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Vol. XVIII, Second Series. 



ROCHESTER, N. Y., MAY, 1857. 



No. 5. 



lEOTATION OF CEOPS. 



That there is no absolute necessity for rotation of 

 crops in all cases, is abundantly proved. Indian corn 

 has been grown on many of the rich bottoms of the 

 West, year after year, for half a century. Onions 

 are grown every year on the same land, with mani- 

 fest advantage. On the Rotharastead experimental 

 fields, wheat has been grown on the same land for 

 fourteen successive years, and in 1855 the yield on 

 one of the plots was firty-five bushels per acre. Tur- 

 nips have been grown annually on the same land for 

 fourteen years. Beans, peas, tares and potatoes are 

 also grown on the same land each year, without any 

 ill eflects being observed. 



The advanioge of rotation cannot be doubted, 

 and many theories have been propounded to account 

 for it. Decandolle thought that plants excreted 

 matter from their roots, which was injurious to plants 

 of the same species and beneficial to some others of 

 a dilFereut species. This may be true in regard to 

 some plants, but the facts we have alluded to above 

 prove that it is not true of all ; and we may safely 

 conclude that nearly all our commonly cultivated ag- 

 ricultural plants do not excrete matter at all injurious 

 to the same plants when sown the following year on 

 the same eoil. However great the advantages there- 

 fore, there is no necessity for rotation of crops. 



All agricultural plants require the same food, with 

 this difference: that one needs more of this or that 

 particular element than another. For instance, tur- 

 nips require more phosphoric acid than wheat, 

 wheat more ammonia than turnips, beans and clover 

 more potash than either of the former, &c. It is 

 easy to see that these crops can be alternated with 

 each other to advantage; that the soil which does 

 not contain sufScient phosphoric acid for a good 

 crop of turnips may contain enough for a large crop 

 or wheat, and that the soil which lacks sufficient 

 ammonia for the production of a maximum croji of 

 wheat may yet have enough for a maximum crop of 

 turnips. 



Barn-yard manure contains all the elements of 

 plants. We may, therefore, by its use in sufficient 

 quantity, grow the same crop, on a soil having the 

 requisite meclianical conditions, every year. But it 

 is evident that this would entail a loss of some of 

 the elements of manure. For instance, if we add 

 sufSeient barn-yard manure to a soil to furnish the 

 requisite quantity of ammonia for the growth of a 

 large crop of wheat every year, we provide in this 

 manner much more carbon and more phosphoric 



acid than the wheat requires. If, on the other hand, 

 we add enough barn-yard manure to a soil to furnish 

 the required amount of phosphoric acid for the 

 growth of a large crop of turnips every year, we 

 add more ammonia than is necessary. But if, instead 

 of growing wheat after wheat, we grow turnips, or 

 some other similar crop, the excess of carbon and 

 phosphoric acid provided in the barn-yard manure 

 for the wheat crop is taken up by the turnip plants, 

 which, as we have said, require more of these sub- 

 stances than wheat. On the other hand, if we grow 

 wheat after turnips, instead of turnips after turnips, 

 the excess of ammonia which it was necessary to add 

 to the soil in the barn-yard manure in order to sup- 

 ply sufficient phosphoric acid for the turnip crop, 

 will be just the very thing required for the wheat. 



The same remarks hold good where little or no 

 barn-yard manure is used. The soil contains all the 

 elements of plants — if it did not, no agricultural 

 plant would grow — but this food is held in an insolu- 

 ble condition, and we have to till the land and ex- 

 pose it to the influence of the atmosphere in order 

 to render this insoluble matter available for plants. 

 Now if, by summer fallowing, we render enough of 

 this plant-food soluble to furnish the wheat plant 

 suiScient ammonia for the growth of a good crop, it 

 is quite probable that we render more phosphoric 

 acid soluble than the wheat requires. And hence, 

 if we were to follow up the system of summer fal- 

 lowing for wheat, without taking any intermediate 

 crop, we should lose more or less of this valuable 

 fertilizer. But if we should grow an intermediate 

 crop of clover or turnips, this phosphoric acid would 

 not only be saved, but prove very beneficial to either 

 of these crops — especially the latter. 



There are scarcely any two plants that require the 

 elements of their food in precisely the same propor- 

 tion; and hence, by substituting some other of the 

 fourteen elements of which all plants are composed 

 for the ones we have instanced, the above remarks 

 will hold true for nearly every crop we cultivate. It 

 is easy to see, therefore, that, at present a judi- 

 cious system of rotation lies at the very foundation 

 of all good practical agriculture, though, when we 

 have learned from carefully conducted scientific field 

 experiments what are the exact requirements of our 

 difjerent crops, we may be able to dispense with it 

 by supplying the particular manure M'hich the plant ^ 

 requires. This, according to Liebig, is the "single ' 

 problem worthy of scientific agriculture at the pres- 

 ent time;" and he justly remarks: "How simple a 

 form would the labors of the farmer assume, could 



