446 MASSACHUSETTS AGRICULTURE. 



exhausted by crops and requires to be replenished bj returning 

 to the soil the ingredients which may have been removed. 



You ask what use can be made of these principles discovered 

 by science ? In reply, I would say, that they are the founda- 

 tion of rules like the following : — 



1. If there are undecomposed vegetable or animal sub- 

 stances in the soil, expose them sufficiently to the air by plough- 

 ing or otherwise ; or 



2. Mix with the soil alkalies or manures that will hasten 

 the decay of these subtances, in order that they may be reduced 

 to that form of matter which will nourish veiz-etation. 



3. Stir the mould as frequently as possible while the crop 

 is growing, in order that the air may come in contact with 

 decayed vegetable and animal matter for the production of car- 

 bonic acid to nourish the plants. 



4. Adapt the manure which you put upon the soil to the 

 particular kind of crop which you intend to raise. Thus a few 

 pounds of bone manure might, in a given case, by furnishing 

 phosphate of lime, be of more service for a crop of wheat, than 

 any quantity of other manure which does not contain that 

 ingredient. 



5. When you find that a particular kind of manure has lost 

 the power which it once had in recruiting the soil, do not 

 attempt to make up in quantity what it has lost in power, but 

 rather try some other kind of manure. 



6. In forming beds of manure, bring together substances 

 that are so related to each other that their chemical constitu- 

 ents will, in union, form the appropriate food for the particular 

 crop which you wish to raise. 



But besides the study of the original soil, and of mould on 

 the surface, it is of great importance to the young farmer to 

 study the laws of the plants which he raises, as they are devel- 

 oped in the science of vegetable physiology. 



The great object of agriculture is to produce, in the most 

 advantageous way, certain qualities, or a maximum size of cer- 

 tain organs or parts of particular plants. Now this object can 

 be obtained only by supplying the condition necessary to their 

 production. In wheat, we want the greatest size, number and 

 excellence of the seed ; in the potato, of the root. We cultivate 



