226 IRRIGATION PRACTICE 



When the water used was increased from 10 to 35 

 inches, there was increase of less than one-tenth of 1 per 

 cent of sugar and a difference of only about 1 per cent 

 in the purity of the juice. Moderate irrigations are 

 undoubtedly quite as satisfactory as larger ones in pro- 

 ducing beets with a high percentage of sugar. Potatoes 

 and other crops yielding much sugar, contain the highest 

 percentages of sugar when medium quantities of water 

 are used. In general, sweeter crops are produced by 

 moderate than by either very small or very large irriga- 

 tions. 



134. Starch. Starch, one of the important foods of 

 man, is found generally in plants. In potatoes, sugar 

 beets and similar crops it is a chief constituent. In the 

 dry matter of sugar beets the percentage of starch increases 

 very rapidly with the increase in irrigation. That is, where 

 large quantities of water are applied to sugar beets, much 

 of the sugar is rapidly converted into starch. This is 

 another argument against the use of large quantities of 

 water in irrigation. In the dry matter of potatoes, grown 

 largely for starch, the percentage of increase hi starch, 

 due to increasing irrigation, is much slower. In general, 

 the starch content increases as irrigation increases. 



135. Woodiness. The woody material or crude fiber 

 of plants, made up largely of cellulose, is of little value 

 as a food. It is influenced very strongly by irrigation 

 water. As the irrigation water applied to a crop increases 



