Home Nature-Study Course. 373 



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 upon the 

 roots. The relationship existing between the plant and the organ- 

 ism is one of mutual benefit. Each kind of leguminous plant usually 

 has its characteristic bacterium, which grows on no other plant, 

 although this question is not yet thoroughly understood. 



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. This year the most serious disease seems to be a brown 

 or rusty spot occurring in great numbers on the leaves. The disease 

 depletes the vigor of the whole plant and the leaves drop premature- 

 ly. No satisfactory treatment has yet been found. 



Not only is alfalfa worth more in New York as a forage plant than 

 as a seed producer, but the climatic conditions here do not seem to 

 be conducive to seed production. Moreover, if the plant is allowed 

 to produce seed it will not spring into growth until the following 

 year. Consequently our seed supply comes mostl}^ from the middle 

 and far West, and with it is often mixed the very minute dodder 

 seed. Dodder is a parasitic plant. Its seeds germinate in the soil, 

 but when the plant has attached itself to the alfalfa its stem con- 



