FARMER'S ASSISTANT. 109 



the putrid matter ,will grow much faster than those at a 

 distance ; because those nearest have a greater chance of 

 absorbing the impure air emited from it, than those growing 

 farther off, 



See further, AIR. 



From the earth, plants derive some of their component 

 parts, as discovered by chemical analysis ; such as earths, 

 salts, oil, Sec. and from water, whether mixed with the 

 earth, or otherwise, they imbibe the juices or sap, which is 

 so essential to their existence. 

 See SAP. 



Some manures, it would seem, operate by attracting 

 matter which is food for plants ; such as gypsum, which is 

 supposed to attract nitre and moisture. Ashes afford salts 

 and attract nitre. Other manures again afford, in part, 

 the food of plants, and at the same time assist them in ob- 

 taining more from the earth, by opening it for the more 

 easy extension of their roots; such as barn- dung and ma- 

 nures of that kind. Others, perhaps, assist directly in sup- 

 plying food ; such as salts, blood, putrid flesh, &c. Others, 

 again, merely serve to open earths which are too solid to 

 admit the roots in search of food ; such as sand, roten wood, 

 sawdust, Sec. applied to clays. And, lastly, clay applied to 

 sand assists, in part, by supplying additional food, and partly 

 by enabling the soil to retain a sufficiency of water to sup- 

 ply plants with the requisite proportion of this article. 



Some plants extract their food principally from the air; 

 some, mostly from air and water; and others, principally 

 from the earth. The hyacinth, and many other plants, will 

 grow well with air and water, without the assistance of 

 earth. But, generally speaking, plants require the united 

 assistance of air, water, and earth; and from these they 

 extract that food which is requisite to bring them to per- 

 fection. 



Some plants acquire most of one kind of food from the 

 earth, and some another. Tap rooted plants, again, derive 

 their nourishment from a greater depth ; while those with 

 fibrous roots merely extract from the surface. Hence, the 

 earth, as the common parent of plants, may become ex- 

 hausted, in continually producing some kinds; while it may 

 stiil be well fited for the production of others; and hence, 

 in some instances, arises the necessity of a change of crops. 

 See CHANGE OF CROPS. 



FOREST. Every farm ought to have a piece of wood- 

 land, or forest, sufficient for fuel and other purposes. 

 Raising timber, for the purpose of fencing, will not often 

 be found advisable. Farmers must eventually depend on 

 jnaking stone walls, or hedges, for the purpose of enclosing 



