Black alkali is very common in California in
alkali lands. In lands which show their quality by good cropping, there
is no reason to apprehend black alkali nor to use gypsum to prevent its
occurrence. The use of gypsum does stimulate the growth of alfalfa and
makes its product greater just as you observe in the experience of your
neighbors, but the more they use up the land now the less they will have
later, unless they resort to regular fertilization to restore what has
been exhausted. But even that may be a good business proposition.
What Gypsum Does.
I intend to fertilize alfalfa and should like to know about gypsum. I
have heard it stimulates the growth temporarily but in three or four
years hurts the land. I have heavy land.
The functions of gypsum are: (a) to supply lime when the soil lacks it;
(b) to make a heavy soil more mellow, and (c) to act upon other soil
substances to render them more available for plant food. These are some
of the soil aspects of gypsum; it may have plant aspects also. It is too
much to say that gypsum hurts the land; it does, however, help the plant
to more quickly exhaust its fertility, and in this respect is not like
the direct plant foods which comprise the true fertilizers - one of
which gypsum is not. It might be best for your pocketbook and for the
mechanical condition of the soil to use it, but do not think that it is
maintaining the fertility of the land (a service which we expect from
the true fertilizers) except as it may supply a possible deficiency of
lime.
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