The doomuteea is of a light-brown colour, soon powders into fine dust, and requires much more outlay in manure and labour than the muteear. The oosur soil appears to be formed out of both, by a superabundance of one or other of the salts or their bases, which are brought to the surface from the beds below, and not carried off or taken back into these beds. It is known that salts of ammonia are injurious to plants, unless combined with organic acids, supplied to the soil by decayed vegetable or animal matter. This matter is necessary to combine with, and fix the ammonia in the soil, and give it out to plants as they require it.
It is possible that nitrates may superabound in the soil from the oxydizement of the nitrogen of a superfluity of ammonia. The people say that all land may become oosur from neglect; and when oosur can never be made to bear crops, after it has been left long fallow, till it has been flooded with rain-water for two or three seasons, by means of artificial embankments, and then well watered, manured, and ploughed. When well tilled in this way, all but the very worst 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.