PRACTICE IV 



EFFECT .OF COLOR ON TEMPERATURE OF A SOIL 



Fill a Avooden tray three by six feet and eight inches deep 

 with a very light-colored ^ gray silt loam, well pulverized. Divide 

 the tray lengthwise into halves. Divide each half into five or six 

 plots, and plant the same kind of seed — wdieat, oats, corn, §oy 

 beans, w^atermelons, etc. — in opposite plots, planting the same 

 number in each. Cover those in one half of the tray three fourths 

 of an inch deep and in the other one half inch deep. Then cover 

 the latter with one fourth inch of black soil so that all of the 

 light-colored soil is covered. Keep all parts of tray equally moist. 



The planting, observing, and recording the number of plants up 

 each morning and evening may be done the same as in Practice III. 



Place thermometers with bulbs at one, two, and four inches be- 

 low the surface and one with bulb one inch above the surface, 

 supported in a way that will not affect the temperature. Read 

 and record the temperature hourly from 6 a.m. to 6 p.m. 



Which soil shows the higher temperature ? Why ? 



Why can you see the corn rows on low black land sooner after 

 planting than upon the higher lighter colored land ? 



References. 



" Soils," Lyon and Fippin, pp. 130 and 456-458. 

 "The Soil," Hall, pp. 127-128. 



"Physical Properties of Soil," Warington, pp. 161-164. 

 " The Soil," King, pp. 230. 



^ We may get the same results by filling the tray with dark soil, a brown or black 

 silt loam, and by covering the one half with a verj^ light gray silt loam. 



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