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first, that all growing plants are made up largely of water. Green 

 grass or clover contains from 80 to 90 per cent of water. Many 

 of our common fruits, such as strawberries, raspberries, peaches 

 and pears contain from 80 to 92 per cent of water. The impor- 

 tance of this to the farmer is seen in the fact that when he sells 

 such crops he is mainly disposing of water and a small amount of 

 mineral salts. As one prominent fruit grower puts it, he sells in 

 his fruit barrels of water with a little flavoring extract in it. The 

 water held in the tissues of the plant, however, represents but a 

 small part of the total amount needed by the plant ; a very large 

 amount is evaporated or transpired through the foliage during the 

 period of growth. 



It has been estimated that a crop of hay at two tons per acre, or 

 about six and one-half tons of fresh grass, will evaporate during 

 its season of growth about 525 tons of water ; that an average 

 crop of wheat, of 720 pounds of grain and 1,500 pounds of straw 

 to the acre, will evaporate about 260 tons of water, or, in other 

 words, according to these estimates, every ton of green grass 

 evaporates through its foliage during the period of growth about 81 

 tons of water, and in drying this ton of grass loses about two- 

 thirds of its weight, so that one-third of a ton of hay (667 pounds) 

 utilizes in its growth about 81 tons of water. An inch of rainfall 

 is equal to 113 tons of water per acre. The above figures indicate 

 that the water evaporated by an acre of grass (6^ tons) would equal 

 about 4.6 inches. In some cases this amount of water is more than 

 the total rainfall during the period of time in which the crop makes 

 its growth. These figures, of course, only represent averages. In 

 very moist times evaporation would be checked and in dry times 

 it would be increased. In other words, at times when the plant 

 uses water most rapidly there is the least available amount from 

 the rainfall. 



Professor King of Wisconsin has shown that the amount of 

 water transpired through the foliage and evaporated from the soil 

 by some of our common crops is as follows, when estimated on the 

 basis of dry matter in the crop : — 



Dent corn per ton of dry matter, 2.64 inches of water. 

 Flint corn per ton of dry matter, 2.14 inches of water. 

 Red clover per ton of dry matter, 4.03 inches of water. 

 Oats per ton of dry matter, 4.76 inches of water. 

 Potatoes per ton of dry matter, 4.73 inches of water. 



If we assume a fair yield of red clover to be 10 tons per acre 

 (green) with 25 per cent of dry matter (equal to 2^ tons per acre), 

 the clover crop would use about 10 inches of water in its growth. 



