Duty of Water in Rice Culture 217 



where the number of cubic feet is the product of one 

 second -foot into the number of seconds in the season 

 of growth, and the number of bushels is the product 

 of the yield per acre into the number of acres irri- 

 gated. 



THE DUTY OF WATER IN RICE CULTURE 



The aquatic nature of the rice plant makes the 

 demands for water quite different from those of ordi- 

 nary agricultural crops, and so different are these 

 needs that the quantity of water required to bring a 

 crop to maturity is determined by quite different 

 factors. The duty of water, therefore, in rice culture 

 could not consistently be considered in connection with 

 that of ordinary crops. 



The normal habitat of this plant is low, swampy 

 lands, where the surface is more or less continuously 

 under water, and where such lands are available under 

 suitable conditions for rice culture, they are largely 

 brought into requisition for this purpose ; but the 

 seeding of the ground and the harvesting of the crop 

 make it needful that the fields shall be drained' at 

 times and at others flooded. Under these conditions, 

 there can be but little waste from seepage, and the 

 chief demands for water are created by the loss from 

 evaporation from the surface of the water, from the 

 growing crop, and from the wet soil when the fields 

 have been drained, together with the amounts which 

 are required for reflooding the fields after they have 

 been drained. Occasionally threatened attacks upon 



