Part 4
The ability of sweet clover to reclaim abandoned, run-down land has been demonstrated in northern Kentucky and in Alabama. In these regions many farms were so depleted in nitrogen and humus by continuous cropping with nonleguminous crops that profitable yields could be obtained no longer, Through the use of this crop many of these farms have been brought back to a fair state of fertility. Tests at the Alabama Agricultural Experiment Station show that the increased yield of corn following sweet clover which had occupied the land for two years was 6-3/4 bushels per acre. The cotton grown on the land the second year showed an increase of 56 pounds per acre. The combined value of the increased yields of corn and cotton for the two years was estimated at $9.75. The total yield of hay for the two preceding years was 6.8 tons per acre. In another experiment at this station cotton was planted on land that had grown sweet clover the two previous years and on land that had received an application of 18 tons of stable manure per acre. The sweet-clover plat produced 280 pounds of seed cotton the first year and 120 pounds of seed cotton the second year more than the plat which received the heavy application of manure.
Land on which sweet clover had been grown for four years at the Ohio Agricultural Experiment Station yielded 26.9 bushels of wheat per acre as compared with 18.6 bushels on the check plat. Sweet clover was seeded at the Tennessee Agricultural Experiment Station in the spring of 1912. One cutting of hay was removed that year and the following spring the field was plowed and planted to corn. The corn yielded 58.8 bushels per acre as compared with 41.1 bushels per acre for an adjoining plat where rye was turned under. A number of tests have been conducted in southeastern Kansas which show clearly the value of sweet clover as a soil-improving crop for that section. The yield of wheat has been increased as much as 7 bushels per acre and that of corn as much as 22 bushels per acre by plowing under the second-year growth of clover.
Annual yellow sweet clover is rapidly gaining in favor as a green-manure crop for orchards in the Southwest. In Arizona two plats seeded in October and plowed under in April yielded, respectively, 16 and 17 tons of green matter to the acre. At the Arizona Agricultural Experiment Station annual yellow sweet clover, lupines, and alfalfa were tested as green-manure crops for orchards. In this experiment the sweet clover clearly showed its superiority to lupines or alfalfa for this purpose, as it yielded from 21 to 26 tons of green matter per acre, whereas the highest yield for the lupines was 10 tons and for the alfalfa 15 tons per acre.
The use of annual sweet clover as a green-manure crop in southern California has increased very rapidly in recent years, and this increased use apparently has been justified by the results obtained with it. One of the most interesting green-manure tests thus far noted was conducted at the California Citrus Experiment Station. In this experiment nine legume plats and eight nonlegume plats alternated with each other. The 4-year average weight of green matter produced on the sweet-clover plat was 14-3/4 tons per acre, whereas the 5-year average weight of green matter produced by common vetch and Canada field peas was 12 tons and 9 tons, respectively, per acre. On one series of these plats corn was planted in rotation with the clover. The average yield of shelled corn for four years was 46 bushels to the acre on the sweet-clover plat, as compared with 35 bushels to the acre on the common-vetch plat and 40 bushels per acre on the field-pea plat. One barley plat receiving each year an application of 1,080 pounds of nitrate of soda gave an average yield of 41 bushels per acre. The 2-year average yield of potatoes following sweet clover was 252 bushels per acre, as compared with 171 bushels following common vetch and 234 bushels following field peas. Sweet clover has proved to be an excellent plant to grow in rotation with sugar beets, as the 2-year average for the beets following it was 19.8 tons per acre, as compared with 15.3 tons following common vetch, and 17.6 tons following field peas.
Annual yellow sweet clover makes a profitable growth only in the South and Southwest and therefore should not be planted in any other section of the country.
In those sections of the United States where the soils are low in humus it is to be strongly recommended that sweet clover be grown for green manure. This method is being practiced in some sections of the country with excellent results.
It should be remembered that sweet clover will not make a satisfactory growth on acid soils and that it is very essential to provide inoculation if the soil is not inoculated already.
SWEET CLOVER IN ROTATIONS.
As sweet clover is a biennial plant, it lends itself readily to short rotations. It may be seeded in the spring on winter grain or with spring grain, the same as red clover. It will produce at least as much pasturage the following fall as red clover, and in some parts of the country a cutting of hay may be obtained after the grain harvest. The following year the plants will produce two cuttings of hay or one cutting of hay and a seed crop. In some sections of the United States this plant is replacing red clover in rotations, as it will succeed on poorer soils than red clover and will add much more humus to the soil. It will withstand drought better than either red clover or alfalfa, and on this account its use in rotations may be extended into drier sections. As a rule the beneficial effect of sweet clover on the subsequent crops is more marked than that of other legumes. This is especially true with corn, and whenever possible corn should follow sweet clover in rotations. Root crops also are benefited by its use in rotations, as the large deep roots of sweet clover open up the soil.
SWEET CLOVER AS A HONEY PLANT.
A number of the leading honey plants fail to secrete nectar in part of the territory in which they are found, but white sweet clover ranks as a valuable source of nectar wherever found in sufficient quantity in the United States. The period of nectar secretion usually follows that of white and alsike clovers in the Northern States, and consequently comes at a time when the colonies are strong enough to get the full benefit of the secretion. The honey from white sweet clover is light in color, with a slight green tint, the flavor being mild and suggestive of vanilla. The characteristic flavor and color of the honey seem to be less marked during a rapid secretion of nectar, In the irrigated portions of the West honey from white sweet clover is often mixed with that from alfalfa.
Beekeepers have long recognized the value of sweet clover as a source of nectar, and for years tons of seed have been sold annually by dealers in beekeepers' supplies. It has never been found profitable to cultivate any plant solely for nectar, and those beekeepers who were primarily interested in the plant for bee forage have scattered the seed chiefly in waste places and along railroad embankments and roadsides. A number of beekeepers who were also engaged in general farming have for years utilized the plant for forage, and they were among the earliest to grow the plant for seed, so as to be able to supply their fellow beekeepers. Sweet clover to-day is almost the only plant which beekeepers seek to increase in waste lands in their localities.
The yield of nectar from sweet clover is heavy, and a number of beekeepers now market this honey in carload lots. Sweet clover is utilized for honey especially in Kentucky, in Iowa, and in Colorado and adjacent States. In Alabama and Mississippi a number of beekeepers are harvesting large crops chiefly from this source. The color and flavor make this plant suitable for either comb or extracted honey.
Yellow sweet clover is perhaps as valuable for nectar as white sweet clover, but beekeepers have paid less attention to it. This is probably due to the fact that the blooming period of the yellow species often coincides with that of white and alsike clover, making it less valuable to the beekeeper. In sections where the quantity of white and alsike clover is limited and it is desired to plant sweet clover for bee pasturage, a mixture of the white and yellow species is recommended, as the yellow species will bloom from 10 to 14 days earlier than the white.
Wherever any of the species of sweet clover are cultivated, either for forage or for seed, beekeeping is to be recommended as a valuable source of additional income, and such locations are especially suitable for extensive commercial beekeeping.
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Transcriber Note
Minor typos may have been corrected. Illustrations may have been moved to avoid splitting paragraphs. Many of the Tables have labels which are displayed as italics; but due to space limitations in the text-only version, the italicization was ignored.
End of Project Gutenberg's USDA Farmers' Bulletin No. 820, by H. S. Coe