CALCAREOUS MANURES— PRACTICE. 1Q3 



enough vegetable matter to combine with and fix in the soil, c=iuses, by its 

 excess, all these injurious effects. 



CHAPTER X. 



RECAPITULATION OF THE EFFECTS OF CALCAREOUS MANURES, AND DIRECTIONS FOR 

 THEIR BIOST PROFITABLE APPLICATION. 



Proposition 5— continued. 



From the foregoing experiments may be gathered most of the effects, 

 both injurious and beneficial, to be expected from calcareous manures, on 

 the several kinds of soils there described. Information obtained from state- 

 ments in detail of agricultural experiments, is far more satisfactory, to the 

 attentive and laborious inquirer, than a mere report of the general opinions 

 of the experimenter, derived from the results. But however preferable may 

 be this mode of reporting facts, it is necessarily deficient in method, clear- 

 ness, and conciseness. It may therefore be useful to bring together the 

 general results of these experiments in a somewhat digested form, to serve 

 as rules for practice. Other effects of calcareous manures will also be 

 stated, which are equally established by experience, but which did not be- 

 long to any one accurately observed experiment. 



The results that have been reported confirm in almost every particular 

 the chemical powers before attributed to calcareous manures, by the theory 

 of their action. It is admitted that causes and effects were not always 

 proportioned — and that sometimes trivial apparent contradictions were pre- 

 sented. But this is inevitable, even with regard to the best e.stablished 

 doctrines, and the most perfect processes in agriculture. There are many 

 practices universally admitted to be beneficial ; yet there are none, which 

 s^e not found sometimes useless, or hurtful, on account of some other at- 

 tendant circumstance, which was not expected, and perhaps not discovered. 

 Every application of calcareous earth to soil is a chemical operation on a 

 great scale. Decompositions and new combinations are jaroduced, and in 

 a manner generally conforming to the operator's expectations. But other 

 and unknown agents may sometimes have a share in the process, and thus 

 cause unlooked-for results. Such differences between practice and theory 

 have sometimes occurred in my use of calcareous manures, (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 surpass- 

 ing the anticipated power of the causes, (as previously inferred from rea- 

 soning and in advance of my practice,) and in very fcw, 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 

 explanation; 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 eflfects of marl, 

 I was well assured 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 re- 

 quired for that result, or how much time might be required for the sufficient 



