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feeding it when improperly harvested, when overripe, when damaged by rain, or by overcuring in the sun, or when it may have been stored so green as to induce molding. It may also be fed with much advantage to brood sows and other swine in winter.

As a soil improver, medium red clover is probably without a rival, unless it be in mammoth clover, and in one respect it exceeds the mammoth variety; that is, in the more prolonged season, during which it may be plowed under as a green manure. Its quick growth peculiarly adap's it to soil enrichment. For this reason, it is more sown than any of the other varieties in the spring of the year, along with the small cereal grains to be plowed under in the late autumn or in the following spring, after the clover has made a vigorous start, since it produces two crops in one season, the first crop may be harvested and the second plowed under after having made a full growth. This can be said of no other variety of clover. More enrichment is also obtained from the falling of the leaves when two crops are grown than from the other varieties.

The influence of this plant on weed destruction when grown for hay is greater than with the other varieties of clover. This is owing in part to the shade resulting from its rapid growth and in part to the two cuttings which are usually made of the crop. These two cuttings prevent the maturing of the seeds in nearly all annual weeds, and to a very great extent in all classes of biennials. The power of this crop to smother out perennials is also considerable, and when this is linked with the weakening

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Fig. 2. Medium Red Clover (Trifolium pratense)

Oregon Experiment Station

caused by the two cuttings, it sometimes proves effective in completely eradicating for the time being this class of weeds.

Distribution.—Medium red clover is thought to be native to Europe. It was probably introduced into England some time early in the seventeenth century. That it was attracting attention about the middle of the century or a little later, is rendered probable by the fact that it is discussed at considerable length in the third edition of Blyth's "Improver Improved,” published in 1662, while it is not mentioned in the first edition, published in 1650. It was doub:less introduced into the United States by the early colonists and at sundry times.

Medium red clover will grow in good form only in the temperate zone, since it cannot stand excessive heat or excessive cold. The northerly limit of its successful growth in North America is somewhere about 50° north lati' ude on the wind-swept prairies, but on suitable soils, and protected somewhat by trees and winter snows, it will probably grow 10 degrees further to the north. In British Columbia, on the Pacific slope, it will probably grow as far north as Alaska. But on prairies eas-ward from the Rocky Mountains, it has not been grown with much success much further north than 48°, unless under the eastern shadow of the Rocky Mountains, Low temperatures in winter, where there is only a moderate covering of snow, are far less fatal ‘o clover plants than exposure to the sweep of the cold winds. Even where the thermometer is not so low as in the areas just referred to, such winds are par

ticularly damaging to the plants when they blow fiercely just after a thaw which has removed a previous covering of snow. In some instances, one cold wave under the conditions named has proved fatal to promising crops of clover over extended areas.

In a general way, the southerly limit of vigorous and reliable growth may be put at about 37o. But in some localities good crops may be grown further South, especially in some parts of Tennessee. Nor would it be correct to say that medium red clover grows at its best in many localities much south of 38°. On the plateaus it can be grown further South, where the soil is suitable.

This plant flourishes best in a moist climate. In fact, the abundance and continuance of the growth for the season are largely dependent on the amount of the precipitation, and on the distribution of the same throughout the season. In climates in which it is usual for a long spell of dry weather to occur in mid-summer, the plants will not make rapid growth after the first cutting of the season; but under conditions the opposite, they will grow cone tinuously from spring until fall. Continuous growth may be secured through all the season on irrigated land. Although the plants root deeply, they will succumb under drought beyond a certain degree, and in some soils the end comes much more quickly than on others; on porous and sandy soils, it comes much sooner than on clays. On the latter, drought must be excessive to destroy clover plants that have been well rooted. White clover can withstand much heat when

supplied with moisture. Moderate temperatures are much more favorable to its growth.

Spring weather, characterized by prolonged periods of alternate freezing and thawing, is disastrous to the plants on dry soils, possessed of an excess of moisture, when not covered with snow. They are gradually drawn up out of the soil and left to die on the surface. In some instances, the destruction of an otherwise fine stand is complete. In other instances, it is partial, and when it is, a heavy roller run over the land is helpful in firming the soil around the roots that have been thus disturbed.

Medium red clover can be grown with some success in certain parts of almost every State in the Union. But in paying crops it is not much grown south of parallel 37°. With irrigation it grows most vigorously in the mountain valleys between the Rocky and Cascade mountains, and between about 37° and 50° north latitude. In these valleys its habit of growth is perennial. Without irrigation, the highest adaptation, all things considered, is found in Washington and Oregon, west of the Cascades, except where shallow soils lying on gravels exist. East of the moun'ains, the best crops are in the States of Michigan, Ohio, Indiana, Kentucky, Illinois, Missouri, Iowa, Wisconsin and Minnesota. The soils of Northern Minnesota, Wisconsin and Michigan, that have produced hardwood timber, have unusually high adaptation to the growth of this plant, and as the snow usually covers the ground in these areas in winter, the crop may be relied upon with much certainty. But on the sandy soils, which

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