Clover seed is seldom clean. Besides dirt, weed seeds are found in greater or less abundance ; the cheaper grades of clover seed frequently contain enormous quantities, amounting to 80 or 90 per cent. Old seed or weathered seed does not germi nate well. Green-colored seeds make weak plants. The vigor of germination of brown seeds decreases rather regularly from light brown to dark brown or black. The presence of any large quantity of brown or black seeds indicates low grade. Alsike and timothy seed are rather generally found in red clover seed, and, while not injurious, lower the grade. Farmers should buy their clover seed con siderably in advance of the time it is needed for sowing, and examine it for purity and germinating power. The United States Department of Agricul tare and many of the state experiment stations will also examine the seed free of charge if requested. Adulterated clover seed is the chief source of new weeds on the farm.
Seeding.
In growing clover for seed, sow clean seed on clean land. Upland soil of only medium fertility gives the best results. The crop is seeded either alone or with grain, as is usual for hay, but must not be mixed with other grass seed. Eight to fifteen pounds of clean seed per acre should be used, de pending on the size of the seed and its percentage germination.
Harvesting.
The first crop is usually cut for hay in most clover-growing sections, and the second crop of the same season cut for seed. If the first crop is left for seed, new growth springs up before the first plants mature. The plants which mature first fall down, producing a tangled mass, the field remains in bloom six to eight weeks instead of twenty or thirty days, and the results are generally very un satisfactory. These remarks apply particularly to the first year. They do not apply when the field is grazed or cut back about the middle of June. In a few sections, as northern Michigan, which has lately become an important clover seed section, the first crop of each season is the one used for seed. The second crop there matures too late for seed. The yield secured from the firstcrop averages close to six bushels per acre, and one instance of twelve bushels per acre from mammoth red clover has been reported. A. D. Hopkins states that in West Virginia the first crop is as well filled with seed as the second.
Another reason in most sections for using the second crop of the season for seed is that if it does not fill well with seed, the first hay crop has paid for the use of the land.
Again, bumble-bees and other insects which are believed to be essential for the cross-fertilization of clover flowers and the production of seed, are more abundant late in the summer than during the period when the first crop is in bloom. Darwin first
pointed out the relationship between bees and clover seed. He covered 100 heads with matting. These produced no seed, while 100 heads exposed to insect visits produced 2,700 seed. A very large number of pollen-collecting insects work on red clover and effect cross-fertilization, but bumble bees are the most frequent visitors. It is still an open question whether or not red clover is self fertile. Experiments in England by Garton and in the United States by W. J. Beal and by the writer seem to indicate that it is in part at least self-fertile.
It is often a question whether to cut the crop for hay or to save it for seed. The hay is certain ; the seed-crop speculative. If left for seed the crop is spoiled for hay. As a rule, if the heads selected at random contain twenty-five to thirty seeds each, it will pay to save the crop for seed. In a test by the writer, twenty- five heads gathered from a twenty-acre field of first-crop clover averaged twenty-three seeds per head. This field yielded two bushels of seed per acre. Twenty-five heads from a seven-acre field of first-crop clover alongside aver aged fifty-three seeds per head and the yield was eight bushels per acre. With mammoth red clover, seed-growers generally pasture off or clip black the first crop about the middle of June. This retards the crop and gives a more uniform bloom, the straw is reduced and the yield of seed generally increased. In most cases, this practice gives the best results with June clover when the first crop is saved for seed.
Clover is ready to cut when the heads are brown and the seeds shell out plump and hard. Alsike clover should be cut even before all the heads are fully ripe, as it shells out much more readily than red clover. Either a mower or reaper may be used for cutting. In tangled clover the mower is best, while with the reaper less raking is required. When possible, clover is hulled directly from the field. This is particularly desirable with red clover, which is bulky to handle. The danger of a long wet period at hulling time makes leaving in the field precarious ; the wise farmer will provide some shelter for his crop rather than run this risk. Clover should be hauled in a rack with a tight bottom, particularly alsike. As the seed comes from the huller it is mixed with more or less dirt and foreign seeds and should he recleaned before marketing. It is usually sold by sample.