MARL. 30t 



to dung alternately ; in others, the two operations are done together, 

 or very close upon one another. There are some lands so fertile, 

 that they produce abundantly under the influence of lime alone. In 

 laying on lime, one general rule is, that the weather should be dry, 

 and the ground well drained ; the end of summer is probably the 

 most favorable season. To say nothing of the difficulty of spreading 

 the lime in wet weather, if it is at all fresh, its caustic qualities are 

 brought into immediate play by the moisture, and it destroys the 

 roots of living vegetables, and the organic elements of the soil ; and, 

 again, it is quite certain that lime produces very little effect upon 

 undrained and wet lands. In England, lime is very commonly used 

 upon fallows, in the course of the summer, and before sowing the 

 wheat for which fallowing is always a preparation. When it is given 

 to land destined for beet or potatoes, it is led out in the spring, and 

 spread before the young beet is transplanted, in the one case, the 

 seed-potatoes deposited, in the other. 



It is always matter of great moment to have lime spread evenly ; 

 a thorough harrowing and a double superficial ploughing incorporate 

 it sufficiently. According to M. Puvis, who has made a particular 

 study of the subject of liming, as practised in the department of the 

 Ain, a quantity of lime, amounting to 8,250 bushels, spread upon 

 seventy-seven acres of land, in the course of nine years, produced 

 so decided an improvement that the returns from winter-grain crops 

 became the double of what they had been before. 



Marl. Marl, in a general way, may be regarded as a mixture of 

 carbonate of lime and clay in very variable proportions. Occasional- 

 ly the clay^is replaced by sand ; whence the titles, sandy marl, argil- 

 laceous marl. The article, in short, contains from 15 to as many as 

 90 per cent, of carbonate of lime. It presents numerous shades of 

 color. Geologically speaking, it is usually met with in fresh-water 

 formations of the latest date — the upper strata of the Jura limestone 

 are frequently covered with deposites of argillaceous marls, and we 

 see its formation going on at the bottoms of lakes and ponds, at the 

 present day. 



The distinguishing property of a calcareous marl, whatever ad- 

 mixture of other matters it contains, is that of crumbling to pieces 

 under exposure to atmospherical influences. Every limestone rock 

 that has this property may be considered and employed as a marl. 

 The grand purpose of putting marl upon land is to supply it with the 

 calcareous element it wants. To marl land, is therefore tantamount 

 to liming it : the effect is the same. The value of the article is, 

 indeed, so well known, that considerable expense is constantly in- 

 curred to get at the beds of it that form strata in the crust of tae 

 earth, or that lie at the bottoms of lakes. It appears to have been 

 employed from the remotest antiquity. 



The reason why marl and marly limestones fall so completely 

 into powder, is obvious. If the mass, when wet, form a pasty mass- 

 it shrinks as it dries, and cracks in all directions ; if more consistent, 

 it is still always porous, and having imbibed a large quantity of rain 

 in the autumn, this congeals during the frosts of t.he succeeding win- 



