356 relax:, ns of elements 



grown. I say partly, because I do not believe that the whole or 

 ganic matter necessarily enters into the constitution of the plants 

 which spring up during the rotation ; no doubt a considerable por- 

 tion of the manure is lost through spontaneous decomposition, or is 

 carried away by the rain ; and another portion may remain a long 

 time dormant in the soil, to act as a fertilizer at a more or less dis- 

 tant period ; just as in the present rotation the manure formerly in- 

 troduced co-operates with that recently added. One thing is certain, 

 viz., that the proportion of manure indicated is essential for a\erage 

 crops ; by diminishing it the produce is necessarily lessened. Last- 

 ly, it is proved that after the rotation the crops have consumed the 

 manure, and the earth will not yield its increase unless a fresh quan- 

 tity be added. 



I now proceed to consider the relation subsisting between the 

 quantity of organic matter buried in the soil as manure, and what is 

 recovered in the crops. In this way the respective proportions of 

 elementary matter which various crops derived from the air and the 

 soil, may be determined approximately, and a knowledge obtained 

 of those rotations which least exhaust the land, or in other words, 

 which obtain from the atmosphere the largest amount of organic 

 matter. 



The rotations set down in Tables I. and II. are those definitively 

 adopted at Bechelbronn, and throughout the greater part of Alsace. 

 These two rotations, which differ only in the hoed crop introduced, 

 potatoes in one, beet-root in the other, are almost identical ; nearly 

 the same quantity of dry matter being produced per acre, and nearly 

 the same quantity of organic material withdrawn from the atmo- 

 sphere. 



The rotation No. 3 was introduced by Schwertz at Hohenheim ; 

 theoretically, it is one of the most advantageous ; it was tried at 

 Bechelbronn but abandoned, because, from meteorological causes, 

 peas and vetches fail frequently. 



Table No. 4, shows the triennial rotation with manured fallow ; 

 this is disadvantageous in point of theory. The organic consti- 

 tuents of the crop exceed but little those of the manure. Suppos- 

 ing that even the whole of the straw were converted into manure, 

 the farmer would still be compelled to procure manure from abroad, 

 in compensation for the out-going of wheat. It is thus obvious why 

 triennial rotation always requires a great deal of meadow land. 



In table No. 5, the result of the continuous cultivation of Jerusa- 

 lem artichokes is given. At Bechelbronn these are dressed every 

 two years with about ten loads of dung per acre. Upon an average 

 20 tons of tubers and about 2 tons of woody stems are gathered in 

 the course of two years. It will be perceived from perusal of this 

 table, that the culture of Jerusalem artichokes presents, theoretical- 

 ly, considerable advantages. The organic matter of the crop greatly 

 exceeds that of the manure. Moreover, in Alsace, where it is very 

 common, it is held to be most productive. Still, the organic matter 

 of the stems must be taken into account, which, practically speak- 

 ing, are nearly worthless. 



