ROTATION OF CROPS. 



fore thoy have matured their seeds, ! 

 exhaust the soil less tlian when they 

 reiiKiin until they have ripened their 

 seeds. Thus the turnip, when used 

 in its green slate, is one of the least 

 exliHusting in the agricultural class 

 of plants to which it belongs ; but the 

 turnip, when allowed to remain upon 

 the ground until it has ripened its 

 seeds, is one of the most exhausting 

 plants that is cultivated among us; 

 and so it is with the rape and others. 



" Farther, certain plants, by the 

 larger or smaller quantity of manure 

 which the consumption of them afford, 

 are more or less usclul in maintaining 

 the fertility of the farm. 



" Wlien an herbaceous plant is suf- 

 fered to mature its seeds, and when 

 any part of these seeds is carried off 

 the farm, tiie plant affords, when con- 

 sumed by animals, a smaller return 

 of manure to the farm than if the 

 same plant had been cut down before 

 it had matured its seeds, and been 

 in that state consumed by animals. 

 Thus it is with the turnip plant re- 

 ferred to. This plant is, with us, 

 sown before midsummer. In the first 

 season it forms a napiform root, and 

 puts forth a large system of leaves. I 

 Early in the following season it puts I 

 forth a long stem, which bears flow- ; 

 ers, and the seeds are generally ma- 

 tured about midsummer. If this 

 plant is removed in the first stage of 

 its growth, that is, after it has put 

 forth its large leaves and formed its 

 bulb, and is then consumed by ani- 

 mals, it returns a great quantity of 

 manure ; but if it remains until the 

 second state of its growth, then the 

 consumption of its stems and leaves 

 return scarce any manure. The 

 juices of the root have apparently 

 been exhausted in affording nutrition 

 to the flower stem, the flowers, and 

 seeds. 



" It is beyond a question, that, in 

 order to bring a plant to its entire 

 maturity by the perfecting of its seeds, 

 a larger quantity of the nutritive mat- 

 ter of the soil is sucked up by it than 

 when it is brought only to its less 

 advanced stages. When crops of 

 plants, therefore, are suffered to ar- 

 670 



rive at maturity, they are greatly 

 more exhausters of the soil on which 

 they grow than when they are cut 

 down while they arc green ; and if 

 those seeds are in whole or in part 

 carried off the farm, the crops are ex- 

 hausters of the farm, as well as of 

 the ground which had produced them. 

 Were the ripened seeds to be wholly 

 returned to the soil, it may be be- 

 lieved that they might give back to it 

 all the nutritive matter which had 

 been derived from it. But, in prac- 

 tice, seeds are employed for many 

 purposes, and are generally carried 

 off the farm which produces them. 

 When this is done in whole or in part, 

 the plants produced are in an eminent 

 degree exhausters of the farm, as well 

 as of the soil on which they have 

 grown. 



" Farther, certain plants, from their 

 mode of growth and cultivation, are 

 more favotirable to the growth of 

 weeds than other plants. '^I'he cereal 

 grasses, from growing closely togeth- 

 er, and not admitting, or admitting 

 partially, the eradication of weeds, 

 are more favourable to the growth 

 and multiplication of weeds than such 

 plants as the turnip and the potato, 

 which are grown at a considerable 

 distance from each other and admit 

 of tillage during their growth, and 

 whose broad system of leaves tend 

 to repress the growth of stranger 

 plants. 



" Having these principles in view, 

 certain rules may be deduced from 

 them for the order in which the crops 

 of plants in cultivation in a country 

 shall succeed to each other on the 

 same ground. 



" 1st. Crops consisting of plants of 

 the same or similar species shall not 

 follow in succession, but shall return 

 at as distant intervals as the case 

 will allow. 



" 2d. Crops consisting of plants 

 whose mode of growth or cultivation 

 tends to the production of weeds, 

 shall not follow in succession. 



" '3d. Crops whose culture admits 



of the destruction of weeds shall be 



! cultivated when we cultivate plants 



j which favour the production of weeds. 



