Theoretically of course it is perfectly easy to avoid or remedy these troubles. It is only necessary to render the ditches water-tight by puddling with clay, cement, or otherwise. But the heavy cost of this improvement forms a serious obstacle to its adoption by the ditch companies who are not themselves owners of land. Thus, extensive areas of lands which when first irrigated were among the most productive, have in the course of eight or ten years become almost valueless to their owners, to whom legislation thus far affords but distant promise of relief; although the case seems in equity to fall clearly within the limits of the laws governing trespass. _Permanent Injury to Certain Lands._—In cases like those alluded to the remedy usually available for higher ground-water does not always afford relief, even when otherwise available. Long-continued submergence produces in many soils effects which cannot easily, if at all, be overcome by subsequent aeration. This is most emphatically true of soils containing a large proportion of ferric hydrate in the finely divided form in which it is usually present in “red” soils. The first effect of the stagnation of water in such lands (as already explained in a former chapter 3, p. 45) is to set up a reductive (bacterial) fermentation of the organic matter of the soil, transforming the ferric into ferrous hydrate, which in the presence of the carbonic acid simultaneously formed, becomes ferrous carbonate, readily soluble in carbonated water. That this compound is poisonous to plant growth, has been stated (chap. 3, p. 46). The carbonates of lime and magnesia are simultaneously dissolved by the same, as is also calcic phosphate, the usual form in which phosphoric acid is present in the soil. Under the influence of partial aeration from the surface, the ferrous carbonate is slowly re-transformed into ferric hydrate, aggregated in the form of spots or concretions of “bog ore” (see chapter 5, p. 66). In this process the greater part of the phosphoric acid of the soil is also abstracted from its general mass and concentrated in the bog ore (chap. 5, p. 65), in which it is wholly unavailable to vegetation, and cannot be made available while in the ground, by any known process. The soil is therefore permanently impoverished in phosphoric acid; it is also deprived of its content of ferric hydrate, and is transferred from the class of “red” to that of “white” soils, well known everywhere to be unthrifty and to require early fertilization. Not only is this true, because of their almost invariable poverty in phosphoric acid, but also usually in lime, which like the iron, if not leached out, is aggregated into concretions in the subsoil, leaving the surface soil depleted of this important ingredient. The humus, also, is either destroyed or at least “soured” at the same time.