Clarification.— The sorghum juice as it comes from the mill contains about 25 per cent of im purities of various kinds. This material must be removed by clarification in order to secure syrup of high quality. Some of the impurities rise to the surface when the juice is heated and may be removed by skimming ; others settle to the bottom of the pan and may be removed by drawing off the juice from above, leaving the sediment undisturbed. Filtering aids in removing foreign material, while the addition of some substance, such as milk, which coagulates on heating and rises to the surface, carrying with it some of the suspended matter, is used to remove others. The substance most used for this purpose, however, is dry medium-grained clay, using about ten pounds of clay to fifty gallons of juice. The particles of clay on settling to the bottom of the pan carry with them much of the impurity suspended in the juice. The clay may be added to the juice either before or after heating. Liming to neutralize the natural acids in the syrup is sometimes practiced. The processes most frequently employed are skimming, settling and claying.
Making the syrup.—The juice is reduced to syrup by heating, the water being driven off by evapora tion. Shallow pans are used for this purpose, the juice usually being about three inches deep in the pans. The evaporation should be rapid and the juice should be cooled quickly after evaporation. Six to eight gallons of juice are required to make one gallon of syrup, which weighs about eleven and one-half pounds. The molasses, after being reduced to the proper density, may be stored in barrels or put up in tin cans. Its salability in most markets is greatly increased if the packages con taining it are attractively labeled. The average production of syrup to the acre is fifty-eight gal lons, though this yield is greatly exceeded under favorable conditions.
Sugar production.—The production of sugar from sorghum has never been practiced commercially, though it has been found possible to make sugar of good quality from this plant. Until a strain
of greater sugar content than we now have is developed and improved methods of handling the juice are perfected, little sugar will be made from this crop.
Selecting and storing the seed.
While the great bulk of the seed planted is not selected at all, yet the time required to select seed-heads from stalks having desirable charac teristics is comparatively slight, and when only a few acres are grown the yield and quality of the crop can be materially increased with little trou ble. When the crop is grown on a large scale it is a good plan to select seed enough to plant a few acres and use the progeny of this selected seed for planting the main crop the ensuing year.
The heads should be removed when fully ripe ; after they are well cured they may be threshed, or stored without threshing. In either case the seed should be kept in a dry place where it will not heat or mold. In the South it is often necessary to store in a tight box and treat with carbon bi sulfid or some other insecticide to prevent the de struction of the seed by weevils. The seed weighs fifty to sixty pounds per bushel, according to the proportion of hulls.
The sorghums are not often seriously affected by insects or diseases. Chinch-bugs sometimes cause trouble, especially when they migrate from adjoining grain-fields. In some sections of the South the green aphis attacks the growing parts of the plants, but usually little damage is done. Remedial measures are seldom necessary, other than the avoidance of continuous cropping with the sorghums on any given piece of land.
The grain smut of sorghum (Phacelotheca diplo sp)ra) and the whole-head smut (Phacelotheca rei liana) attack the plants, but the resulting damage is usually comparatively slight. Both smuts can he kept in check by rotation and by selecting the seed; the grain smut can be further held in check by treating the seed with hot water, formalin, or any of the other well-known smut remedies.. [See Index.]