THE SOUTHERN PLANTER. 517 



I860.] 



°f falling into powder when exposed to the 

 air, or forming pasty mud when saturated 

 with water, and acts very like lime in 

 the process of slaking, without giving off 

 heat. 



A marl is valuable in proportion to the 

 amount of carbonate of lime that it contains. 

 Take a piece of the substance suspected to 

 contain the carbonate, large as an acorn, 

 throw it into a tumbler or wine-glass, and 

 cover in with water ; after the air has es- 

 caped from the interstices, add a few 

 drops of any acid, say nitric or muriatic, 

 or either of these being wanting, strong vin- 

 egar may suffice ; then, if there should be 

 a disengagement of gas, or effervescence, it 

 is pretty sure evidence of the presence of 

 carbonate of lime. * * . * * * 



In deposits of marl there are frequently 

 different layers, varying in appearance, 

 thickness, and composition. The lower 

 strata are often richer in lime than the up- 

 per. An agrillaceous layer sometimes over- 

 lies one that is sandy or stiff'. Sea-sands 

 are, in many cases, applied to the soil with 

 great advantage, and it is not surprizing, 

 for they are frequently composed of minute 

 fragments of shells, comminuted corals, and 

 the remains of minute organisms, which 

 are fuond inhabiting the ocean — Nature's 

 great reservoir of life. 



But the action of marl cannot be entirely 

 owing to the carbowate of lime. There are 

 effects due to other causes, and it would be 

 strange indeed, considering the origin of 

 these fertilizers, if they did not contain 

 some of the more evanescent principles of 

 organic life. Mr. Payen and Boussingault, 

 both celebrated chemists, instituted a series 

 of inquiries into the composition of marls, 

 from different localities, and found nitrogen 

 in all. " It were therefore very proper, in 

 analyzing marls, clalk, &c, to have an eye 

 to their organic, or azotic, as well as to their 

 mineral constituents. There can be very 

 little question of the azotized elements be- 

 ing at the bottom of the really wonderful 

 fertilizing influences of the marls of certain 

 districts." (Boussingault, Rural Econ- 

 omy.} 



It would be still more surprising if a sub- 

 stance less ephemeral in its nature, and 

 not less important, should not be found 

 more constantly in limestones and marls 

 than former analysis has shown. Phospho- 

 ric acid at all times complicates analysis, is 

 difficult to appreciate correctly, and has 



doubtless been largely overlooked. But 

 there is higher evidence of its almost uni- 

 versal presence than chemical tests, for 

 wherever organic remains are found, it is 

 a sure indication of that singularly inter- 

 esting substance, phosphorus, to which we 

 attach as important a role, if not a higher 

 one, than that atributed to nitrogen, by the 

 celebrated authorities mentioned above. 



Marl, after ext; action from the pit, 

 should be exposed as long as possible to the 

 action of the atmospheric agents. A sum- 

 mer's heat and a winter's cold, previous to 

 spreading, making its immediate action 

 manifest; but its durability is dependent 

 upon its contents and the quantity applied. 

 According to Mr. Parvis, who has written 

 an interesting and useful pjaper upon marl, 

 the quantity to be applied depends upon 

 the quantity of lime already existing in the 

 soil and the richness of the marl in lime. 

 He says that any soil which contains less 

 than nine to ten per cent, of lime may re- 

 ceive a dose, or successive doses, until they 

 are brought up to that point. Lord Kanies 

 mentions a particular instance of the con- 

 tinued beneficial effects of calcareous ma- 

 nure for one hundred and twenty years, and 

 Johnson quotes the words of an intelligent 

 and experienced farmer, that certain lands 

 in Scotland " would never forget an appli- 

 cation of forty to sixty bushels of lime to 

 the acre." 



Lime appears to change the inert organic 

 matter in the soil, and give durability to 

 their action far beyond what w T ould have 

 been the case without the presence of that 

 mineral. It also changes the relations be- 

 tween the other mineral constituents of the 

 soil, and is an essential element of plant 

 food; but there are other substances quite 

 as necessary to healthy vegetation. It fol- 

 lows, then, that whoever may expect to 

 harvest large crops immediately from the 

 addition of lime to poor land will surely be 

 deceived. The proportion of marl or lime 

 to be added to a soil should be in accord- 

 ance with the amount of organic matter al- 

 ready existing in it, or that may be con- 

 tributed ; in other werds, the lime should 

 progress pari passu, ; and by following 

 such a course, the land may be brought to 

 a state of permanent fertility, to which it 

 never could be carried by farm-yard manure 

 alone. What would be an over-dose of 

 lime to one field would be a light dressing 

 for another. An over-dose of marl or 



