C 317 3 



surface were first ploughed in. Carbonic acid gas 

 is formed during the whole time by the action of the 

 vegetable matter upon the oxygene of the air, and the 

 greater part of it is lost to the soil in which it Was 

 formed, and dissipated in the atmosphere. 



The action of the sun upon the surface of the 

 soil tends to disengage the gaseous and the volatile 

 fluid matters that it contains ; and heat increases the 

 rapidity of fermentation : and in the summer fallow, 

 nourishment is rapidly produced, at a time when no 

 vegetables are present capable of absorbing it. 



Land when it is not employed in preparing food 

 for animals, should be applied 'to the purpose of the 

 preparation of manure for plants ; and this is effected 

 by means of green crops, in consequence of the ab- 

 sorption of carbonaceous matter in the carbonic acid 

 of the atmosphere. In a summer's fallow a period is 

 always lost in which vegetables may be raised, either 

 as food for animals, or as nourishment for the next 

 crop ; and the texture of the soil is not so much im- 

 proved by its exposure as in winter, when the expan- 

 sive powers of ice, the gradual dissolution of snows, 

 and the alternations from wet to dry, tend to pulverize 

 it, and to mix its different parts together. 



In the drill husbandry the land is preserved 

 clean by the extirpation of the weeds by hand, and by 

 raising the crops in rows, which renders the destruc- 

 tion of the weeds much more easy. Manure is sup- 

 plied either by the green crops themselves, or from 

 the dung of the cattle fed upon them ; and the plants 

 having large systems of leaves, are made to alternate 

 with those bearing grain. 



