Hellriegel, in
1883, confirmed this law and laid down the law that poor plant
nutrition increases the water-cost of every pound of dry matter
produced. It was about this time that the Rothamsted Experiment
Station reported that its experiments had shown that during periods
of drouth the well-tilled and well-fertilized fields yielded good
crops, while the unfertilized fields yielded poor crops or crop
failures--indicating thereby, since rainfall was the critical
factor, that the fertility of the soil is important in determining
whether or not with a small amount of water a good crop can be
produced. Pagnoul, working in 1895 with fescue grass, arrived at the
same conclusion. On a poor clay soil it required 1109 pounds of
water to produce one pound of dry matter, while on a rich calcareous
soil only 574 pounds were required. Gardner of the United States
Department of Agriculture, Bureau of Soils, working in 1908, on the
manuring of soils, came to the conclusion that the more fertile the
soil the less water is required to produce a pound of dry matter. He
incidentally called attention to the fact that in countries of
limited rainfall this might be a very important principle to apply
in crop production.
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