=Renewing.=--Since this plant is an annual, it cannot be renewed in the sense in which renewal is possible with a perennial. But as has been shown above (see page 294), it may be grown annually for an indefinite period in the same land and without re-sowing by hand. It has also been shown that by sowing the seed in certain crops at the proper season, from year to year, it may be made to grow from year to year where the rotation will admit of this. (See page 295.) When the ground is well stored with seed, the plants will continue to come up freely in the soil for at least two or three years, even without any re-seeding of the land. =As a Fertilizer.=--The growing of burr clover exercises a beneficial influence on the land. Its value for this purpose, since it can be grown as a catch crop, is probably greater than its value in providing food for stock. Like all plants that are more or less creeping in their habit of growth, it shades the soil and keeps it moist, which, in conjunction with the influence of the roots, puts it in a friable condition. When the plants grow rankly, it is not easy to bury them properly with the ordinary plow, but in such instances, if cut up with a disk harrow, the work is facilitated. The plants quickly die down so as to make plowing easily possible, but the aim should be to have such decay take place within the soil rather than above it. CHAPTER XI SWEET CLOVER Sweet clover is so named from the sweet odor which emanates from the living plants. It is of two species. These are designated, respectively, _Melilotus alba_ and _Melilotus officinalis_. The former is also called Bokhara clover, White Melilot and Tree clover. It is possibly more widely known by the name Bokhara than by any other designation. The latter is sometimes called Yellow clover. The difference between these in appearance and habits of growth does not seem to be very marked, except that the blossoms of the former are white and those of the latter are yellow. Sweet clover is upright and branched in its habit of growth. It attains to a height of from 2 to 8 feet, according to the soil in which the plants grow. The somewhat small and truncate leaves are not so numerous, relatively, as with some other varieties of clover, and the stems are woody in character, especially as they grow older. The blossoms are small and white or yellow, according to the variety, and the seed pods are black when ripe. The roots are large and more or less branched, and go down to a great depth in the soil; especially is this true of the main, or tap root.