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But it is now

compared with the many failures. believed that these cultures can be prepared and used so as to be generally effective and without excessive cost to the grower.

In preparing cultures it has been found that by gradually reducing the amount of nitrogen in the culture of media, it is possible to increase the nitrogen fixing power in these germs from five to ten times as much as usually occurs in nature. It is now known that the bacteria thus grown upon nitrogen free media retain high activity if carefully dried and then revived in liquid media at the end of the varying lengths of time. Some absorbent is used to soak up the tubercle-forming organisms. The cultures are then allowed to dry, and when in that condition they can be safely sent to any part of the country without losing their efficacy. It is necessary to revive the dry germs by immersing them in water. By adding certain nutrient salts the bacteria are greatly increased if allowed to stand for a limited time as short, in some instances, as 24 hours. The culture thus sent out in a dry form, and no larger than a yeast cake, may thus be made to furnish bacteria sufficient to inoculate not less than an acre of land. It is stated that the amount of inoculating material thus obtained is only limited by the quantity of the nutrient water solution used in increasing the germs, so that the cost of inoculating land by this process is not large. The culture may be applied by simply soaking the seed in it, by spraying the soil, or by first mixing the culture into earth, spreading it over the field and then harrowing it. Inocu

lations thus tried under the supervision of the United States Department of Agriculture have proved quite successful.

Where any legume is extensively grown surrounding soils come to be inoculated through the agency of winds and water. The increase brought to the yield of plants on various soils runs all the way from a slight gain to 1000-fold. And when soil is once inoculated it remains so for a long time, even though the proper legume should not be grown again on the same soil.

The amount of nitrogen that may thus be brought to many soils by growing clover and other legumes upon them is only hedged in practically by the nature of the rotation fixed upon. An acre of clover when matured will sometimes add 200 to 300 pounds of nitrogen to the soil under favorable conditions. Where the soil contains the requisite bacteria, the young plants begin to form tubercles when but a few weeks old, and continue to do so while the plant is active until mature. That the plants use much of the nitrogen while growing would seem to be clear, from the fact that toward the close of the growing season the tubercles become more or less broken down and shrunken.

CHAPTER III

MEDIUM RED CLOVER

Medium Red Clover (Trifolium pratense) is also known by the names Common Red Clover, BroadLeaved Clover and Meadow Trefoil. The term medium has doubtless come to be applied to it because the plants are in size intermediate between the Mammoth variety (Trifolium magnum) and the smaller varieties, as the Alsike (Trifolium hybridum) and the small white (Trifolium repens). But by no designation is it so frequently referred to as that of Red Clover.

This plant is spreading and upright in its habit of growth. Several branches rise up from the crown of each plant, and these in turn frequently become branched more or less in their upward growth. The heads which produce the flowers are nearly globular in shape, inclining to ovate, and average about one inch in diameter. Each plant contains several heads, and frequently a large number when the growth is not too crowded. When in full flower these are of a beautiful purple crimson, hence, a field of luxuriant red clover is beautiful to look upon. The stems of the plants are slightly hairy, and ordinarily they stand at least fairly erect and reach the height of about one foot or more; but when the growth is rank, they will grow much

higher, even as high as 4 feet in some instances, but when they grow much higher than the average given, the crop usually lodges. The leaves are numerous, and many of them have very frequently, if not, indeed, always, a whitish mark in the center, resembling a horseshoe. The tap roots go down deeply into the soil. Usually they penetrate the same to about 2 feet, but in some instances, as when subsoils are open and well stored with accessible food, they go down to the depth of 5 or 6 feet. The tap roots are numerously branched, and the branches extend in all directions. When they are short, as they must needs be in very stiff subsoils and on thin land underlaid with hard soil, the branches become about as large as the tap roots. It has been computed that the weight of the roots in the soil is about equal to the weight of the stem and leaves.

Medium red clover is ordinarily biennial in its habit of growth, but under some conditions it is perennial. Usually in much of the Mississippi basin it is biennial, especially on prairie soils. On the clay loam soils of Ontario, Ohio, Michigan, Wisconsin, Indiana and some other States, it is essentially biennial, but many of the plants will survive for a longer period. In the mountain valleys in the Northwestern States, and on the Pacific slope west of the Cascade Mountains, it is perennial. Medium red clover meadows in these have been cut for several successive years without re-seeding the crop. The duration of this plant is also more or less influenced by pasturing as compared with cutting for seed. Grazing the plants has the effect of prolong

ing the period of their growth, while maturing seed from them has the opposite effect.

Medium red clover is characterized by a rapid growth. Seed sown in the spring has in certain climates produced a crop of hay in 120 days from the date of sowing. It is also most persistent in its growth from spring until fall when sufficient moisture is present. In this property it far outranks any of the other varieties of clover. It comes into bloom in the South during the latter half of May and in the North during the month of June, early or later, according to location, and in about sixty days from the time that it is cut for hay. Ordinarily, a second cutting of hay may be taken from it and still later some pasture.

It furnishes excellent pasture, soiling food and hay for nearly all classes of live stock. While it is much relished by the stock, it is probably not exceeded in its capacity for quick and prolonged growth throughout the growing season by any pasture plant, except alfalfa. For a similar reason it stands high as a soiling food. No other variety of clover grown in America will furnish as much of either pasture or soiling food. For animals producing milk and for young animals, the pasture is particularly excellent. It is also the standard pasture for swine where it can be grown, and where alfalfa is not a staple crop. When the hay is well cured, it makes a ration in even balance for cattle and sheep, and for horses it is equally good. The prejudice which exists in some quarters against feeding it to horses has arisen, in part, at least, from

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