(corn) produced; by adding to this soil an ordinary dressing of manure’ this was reduced to 613 pounds, and by adding a small amount of sodium nitrate it was reduced to 585 pounds.  If so large a reduction could be secured in practice, it would seem to justify the use of commercial fertilizers in years when the dry-farm year opens with little water stored in the soil.  Similar results, as will be shown below, were obtained by the use of various cultural methods.  It may therefore, be stated as a law, that any cultural treatment which enables the soil-water to acquire larger quantities of plant-food also enables the plant to produce dry matter with the use of a smaller amount of water.  In dry-farming, where the limiting factor is water, this principle must he emphasized in every cultural operation.

Methods of controlling transpiration

It would appear that at present the only means possessed by the farmer for controlling transpiration and making possible maximum crops with the minimum amount of water in a properly tilled soil is to keep the soil as fertile as is possible.  In the light of this principle the practices already recommended for the storing of water and for the prevention of the direct evaporation of water from the soil are again emphasized.  Deep and frequent plowing, preferably in the fall so that the weathering of the winter may be felt deeply and strongly, is of first importance in liberating plant-food.  Cultivation which has been recommended for the prevention of the direct evaporation of water is of itself an effective factor in setting free plant-food and thus in reducing the amount of water required by plants.  The experiments at the Utah Station, already referred to, bring out very strikingly the value of cultivation in reducing the transpiration.  For instance, in a series of experiments the following results were obtained.  On a sandy loam, not cultivated, 603 pounds of water were transpired to produce one pound of dry matter of corn; on the same soil, cultivated, only 252 pounds were required.  On a clay loam, not cultivated, 535 pounds of water were transpired for each pound of dry matter, whereas on the cultivated soil only 428 pounds were necessary.  On a clay soil, not cultivated, 753 pounds of water were transpired for each pound of dry matter; on the cultivated soil, only 582 pounds.  The farmer who faithfully cultivates the soil throughout the summer and after every rain has therefore the satisfaction of knowing that he is accomplishing two very important things:  he is keeping the moisture in the soil, and he is making it possible for good crops to be grown with much less water than would otherwise be required.  Even in the case of a peculiar soil on which ordinary cultivation did not reduce the direct evaporation, the effect upon the transpiration was very marked.  On the soil which was not cultivated, 451 pounds of water were required to produce one pound of dry matter (corn), while on the cultivated soils, though the direct evaporation was no smaller, the number of pounds of water for each pound of dry substance was as low as 265.