85

or gravelly ingredients of loams are of no use.Some think, it is true, that pebbles in a fieldserve to preserve or communicate heat. Thisuse, however, is not sufficiently ascertained.

CHALKY LOAM.

The best manure for this soil is clay, or ar-gillaceous marl*, if clay cannot be had; be-cause this soil is defective principally in the ar-gillaceous ingredient. In Ireland , chalky soilsor loams seldom occur, but light limestone soilsfrequently, and these do not differ essentiallyfrom chalky loams poor in argill: clay, there-fore, and often the soil of bogs, should serveas a manure for them.

SANDY SOILS.

The best manure for these is calcareousmarlf, which exactly corresponds with ourtheory; for these soils want both the argillace-ous and calcareous ingredients ; and this marl

* 4 th Young’s Eastern Tour, 404.t Ibid. 401, 412.

G 3