Soils.—Japan clover is adapted to a wide range of soils. There would seem to be a concensus of opinion in the Southern States that it will grow on almost any kind of soil. It has grown well on hard, stiff clays, both white and red; on sandy levels; on gravelly undulations and slopes; on the banks and in the bottom of gullies; on soils too poor to produce other crops, as on denuded hills and also in groves. But it will grow much better, of course, on good, rich land, as on moist loams and rich alluvial soils. While it prefers moist situations, it is not well adapted to saturated lands. There is no useful pasture plant in the South that would seem so well able to fight its own battle unaided on poor soils as Japan clover, nor is there any which has brought so much of renovation to these for the labor involved.
Place in the Rotation.—Japan clover can scarcely be classed as a rotation plant in the strict sense of the term, since it more frequently comes into the fields, as it were, spontaneously, and owing to the uncommon degree to which it has the power of re-seeding itself, it is frequently grown and grazed for successive years on the land upon which it has been allowed thus to grow. Nevertheless, since it is a nitrogen gatherer, when it has fertilized the land sufficiently by bringing to it a supply of nitrogen and by putting humus into it, crops should follow such as require much of growth to grow them in best form. Such are cotton, corn and the small cereal grains. Owing to its power to grow on worn and even on abandoned soils, and to crowd weeds that grow on them, on such soils it comes in between the cessation of cultivation and the resumption of the same. It frequently grows as a volunteer crop along with Johnson grass, and where it comes, it tends to crowd grasses of but little value, as brown sage.
Where pasture is desired winter and summer, it should be quite possible in some localities to obtain it by sowing such crops annually, as winter oats and sand vetches (Vicia villosa) every autumn, and the seed of Japan clover on the same. The crops first named would provide winter and spring grazing, and the clover, summer and autumn grazing. The clovers and the vetches would both aid in fertilizing the land.
Preparing the Soil.—While careful preparation of the land will result in more certain and uniform germination in the seed, and more rapid growth in the plants, careful preparation of the seed is not so necessary with Japan clover as with many other pasture and hay plants. The seeds are strong in germinating power and the plants are much able to grow, even under adverse conditions, when they do germinate. Usually, the preparation which is suited to nurse crops, amid which this clover is sown, will be suited also to the clover when it is sown thus.
In many instances, however, it is allowed to re-seed itself where it has been once sown, or even where it may have come into the soil without sowing. In this way successive pasture crops have been obtained. But usually where hay crops are wanted, it will prove more satisfactory, all things considered, to sow the seed.
In many instances, simply scarifying the ground has been found a sufficient preparation for the seed. Any implement that will pulverize the surface for a few inches downward will answer for such work. In very many instances, seed, of course, self-sown has become rooted and grown vigorously on unplowed land.
Sowing.—Japan clover is more commonly sown in the spring, but it is sometimes sown in the autumn. There is more or less of hazard in sowing it in the autumn north of the Gulf States, since when the plants are young they will not stand much frost. For the same reason, there is the element of hazard in sowing it too early in the spring. Spring sowing stands highest in favor, taking the whole area into account, in which the clover is grown. While it is possible to sow the seed too early in the spring, it will be readily apparent that the earlier it may be sown without hazard to the young plants, the better will be the returns, because of the growth secured before the advent of dry weather.
The seed may be sown by any of the methods adopted when sowing medium red clover. (See [page 78].) The method which is most labor-saving, however, when sown with a nurse crop, is that which sows it with an attachment to the grain drill used in sowing the nurse crop. If allowed to fall in front of the drill tubes, it will not usually need any other covering than that furnished by the drill tubes followed by the roller.
It may be sown with any of the small cereals, whether these are grown for pasture, for hay, or for grain. When these are fall sown and the clover seed is not sown until the spring, it will be well worth while, when the weather and soil will admit of it, to cover the seed with the harrow. It may also be advisable to sow the seed in pastures, as, for instance, along with orchard grass, or with tall oat grass, as it would tend to fill the vacancies in the land.
When sown alone, 10 pounds of seed per acre will usually suffice. But where there is much seed in the land that has been self-sown, a less quantity will suffice. Where hay crops are wanted from year to year on the same land, it may be obtained by simply disking the land and re-sowing. If the hay is allowed to approach maturity before being cut, sufficient seed will fall to re-sow the land for the next year's crop, but the quality of hay so ripe is not so good as if cut earlier. In pastures, the grazing must not be too close when self-seeding is wanted.