444 MASSACHUSETTS AGRICULTURE. 



consequence was, that much of this land had to lie unimproved 

 in the state of old field, as it is there called, until the potash 

 is restored by a further decomposition. 



I have called your attention to a single constituent, namely, 

 potash, because it is so well known. What is true of this, is 

 likewise true of other ingredients of the soil which were 

 originally imparted to some rocks in larger measure than to 

 others, but which by continued cropping, are liable to be ex- 

 hausted. 



Here, then, we have certain great principles of the science 

 of agriculture, in this brief statement, and you ask me what 

 practical use can be made of these principles^ or in other words, 

 what rules can be deduced from them to be applied to the art of 

 farming ? 



In reply, I would say, that from these principles we deduce 

 rules for your guidance, like the following: — 



1. Raise that kind of crop, the mineral ingredients of which 

 are found in the original soil, as for instance, raise wheat on 

 soil that originally contained potash and the phosphate of lime 

 or magnesia. 



2. When a soil has lost, by cultivation, the quality of fertility 

 which it once had, let it lie fallow with the expectation that it 

 will, by the decomposition of the fragments of rock in the soil, 

 recover its fertility. 



3. In a case like the last, you may plough deep in order to 

 bring up to the air fresh portions of soil which have not thus 

 been exhausted. Thus the edges of the dirt thrown out from 

 a ditch, often show more fertility than the field generally. 



4. When a field has lost its power of producing one kind of 

 crop, try another kind which does not demand largely that 

 particular element in the soil which is exhausted. Thus, a soil 

 that has been exhausted by raising tobacco, may produce a 

 large crop of beans, which does not require potash to be in 

 the soil. 



5. Or, to generalize the last rule, adopt a rotation of crops. 



6. In your endeavors to recruit the soil, be careful to ascer- 

 tain the particular ingredient in which it is deficient, and then 

 supply that ingredient. 



Thus far, I have called your attention to the original mineral 



