DURATION OF ORGANIC MANURES. 215 



then the soil would be rich. But in neither case would there be 

 power in the soil to combine with an additional supply of aliment- 

 ary manure ; and if such were applied, it would be exhausted and 

 pass away, rapidly on the bad soil, and more slowly on the good ; 

 but certainly, in the end, on both. 



Again, suppose the soils to be more or less exhausted by scourg- 

 ing cultivation. Then their actual amount of alimentary matter 

 would have been reduced below what their respective shares of 

 lime could combine with and retain, under a state of nature, or of 

 mild tillage. Then, if alimentary manures were applied, so much 

 as was required for combination by the lime present would be as 

 permanently fixed as if the original fertility had never been ab- 

 stracted ; and any additional quantity and excess of manure, not 

 being so combined and fixed, would be totally lost in more or less 

 time, as in the previously supposed case. 



Lest these propositions may not appear, because of their novelty, 

 perfectly clear and unquestionable to every reader, an illustration 

 will be offered which can scarcely fail to induce their general and 

 ready admission. Suppose a cultivator to have two fields, one of 

 bad and poor soil naturally, and the other of the best natural qua- 

 lity and both having been brought under cultivation together, 

 and kept under the same rotation of crops and other management. 

 Suppose further that the equal and uniform course of cropping 

 has been such (whether taking one or two or three grain crops to 

 one year-of rest, and resuscitation), that both fields have neither 

 been reduced nor increased in average product, since brought under 

 regular tillage j and that such average product, when of corn, is 

 equal to 10 bushels per acre on the poor, and 50 bushels on the 

 rich soil. Now, these different products are derived from the dif- 

 ferent funds of alimentary and putrescent manure originally sup- 

 plied to the soil by nature, (whiclj were just so much as the lime 

 of each soil could combine with) ; and, under the supposed degrees 

 of exaction and relief, counteracting each other under tillage, the 

 same rates of product may be obtained for ever. And the yielding 

 of 50 bushels by the one soil operates no more to reduce its after- 

 power of production, then the yield of the other of but one-fifth of 

 that amount of crop. The yield from each soil, at and for the time, 

 is certainly so much reduction of its productive power ; but the re- 

 cuperative power of each (to seize upon and retain new supplies for 

 fertilization, drawn from the atmosphere, and from the grass and 

 weeds grown and suffered to decay on the land,) is in proportion 

 to the yield ; and the vegetable growth serving for manure, and 

 atmospherical influences, during a year of rest, will continually 

 give to the good soil the renewed power of producing again its large 

 crop, as certainly as to the poor soil the power of still continuing 

 to produce its small crop. It is not that the natural alimentary 



