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PRACTICE 4 



Effects of Color of Soil on Temperature. 



Fill large wooden tray 6 feet long, 3 feet wide and 6 inches deep with 

 very light colored soil, gray silt loam, well pulverized. Divide the tray 

 lengthwise into halves and divide each half into six plots and plant 

 the same kind of seed in the opposite plots putting the same number 

 in each but covering those in one half of the tray I inch and the 

 other, $ inch deep. Then cover the latter with I inch of black 

 soil so that all of the light colored soil is covered. Observe the num- 

 ber of plants up each morning and evening, keeping a careful record 

 of the number coming up each day. 



Select a clear day and make observations on the temperature of 

 each half of the tray. Insert thermometers 1, 2, and 4 inches in depth, 

 also place one, one inch above surface of each kind of soil, and take 

 hourly readings from 8 a. m. to 5 p. m. Keep all parts of tray 

 equally moist. 



Each student may look after the planting of a single plot but he 

 must make observations on all plots in the tray and keep results in 

 tabular form. 



Which tray shows the higher temperature? Why? 



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

 planting than upon the higher lighter colored soil? 



