kinds of fertilizer are in com mon use for sugar- beets : green fertilizers, stable manures and chemical or so-called commercial fer tilizers. The green fertilizer most commonly used with sugar-beets is alfalfa. It is becoming more and more common to use alfalfa in a system of ro tation with sugar-beets, plowing the alfalfa under at the end of three or more seasons. A crop of alfalfa may or may not be plowed under, depending on the requirement of the soil for humus. The roots of the alfalfa necessarily furnish more or less humus and should be broken up long enough before beet-seed-planting to allow them to rot, otherwise they will be very troublesome in the cultivation of the young beets. Usually alfalfa sod plowed in the fall is in proper condition for beet seed the follow ing spring, but with some growers it is customary to use another crop in the rotation between the alfalfa and beets. For this purpose potatoes or one of the small grains are generally used. Other green crops are sometimes used in rotation with beets, of which clover, rye or rape are employed when a supply of humus is desired as quickly as possible.
So far as any exact data have been secured,. stable manures give better results with sugar-beets than do commercial fertilizers. While it is true that different kinds of stable manures produce dif ferent results with sugar-beets, the same kind of manure will give even more variable results, de pending on the time of its application and the con ditions under which it was kept previous to using. A good crop has generally been secured by apply ing well-rotted manure just before plowing, and incorporating it thoroughly with the soil.
In regard to commercial fertilizers, the best re sults have generally followed the use of a complete fertilizer, although when a certain element is known to be present in the soil in sufficient quan tity and in an available form, nothing seems to be gained by applying that particular element in the form of a chemical.
The time of applying the commercial fertilizer must be governed by its solubility. If it is ground bone, or other material that dissolves with diffi culty, the best results are secured by applying it long enough before the beets are up to allow the material to begin to break down and become soluble. On the other hand, if the material is easily soluble, as nitrate of soda, the results are more satisfactory if several applications are made at intervals of several weeks. Nitrate of soda has a tendency to prolong the growth of the beets and therefore should not be used very late in the season, as in such case the beets would fail to ripen properly.
The seeds are produced from flowers that occur, for the most part, in groups of two to seven, giving rise to seed-balls which usually con thin as many germs as there were flowers in the cluster. Occasionally a flower stands by itself and
develops a single seed ; in other instances, one or more of the flowers, either singly or in groups, fails to produce seed, thus reducing the num ber of seeds, or the num ber of germs, in the seed-ball. The flowers are five-parted ; that is, there are five stamens and five parts to the corolla. The petals are wanting and the pistil is three-parted. Fig. 817 shows the construction of the beet flower as seen in longitudinal sec tion. The sepals persist and form a part of the seed-coat, giving to the single- germ seeds the form of a five-pointed star. The individual seeds in the seed-balls are made up in the same way, but the star-shape is not so apparent when the seeds are welded to gether in the form of balls. Seed plants are shown in Figs. 818, 819.
Beet plants are biennial, that is, they produce seed the second season. In those countries where the beet is indigenous, the winters are warm enough so that the plants will live over from the first to the second season ; but in most of our com mercial sugar-beet sections it is necessary to pro tect them from frost during the winter. This is usually done by placing them in some form of a silo or pit. One of the common and most satisfac tory methods of pitting consists in piling the beets in the form of a cone or a pyramid on the surface of the ground, having selected for the purpose a well-drained spot. The piles are then covered with straw, which, in turn, is covered with earth; as the temperature falls with the advance of winter, more earth is added to keep the frost from reaching the beets. (Fig. 820.) As soon as the danger of kill ing frosts is over in the spring, the beets are taken from the silo, tested for sugar if they were not tested before pitting, and, if up to the standard or above, are planted for seed production ; but if below the standard, they are discarded.
The sugar test is considered necessary in order to keep the descendants of the seed of the parent beets from deteriorating in quality for successful sugar-making. Fifteen per cent of sugar is usually taken as the standard, although many of the beets planted for seed test much higher. Many other factors enter in to influence the quality, so that from roots possessing a given sugar content there are often secured beets much richer as well as much poorer than the original seed. Beets possess ing a minimum amount of certain salts are also desired for seed, since such salts taken up by the beets are dissolved with the sugar and prevent a part of the sugar from crystallizing in the process of sugar-making. This quality, like the sugar con tent, is influenced by other factors than the quality of the parent.