USE OF SOIL MOISTURE BY PLANTS 



123 



POUNDS OF WATER LOST DAILY PER SQUARE FOOT 

 (Rate increases to flowering, then decreases.) 



It is to be remembered that, in this table, the initial 

 percentages are not in all cases the same, so that the dif- 

 ferent crops cannot be compared as to their power to 

 abstract water. The only legitimate use of the table is to 

 compare the quantities of water for each crop that were 

 lost in July, August and September the months of the 

 growing season. In the case of corn, the greatest loss came 

 in August; while in July and September, the loss was prac- 

 tically the same. In the case of sugar beets, the greatest 

 loss also came in August; the next in July, and the smallest 

 in September. In the case of wheat, the largest loss came 

 in July and the smallest in August. These variations are 

 readily explained by remembering that, under the climatic 

 conditions prevailing, the wheat matured in July and was 

 harvested in August, thus corresponding with the rates 

 of loss as shown above; while the corn and sugar beets 

 continued their vigorous growth into September. The 

 time of most rapid growth is usually the time of greatest 

 daily water use. 



91. The kind of crop. The kind of crop also influences, 

 materially, the rate at which water is taken from the soil. 

 No two crops appear to be exactly alike in their power to 

 absorb soil moisture. Much work is yet to be done on 

 this subject before really definite results can be given. 

 Meanwhile, some general laws have been observed which 

 can safely be stated, at least until further knowledge is 



