160 RESULTS HAVE CONFORMED TO THEORY. 



nures (as may be observed in some of the reported experiments), 

 but they have neither been frequent, uniform, nor important. 



[But in nearly all such cases of disproportion between causes 

 and effects in the use of marl, the manner of variation has been 

 in the effects surpassing the anticipated power of the causes (as 

 previously inferred from reasoning and in advance of any practice), 

 and in very few, if indeed any cases, of the contrary operation, of 

 the results falling short of what might have been inferred from the 

 theory of the action of calcareous manures. For such variation as 

 this, it may be that no reader will require either excuse or explana- 

 tion -, nevertheless it is as much due to truth that it should be 

 stated, as if the opposite kind of difference existed. 



Before my earliest trials, or practical knowledge, of the effects 

 of marl, I was well assured, by my theoretical reasoning, that this 

 manure would correct the acidity of poor soil, and enable it to be 

 enriched by putrescent manures. But I was still totally at a loss 

 to know, or to guess, how much calcareous earth would be required 

 for that result, or how much time might be required for the suffi- 

 cient quantity to produce its full effect ; and there were grounds to 

 fear that the quantity of the manure and time for its operation, 

 and consequently the cost compared to profit, would be much 

 greater than after-experience has shown. If 1000 bushels of ordi- 

 nary marl had been required for an acre, and 10 years' time for that 

 application to raise the product to double its previous rate, the 

 theory of the action of calcareous manures would have been sus- 

 tained. But in fact, as great effect as this has been usually pro- 

 duced (in judicious and proper practice), by measures of marl and 

 of time less by three-fourths than those just stated. And thus, 

 while effects have almost universally exceeded in measure the sup- 

 posed power of their causes, I may safely assert that in not a sin- 

 gle case, in the tide-water region, of a judicious application of 

 marl or lime, has it been known that the effect fell short of what 

 would be indicated by my theory of the action of calcareous earth 

 as manure. 



But there is still another exception to admit, if it be one, or of 

 apparent want of accordance between theory and practice; and 

 unluckily, this case is of the effects falling short of the supposed 

 power of causes. There has as yet been made but little use of 

 lime in the region immediately above the granite ridge which forms 

 the lower falls of our eastern rivers, But almost all the failures 

 of lime to act that have been heard of, or of effects falling much 

 short of what were expected and are usual, are among the few ex- 

 periments which have been made within fifty miles above the 

 granite ridge. While truth requires that the fact of these failures 

 should be stated, I pretend not to account for them. It may be 

 the case, and probably is, that there is a general difference of 



