Success has not attended efforts to grow alfalfa in all parts of New York. This is due to two principal reasons: (1) farmers have not known the plant and its habits well enough to give it the care and treatment it demands; (2) the soils of many localities, because of their physical condition or composition, are not suitable for the plant.
The alfalfa seedling is not a strong plant. It cannot compete with weeds nor overcome adverse conditions of moisture; it cannot adapt itself to conditions resulting from poor preparation of land, and it is not vigorous in its ability to get food from any source. Care must be given to the preparation of the land in order that sufficient moisture may be supplied during the early stages of growth and that there may be an abundance of quickly available plant-food. After growth has started, alfalfa has the power to get some of its nitrogen from the air through the nodules which grow upon its roots; yet during the early stages of growth it is essential that the soil be supplied with all elements of plant-food in available form.
While alfalfa requires an abundance of moisture for its best growth and development, yet it will not grow in soils that hold water for any considerable length of time. Such soils are usually those with an impervious subsoil or hard-pan, or those of clay or silt structure which retain free water to the exclusion of air. Therefore, it is important that alfalfa soils be well and uniformly drained, either by natural conditions or by underground drains. One other essential of prime importance is that the soil be neutral or alkaline in its reaction; in other words, that it contain no free acid. Limestone or blue-grass soils are ideal in this regard for alfalfa. If acid is present, the difficulty may be corrected either wholly or in part by the application of 500 to 2,000 pounds of lime per acre.
As in most other legumes (members of the family Leguminosæ, including peas, beans, clovers), there is a peculiar relationship existing between the plant and excrescences or nodules upon its roots. These nodules are essential to the normal growth and development of the plant. They contain bacteria, and these bacteria have the power of "fixing" or appropriating the free atmospheric nitrogen in the soil. Legumes are "nitrogen-gatherers," whereas most other plants secure their nitrogen only from decomposing organic matter. Failure to have the soil inoculated with the proper bacteria for alfalfa is the cause for many failures with the crop. In most instances when the plants do not make satisfactory growth, or have a yellow, dwarfed appearance, the trouble can be traced to the absence of these bacteria from the soil, and hence to a lack of nodules on the roots. The relationship existing between the plant and the organism is one of mutual benefit. Each kind of leguminous plant seems to have its characteristic bacterium, which grows on no other plant, although this question is not thoroughly settled.
Farmers are becoming aware of this requisite in alfalfa culture and usually supply it in two different ways. The older method is to take the surface soil from an old alfalfa field, where the plants have grown well and where nodules are to be found on the roots, and to sow it on the land to be seeded at the rate of one hundred or more pounds per acre. In this way the soil becomes inoculated with the bacteria, and as the young plants spring into growth the bacteria develop on the roots. Another method is to inoculate the seed before sowing with artificial cultures of the bacteria. Both of these methods are usually successful, and if soil conditions are right the chances for failure are few.
Alfalfa should be cut when it opens into flower. At this time the stems and leaves contain their highest percentage of nutrients, the leaves do not so easily fall off in curing, and the stems are not so woody. Besides these reasons, if cutting be delayed until after flowering, the plant may not spring quickly into subsequent growth.
Disease does not spare the alfalfa plant. Both leaves and roots are attacked, the leaf spot being serious. The parasitic dodder is a serious enemy in some parts of New York State.