MANURES. 157 



crop cannot be grown on land destitue of these ingre- 

 dients. But such land, by the addition of plaster, 



which is composed of sulphuric acid and lime, will 



produce clover abundantly. 



293. Some have supposed, that, if we could ascertain 

 precisely the wants of our crops, the labor of apply- 

 ing heavy, bulky manures might be avoided ; that by 

 spreading on our fields a few pounds of some mineral, 

 we might carry off as many cart-loads of produce, and 

 continue to do so, without further trouble. But such 

 a course would soon exhaust the soil of its organic 

 matter. The truth is, as confirmed by both science 

 and experience, that if we would take off great crops, 

 we must put on great quantities of manure. The 

 ploughing in of green crops will do something towards 

 keeping the land up ; and the application of compara- 

 tively light, but expensive fertilizers, from abroad, 

 may do something. 



HOME RESOURCES FOR MANURES. 



294. But after all, the farmer's great resource must 

 be at home. The farm micst he made to enrich itself 

 mainly. Every particle of manure, made by the ex- 

 penditure of crops, must be husbanded with the ut- 

 most care. Many a farmer, who has expended 50 tons 

 of hay, and considerable grain crops, has heretofore 

 had but 100 loads of manure, and that, too often, de- 

 prived by rains and evaporation of its best qualities ; 

 whereas he ought to have had four or five times as 

 much, and of a better quality. I am aware that this 



