Another method of applying sewage to the surface of the ground is to lead it in channels between narrow beds on which vegetables have grown. These beds are made about eight feet wide with two rows of root crops, such as turnips or beets, set back about two feet from the edge. The beds are made by properly plowing, the channels between the beds being back-furrowed. Here, again, the principle of intermittent application is essential, and the area to be provided is the same as already given for the surface irrigation. Three beds should be provided, as before; but, in general, no provision need be made for carrying off the sewage at the lower end of the beds, since it may be safely assumed that all of the sewage will be absorbed by the soil. Of course, a sandy soil will absorb more water than a clay soil, and if the soil is entirely clay, it is not suitable for such treatment. Sewage passed over the surface of clay soil, however, will, in the course of a few months, so modify the clay as to convert it into a loam, and in this way increase its absorptive power. When possible, it is desirable to have a plot of plowed ground over which the sewage may pass before reaching the beds, so that the grosser impurities may be left behind and harrowed in or plowed under. If proper regard is paid to intermittent application, no danger from odors need be feared, and the repeated plowing in will increase immensely the fertility of the soil. Nor need one be afraid that all of the manurial elements will be left behind on this plowed ground. About two thirds of the organic matter in sewage is in solution, and this will be carried onto the beds just as if passage over the plowed ground had not occurred. _Artificial sewage beds._