610 STATE BOARD OF AGRICULTURE. 



even in different degrees of shade, so that the reflection is considerably 

 i-educed, if not entirely eliminated, their temperatnre is about the same, 

 irrespective of their moisture content, and that it is higher than that 

 of the uncolored soil whose reflection is very great and whose moisture 

 content is small. 



The question might now be asked why ]H'at did not also have a much 

 higher temi>erature than the uncolored soil. It would have had if it 

 were not for its water holding ])eculiarities. Peat or muck has not only 

 a very great water holding capacity but also has the ability to retain 

 and absorb water on the surface, which on account of its slow but con- 

 tinuous evaporation, tends to keep the temiM}rature down. This fact 

 is well illustrated in the folhnnng experiments. A piece of ground 

 \\as covered with a thin layer of peat while another piece was covered 

 with a thin layer of white sand. The temperature records taken several 

 liuies throughout the summer show that both plots at the depth of 7 

 inches were equally warm, with a slight difference in favor of the plot 

 covered with the white sand. In another experiment, instead of using 

 l)eat, dark colored sand was employed. The results show that the tem- 

 I)erature of the dark covered soil was from 1° to 7° F., higher than that 

 of the white covered soil. In still another experiment, wooden boxes 

 13 inches square and 2 inches high were filled with white sand, black 

 dyed sand, and ]>eat, in the dry condition, and placed out in the sun 

 and the temixn-atures ^\■ere taken many times during the day for several 

 days. The results show that the temperature of the black sand was 

 always about 5° to 6° F., higher than that of the white sand, while the 

 temj^erature of the peat was lower than that of the black sand and only 

 about 1° or 2° F., higher than that of the white sand. The results 

 under the investigation of the temperature of the different types of 

 soil show also that when the peat was covered with a thin layer of a 

 sandy soil its temperature was little higher during the warmest part of 

 the year tlian that of the other soils. All these facts go to prove, there- 

 fore, that the high heat absorptive power of pure peat, on account of 

 its black color, is considei>ably reduced by its other properties and con- 

 sequently its temi^erature is l)elow that of the other types of soil. 



The color of soils differs considerably. It merges into different shades 

 of the same color or into the various colors of the spectrum. The differ- 

 ent colors of the spectrum such as blue, green, red, yellow, etc., are 

 found in soils. Some of them occur very rarely. There are various 

 causes of these colors, chief of which are the humus and the iron com- 

 pounds. All these natural colors, as shown by the present investiga- 

 tion and by the research under absorption, play a very important part 

 in the heat relationship of the soil. 



Nothing very definite can be said as to the influence of color on the 

 temperature of soils covered with vegetation. An experiment was com- 

 menced to ascertain an answer to this question but it was too late in 

 the season and the results obtained cannot be absolutely relied ujmn. 

 It would seem, however, that extreme shades of color, such as black 

 and white, would impart to the soils different heat relationships and 

 especially during the early part of jilant growth, which is the most 

 important in the life history of plants. Even when the vegetation is 

 well .-idvanced. if the planting has not been t(Mi thick so the sun ravs 



