104 CALCAREOUS MANURES— PRACTICE. 



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 ordinary marl had been required for an acre, 

 and 1 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 sustained. 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 supposed power of their causes, I may 

 safely assert that in not a single case, in the tide-water region, of a judi- 

 cious 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 calcare- 

 ous earth as manure. 



But there is still another exception, if it be one, to admit, 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 experiments which have been made witiiin 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 proba- 

 bly is, that there is a general difference of chemical constitution between 

 even lands of like apparent texture and qualities, above and below the 

 falls. Of the lands above, my knowledge is but slight, and founded only 

 on general and slight personal observation, or the report and better inform- 

 ation of practical cultivators. But judging from such uncertain lights, I would 

 infer that the lands above the falls were much less acid than those below, 

 even when as poor. The growth of pine and of sorrel is more scarce on 

 lands above the falls ; and gypsum often acts there on natural soils, and 

 lime (in some known trials) has produced but slight benefit. On the 

 contrary, gypsum is scarcely ever operative on any natural soil below the falls, 

 (that is on none of the great body of acid soil,) and lime never fails to act 

 on these same lands. 



The most important observation to be made on the disproportion of 

 causes and effects, in the tide-water region, is in regard to good neutral 

 soils, and especially as to that best class known by the common name of 

 " mulatto land." On such soils, which constitute the chief value of the 

 best farms of James river, the applications of lime have been the most 

 extensive, and always highly effective. 



The fact that the effects of calcareous manures so generally exceed in 

 measure the supposed power of their causes, would seem to indicate that 

 some other kind of action of calcareous earth as manure operates^ in addition 

 to all those set forth in chapter viii. This I think is more than probable. 



Dismissing then from further consideration such exceptions (whether 

 real or apparent) to general rules, I will return to stating the results of 

 applying marl as they have occurred almost without exception in my own 

 practice, and which are confirmed by the concurrence of all known and cer- 

 tain testimony in regard to practical operations in the marl region of 

 Virginia. 



Under like circumstances in other respects, the benefit derived from marl- 

 ing will be in proportion to the quantity of vegetable or other putrescent 

 matter given to the soil. It is essential that the cultivation should be mild. 



