One of the very earliest experiments on transpiration, conducted by
Woodward in 1699, showed that it required less water to produce a
pound of dry matter if the soil solution were of the proper
concentration and contained the elements necessary for plant growth.
Little more was done to answer the above questions for over one
hundred and fifty years. Perhaps the question was not even asked
during this period, for scientific agriculture was just coming into
being in countries where the rainfall was abundant. However,
Tschaplowitz, in 1878, investigated the subject and found that the
increase in dry matter is greatest when the transpiration is the
smallest. Sorauer, in researches conducted from 1880 to 1882,
determined with almost absolute certainty that less water is
required to produce a pound of dry matter when the soil is
fertilized than when it is not fertilized. Moreover, he observed
that the enriching of the soil solution by the addition of
artificial fertilizers enabled the plant to produce dry matter with
less water. He further found that if a soil is properly tilled so as
to set free plant-food and in that way to enrich the soil solution
the water-cost of dry plant substance is decreased.
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