72 
ELEMENTS OF AGRICULTURE, 
38 Calcareous marl is that which agrees best with clay 
soils. Clayey marl and marly clay are best suited to 
gravelly and sandy lands ; but the great quantity that it is 
often necessary to employ in this case leads to such expense 
as not always to permit the farmer to make such ameliora¬ 
tions. 
39. In case that it is desired to employ calcareous sub¬ 
stances on light lands, they should generally be used in 
small quantities; for these soils are naturally disposed to 
dryness, and to decompose manures ; whereas, as we have 
seen, the reverse is the case with stiff lands. 
40. Marl properly so called suits, as it were, every kind 
of soil, giving porosity to the clayey and compactness to 
the silicious. 
41. Though marl is adapted to the amelioration of cer¬ 
tain soils, it does not follow that it is fertile in itself. On 
the contrary, a soil containing too much of it would pos¬ 
sess the defects of lands too highly calcareous, and it could 
only be rendered productive by unusual quantities of ma¬ 
nure. 
42. Marly earths favor the vegetation of certain plants 
that can serve as indicators to the farmer in search of 
marl. 
43. We have just demonstrated that the action of marl 
depended upon its composition, and that of the soils to 
which it is applied. As to the quantity that should be 
employed, it is subordinate to three principal circum¬ 
stances, namely: 1. The nature of the soil. 2. The na 
ture of the marl. 3. The durability desired for the ame¬ 
lioration. This durability depends not only on the quan¬ 
tity of the marl to be employed, but also upon its richness 
Generaliv, from twenty to sixty double-horse cart-loads 
are used; but soils on which marl is used only for its clay 
require a much larger quantity. 
44. That marl may be effective, the soil must not b€ 
