The characteristics which they possess in common are the high protein content found in them, the marked palatability of the pasture and hay, unless in the sweet and burr varieties, the power which they have to enrich and otherwise improve soils, and the honey which they furnish.
Plan of Discussion.—Chapter I., that is, the present chapter, as already indicated, is introductory, and outlines the nature, scope and plan of the work. Chapter II. deals with the general principles and facts which relate to the growing of clovers. A close study of these will, in the judgment of the author, prove helpful to those who engage in growing any of the varieties of clover discussed in the book. Chapters III. to XI. inclusive treat of individual varieties, a chapter being devoted to each variety. It has been the aim of the author to discuss them in the order of the relative importance which they bear to the whole country and to devote space to them accordingly.
The following varieties are discussed and in the order named: Medium Red clover, Alfalfa, Alsike, Mammoth, Crimson, Small White, Japan, Burr and Sweet. All of these varieties will be found worthy of more or less attention on the part of the husbandmen in the various parts of this continent.
Chapter XII. is devoted to a brief discussion of miscellaneous varieties which have as yet been but little grown in this country, or of varieties of but local interest. The former are Sainfoin (Onobrychis sativa), Egyptian clover (Trifolium Alexandrianum), yellow clover (Medicago lupulina), Sand Lucerne (Medicago media), and a newly introduced variety of Japanese clover (Lespedeza bicolor). These may prove more or less valuable to the agriculture of the United States when they have been duly tested, a work which as yet has been done only in the most limited way. The latter include Florida clover (Desmodium tortuosum), more frequently called Beggar Weed, Buffalo clover (Trifolium reflexum), and Seaside clover (Trifolium invulneratum). These may be worthy of some attention in limited areas where the conditions are favorable, but it is not likely that they will ever be very generally grown. They are dwelt upon rather to show their small economic importance and with a view to prevent needless experimentation with plants possessed of so little real merit.
CHAPTER II
SOME GENERAL PRINCIPLES WHICH APPLY TO THE GROWING OF CLOVERS
In growing clovers, as in growing other crops of the same species, which embrace several varieties, certain features of management will apply more or less to all of these in common. It will be the aim to point out the chief of these in the present chapter.
Adaptation in Clovers.—Adaptation in the varieties of clover considered will be more fully given when discussing these individually, but enough will be said here to facilitate comparisons. Clover in one or the other of its varieties can be grown in almost all parts of the United States and Canada. Speaking in a general way, the medium and mammoth varieties can be grown at their best between parallels 37° and 49° north latitude. Alfalfa has special adaptation for mountain valleys of the entire West, but it will also grow in good form in parts of all, or nearly all, the other States. Alsike clover grows in about the same areas as the common and mammoth varieties, but it may also be grown further North, owing to its greater hardihood. Crimson clover has highest adaptation to the States east of the Allegheny Mountains and west of the Cascades, but will also grow in the more Central States south, in which moisture is abundant. Small white clover will grow in any part of the United States or Canada in which moisture is sufficiently present. Japan and burr clover grow best south of parallel 37° and east of longitude 98°. Sweet clover will grow in all the States and provinces of the United States and Canada, but has highest adaptation for the Central and Southern States.
With reference to adaptation to soils, medium and mammoth clover grow best on upland clay loam soils, such as have sustained a growth of hardwood timber, and on the volcanic ash soils of the Western mountain valley. Alfalfa flourishes best on those mountain valley soils when irrigated, or when these are so underlaid with water as to furnish the plants with moisture. Alsike clover has much the same adaptation to soils as the medium and mammoth varieties, but will grow better than these on low-lying soils well stored with humus. Crimson clover has highest adaptation for sandy loam soils into which the roots can penetrate easily. Small, white clover has adaptation for soils very similar to that of alsike clover. Japan clover and burr clover will grow on almost any kind of soil, but on good soils the growth will, of course, be much more vigorous than on poor soils. Sweet clover seems to grow about equally well on sandy loams and clay loams, but it has also much power to grow in stiff clays and even in infertile sands.