ROTATION OF CROPS. 225 



and ingeniously defended by the powerful name of Decandolle, 

 and which the closest scrutiny of scientific observers since, 

 has pronounced unworthy of credit, does not form a fifth 

 reason for rotation. It is because principles essential to suc- 

 cessful vegetation have been abstracted, not that others hurt- 

 ful to it have been added by preceding crops, that rotation is 

 ivndrivd necessary. From all that has hitherto been learned 

 on the subject of rotation, either from science or practice, two 

 general principles may be assumed as proper to guide every 

 farmer in his course of cropping. First to cultivate as great 

 a variety of plants as his soil, circumstances and market will 

 justify ; and second, to have the same or any similar species 

 follow each other at intervals as remote as may be consistent 

 with his interests. From the foregoing observations on the 

 subject, it is evident that the proper system of rotation for 

 any farmer to adopt, must depend on all the conditions by 

 which he is surrounded, and that it should vary according to 

 these varying circumstances. 



It is a practice with some to alternate wheat and clover, 

 giving only one year to the former and one or two years to 

 the latter. This will answer for a long time on soils adapted 

 to each crop, provided there be added to the clover, such ma- 

 nures as contribute to its own growth, and such also as are ex- 

 hausted by wheat. The saline manures, ashes, lime, &c. may 

 be added directly to the wheat without injury ; but gypsum 

 should be sown upon the clover, as its benefits are scarcely 

 perceptible on wheat, while upon clover, they are of the 

 greatest utility. But there are objections even to this, as it 

 does not allow an economical or advantageous use of barn- 

 yard manures, which, from their combining all the elements of 

 fertility, are the most certain in their general effect. In dif- 

 ferent countries of Europe, fields which have been used for 

 an oft-recurring clover crop, have become clover sick, as it is 

 familiarly termed. The plant will not grow luxuriantly; 

 sometimes refusing to vegetate, or if it starts upon its vege- 

 table existence, it does so apparently with the greatest re- 

 luctance and suffering, and ekes out a puny, thriftless career, 

 unattended with a single advantage to its owner. This is sim- 

 ply the result of the exhaustion of one or more of the indis- 

 pensable elements of the plant. If it be desirable to pur- 

 sue this two-course system for any length of time, noth- 

 ing short of the application of all such inorganic mat- 

 ters as are taken up by the crops, will sustain the land in 

 a fertile condition. We subjoin simply for the purpose of 

 I* 



