When it is impossible to add humus to the soil through the medium of organic manures, as is often the case in city back yards, recourse may be had to one of the many brands of prepared humus obtainable from seedsmen. Liming is also considered to be good for sandy soils, as the lime exercises a binding influence on the coarse particles. Of course when clay is available it is good to add it, and mix thoroughly with the sand, but it is seldom that clay is present in near enough proximity to make this practice a paying proposition. Compacting sandy soils, by means of a roller on large areas, or by means of the feet in the case of small plots, is good horticultural practice. Clay soils, like the preceding, are greatly improved by the addition of organic matter. It should be applied in the fall, in the form of strawy stable manure, and buried deeply. Leaves also are a valuable addition. Liming is good, as this causes the flocculation of the clay particles and renders the soil more open and permeable by air and water. The addition of sand, sifted coal ashes, or wood ashes serves the same purpose. Clay soils are benefited by being plowed or spaded in the fall and left rough over the winter. This allows the frost to penetrate more readily, resulting in the breaking up and disintegration of the clods. Another advantage of fall plowing in the case of land of this type is that by so doing it dries out more rapidly in the spring and it is possible to get your crops planted earlier. Muck and swamp soils are frequently waterlogged, and before they will support a crop it is necessary to underdrain them; but as this is an operation that is scarcely practicable for those for whom this book is written, it will not be dealt with here. As there is always a lack of basic salts in this type of soil, liming is practised, usually to good advantage.