Prairie Farmer,

Vol. 56 No. 2

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Dew and Soil Moisture.

Bulletin No. 6 of Missouri Agricultural College Farm is devoted to an account of experiments intended to demonstrate the relation of dew to soil moisture. Prof. Sanborn has prosecuted his work with that patience and faithfulness characteristic of him, and the result is of a most interesting and useful nature.

The Professor begins by saying that many works on physics, directly or by implication, assert that the soil, by a well-known physical law, gains moisture from the air by night. One author says "Cultivated soils, on the contrary (being loose and porous), very freely radiate by night the heat which they absorb by day; in consequence of which they are much cooled down and plentifully condense the vapor of air into dew." Not all scientific works, however, make this incautious application of the fact that dew results from the condensation of moisture of the air in contact with cooler bodies. Farmers have quite universally accepted the view quoted, and believe that soils gain moisture by night from the air. This gain is considered of very great importance in periods of droughts, and is used in arguments favoring certain methods of tillage.

Professor Stockbridge, at the Massachusetts Agricultural College, carried on very valuable and full experiments in test of this general belief, and arrived at results contradictory of this belief. He found, in a multitude of tests, that in every instance, save one, for the months from May to November, that the surface soil from one to five inches deep, was warmer than the air instead of cooler, as the law requires for condensation of.................

 

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