kinds
of _oosur_ are said to bear tolerable crops. In the midst of a plain
of barren oosur land, which has hardly a tree, shrub, or blade of
grass, we find small _oases_, or patches of low land, in which
accumulated rain-water lies for several months every year, covered
with stout grasses of different kinds, a sure indication of ability
to bear good crops, under good tillage. From very bad _oosur_ lands,
common salt or saltpetre, or both, are taken by digging out and
washing the earth, and then removing the water by evaporation. The
clods in the muteear soil not only retain moisture, and give it out
slowly as required by the crops, but they give shelter and coolness
to the young and tender shoots of grain and pulse. Of course trees,
shrubs, and plants, of all kind in Oude, as elsewhere, derive
carbonic acid gas and ammonia from the atmosphere, and decompose
them, for their own use, in the same manner.

In treating of the advantages of greater facilities for irrigation in
India, I do not recollect ever having seen any mention made of that
of penetrating by wells into the deep deposits below of the soluble
salts, or their bases, and bringing them to the surface in the water,
for the supply of the plants, shrubs, and trees we require. People
talk of digging for valuable metals, and thereby "developing
resources;" but never talk of digging for the more valuable solutions
of soluble salts, to be combined with the organic acids already
existing in the soil, or provided by man in manures--and with the
carbonic acid, ammonia, and water from the atmosphere--to supply him
with a never-ending succession of harvests. The practical
agriculturists of Oude, however, say, that brackish water in
irrigation is only useful to tobacco and shama; and where the salts
which produce it superabound, rain-water tanks and fresh-water rivers
and canals would, no doubt, be much better than wells for irrigation.
All these waters contain carbonic acid gas, atmospheric air, and
solutions of salts, which form food for plants, or become so when
combined with the organic acids, supplied by the decayed animal and
vegetable matter in the soil.

Soils which contain salts, which readily give off their water of
crystallization and _effloresce_, sooner become barren than those
which contain salts that attract moisture from the air, and
deliquesce, as chlorides of calcium and magnesia, carbonates and
acetates of potassa, alumina, &c. Canals flowing over thes