A much larger acreage of sweet clover is grown in northern Illinois than in any other of the eastern North-Central States. The conditions in the western North-Central States and in the Mountain States appear to be particularly adapted to this crop. It is in that part of the country that the largest acreage is found, and, with the exception of the limestone regions of the South, that the least difficulty is experienced in obtaining a stand.
In those parts of the Mountain and Pacific Coast States, especially Utah, where it has not been tested carefully or where red clover or alfalfa can be grown successfully, sweet clover is looked upon as a weed. It may rightly be considered a weed in the irrigated regions of the West and Northwest, where it grows luxuriantly on ditch Banks. The dissemination of this plant in all parts of the country has been hastened by beekeepers who have seeded it in waste places for the production of honey.
Sweet clover is adapted to a wider range of climatic conditions than any of the true clovers and possibly alfalfa; in fact, it may be grown successfully in any portion of the United States except, perhaps, Florida, and in Florida trials with biennial yellow sweet clover, annual sweet clover, and Melilotus suaveolens have been successful. Apparently neither the high temperatures of the South nor the cold winters of the North severely affect the plants, provided there is sufficient moisture in the soil. Comparatively little winterkilling is experienced in Montana, Wyoming, Idaho, and North Dakota when the seed is sown in close drills or broadcasted. Although approximately 50 per cent of the sweet clover seeded in rows 3 feet apart at Moccasin, Mont., was killed by the unusually severe winter of 1915-16, no winterkilling was noted in plats seeded in close drills.
Sweet clover thrives in the more humid parts of the country, as well as in the semiarid regions where the rainfall is but three-fifths of that required for the normal growth of such crops as red clover and timothy. In the semiarid regions of the West sweet clover has proved to be somewhat more drought resistant than alfalfa.
[REQUIREMENTS FOR OBTAINING A STAND.]
The requirements for obtaining a stand of sweet clover are somewhat exacting. It is for this reason that so many failures have been experienced. It must not be assumed, because sweet clover is found growing luxuriantly in many waste places and on uncultivated land, that a stand may be obtained by planting it at any time of the year, in any manner, and under all conditions. Throughout the eastern and southern portions of the country, with the exception of a few regions rich in limestone, much care must be used in the preparation of the seed bed, the selection of seed, and the manner of seeding if success is to be expected. For this reason it is necessary to understand fully the requirements for obtaining and maintaining a successful stand.