This is a valuable application to the soil. For wheat it is very
important, except on soil containing a large proportion of calcareous
matter. Usually air-slaked, and applied as a top-dressing, or plowed or
harrowed in, its effects are important. On moist, sour land, producing
wild grass, it corrects the acidity, introduces other grass, and
prepares the soil for cultivation. On hard, stiff lands, it has a
tendency to make them friable, and keep them in a mellow condition, thus
saving more than its cost, in the labor of cultivation. Very valuable
in a compost heap. So much may be applied as to burn the soil and prove
injurious. It will not do as a substitute for everything else. See
further on "Manures."