12 CKOP PLANTS FOR PAPER MAKING. 



RICE STRAW, 



Rice straw may be regarded as one of the most promising crop 

 materials available for paper making at the present time. In China 

 and Japan this material has been employed for many years. There 

 has been considerable discussion about its use in the United States, 

 but up to the present time no commercial plant has been constructed 

 for the purpose. Private experimenters have produced excellent 

 qualities of book and writing papers from it, more particularly in 

 combination with sulphite pulp and cotton-hull fiber. In the experi- 

 ments of the Department, yields running approximately from 32 to 40 

 per cent have been secured. Not less than 35 to 36 per cent could be 

 expected in practice. The character of the long fiber of this straw is 

 shown in figure 2. Pith cells are also present in rice straw, but not 

 in such proportion as in cornstalks. Indeed, it has been found per- 

 fectly feasible to produce paper without attempting to remove the 

 pith cells, but merely combining the straw pulp with a suitable quan- 

 tity of sulphite, soda, or cotton-hull fiber. 



Fig. 2. — Rice-straw fibers. Though comparatively' short, these are strong and felt well. 



(Enlarged 71 diameters.) 



Rice straw also yields a food extract which in the analyses thus 

 far made runs rather high in protein ; nevertheless, it does not seem 

 necessar}^ in the case of this waste to depend upon the extract in order 

 to make the material as a whole utilizable. The chief problem arises 

 from the low recovery of soda from the spent liquors of the cooking 

 process, due to the presence of a high percentage of silica in the straw. 



Rice straw^ has a distinct ardvantage over cornstalks in that it is 

 assembled at one place for thrashing and can be baled at once without 

 extra cost for hauling in from the field and shredding. Although it 

 does not promise to give as high a jdeld of fiber as broom-corn stalks, 

 it has a distinct advantage over these because of the greater acreage 

 grown. It has a further advantage over both corn and broom corn 

 in that it is grown rather compactly in restricted areas, so that a pulp 

 or paper mill located in any good rice-growing section could secure its 

 supply of raw material within a comparatively small distance from 

 the mill. Texas, Louisiana, Arkansas, and South Carolina are the 

 great rice-producing States. At present these States have a total of 

 only four paper mills, none of Avhich use this material. 



The number of acres of rice harvested in the United States in 

 1909 was 720,000. Growers state that the yield of straw will run from 

 2 to 2^ tons an acre. Using the lower yield, in the neighborhood of 



^^Thc paper upon ivhicJt tliis page fs printed vafi made from cornatalks. 

 See page 3. 



[Cir. 82] 



