On Arjricultural Chemistry. 



by the side of these plots we also grow the crop both without ma- 

 nure of any kind and with farrn-yard-manure, we shall have ob- 

 tained in the comparative results a far more satisfactory solution 

 of the question as to what constituents were, in this ordinary 

 course of agriculture, most in defect in respect to the production 

 of the particular crop experimented upon, than any analysis of 

 the soil could have given us. In other words, we should have 

 before us very good ground for deciding to which of the con- 

 stituents of the farm-yard manure the increased produce was 

 mainly due on the plot provided with it, in the case of the par- 

 ticular crop : not so, however, unless the soil had been so far 

 exhausted by previous cropping as to be considered jwactically 

 unfit for the growth of that crop without manure. We lay parti- 

 cular stress on this exhaustion, because we believe that the vast 

 discrepancy in the comparative results, with different manures, 

 by different experimenters, arises more from irregularity in what 

 may be called the floating capital of the soil than from irregu- 

 larities in the original character of the soil itself, or from any 

 other cause, unless we include the frequent faulty methods of 

 application. 



It is, then, by this synthetic rather than by the analytic me- 

 thod that we have sought our results ; and in the carrying out of 

 our object we have taken Wheat as the type of the cereal crops, 

 Turnii^s as the type of the root crops, and Beans as the representa- 

 tive ot the Leguminous corn crop, since these most frequently 

 enter into rotation ; and having selected for each of these a field 

 which, agriculturally considered, was exhausted, we have grown 

 the same description of crop upon the same land, year after year, 

 with different chemical manures, and in each case with one plot or 

 more continuously unmanured, and one supplied every year with 

 a fair quantity of farm-yard-manure. 



In this way 14 acres have been devoted to the continuous 

 growth of Wheat since 1843, 8 acres to the continuous growth of 

 Turnips from the same date, and 5 to 6 acres to that of Leguminous 

 corn crops since 1847. Besides these we have made other field 

 experiments — amounting in each year to from 30 to 40 on wheat, 

 upwards of 90 on turnips, and 20 to 30 on beans — and also 

 some on the growth of Clover, and some in relation to the che- 

 mical circumstances inv{)lved in an actual course of rotation, 

 comprising Turnips, Barley, Clover, and Wheat, grown in the 

 order in which they are here stated. 



It may be stated, too, that in addition to these experiments on 

 wheat and the other crops usually grown upon the farm as above 

 referred to, we have for several years been much occupied also 

 with the subject of the feeding of animals — viz. Bullocks. Sheep, 

 and Pigs — as well as in investigating the functional actions of the 



