strengthen the energy of the soil. Two at least or 

 perhaps three years of grass confers a lasting benefit on such soils. Having 

 thus fixed upon the length of rotation which is best adapted to the soil, let it be 

 irrevocably adhered to. 



In the establishing of this beneficial system of cropping, experience alone 

 has discovered the progressive steps which have led to its completion. The ra- 

 tionale of the system has never been inquired into by those who have administered 

 its rules or benefited by their application. The investigation of causes is the duty 

 of the philosopher, and not of the farmer, who has ODly to deal with effects • but 

 the happiest results may be anticipated from the combined efforts of both ; when 

 the former directs his mind to establish the principles upon which the experienc- 

 ed operations of the latter depend. 



Among all the important practices in husbandry, that of the rotation of crops is 

 the most important ; for by an attentive adherence to it, the utmost regularity of 



