2l6 



Bulletin 37. 



and the relative humidity percentages those of the Weather 

 Bureau : 



DURING I9OO-19OI. 



During the two previous years a green-manuring crop was 

 grown in the other two orchards on the farm. Since it was found 

 that the soil in these orchards would not only produce a heavy 

 winter crop, but became thoroughly moistened to as great a depth 

 as in the smaller orchard, the soil of which had been left bare, the 

 latter was sown to clover (Melilotus indica) November 6. The 

 seeding was followed by an irrigation, and water was applied fre- 

 quently enough until March 29 to keep the crop growing well. 

 During this period water to the depth of four feet was applied. 

 The green-manuring crop was turned under April 6. As shown 

 by the accompanying illustration, the clover was twenty to thirty 

 inches high, and very thick upon the ground. Judging by the 

 amount applied the previous winter, the clover consumed, during 

 the four months of its growth, about one foot more water than 

 evaporated from the surface of the bare soil from December 16 to 

 March 5, 1899. 



DISCUSSION OF PRINCIPLES INVOLVED. 



Reasons for Favorable Results. 



The favorable results from the experiments outlined above 

 were due to several factors. At first thought, it seems marvelous 

 that trees not only could endure such dry, hot weather, but grow 

 thriftily for eight months without their roots receiving any addi- 

 tional water in the meantime. But their ability to do this was 

 simply the outcome of following natural laws. 



