4 FARMERS ' BULLETIN 797. 



After it had been demonstrated that sweet clover would grow 

 successfully on soils too depleted for other crops, many experiments 

 were conducted to determine its value as forage. It was found 

 that it was not only a valuable soil-improving crop, but that it 

 made an excellent pasture and hay plant, quite palatable and rich 

 in protein. 



White sweet clover comprises a very large percentage of the acreage 

 seeded to sweet clover at the present time. On this account this spe- 

 cies ordinarily is referred to simply as " sweet clover." The yellow 

 biennial species is designated as yellow sweet clover, and the annual 

 yellow species as bitter clover, sour clover, or annual yellow sweet 

 clover. This usage has been adopted in this bulletin. 



The cultivation of sweet clover should be preceded by a thorough 

 understanding of the requirements for obtaining a stand. It can not 

 be grown successfully on all soils, as many assume from seeing it 

 growing in uncultivated places. Neither wdll it thrive in many sec- 



1 2 3 



FIG. 1. Seeds and seed pods of three species of Melilotus and seeds of alfalfa : 1, White 

 sweet clover ; 2, biennial yellow sweet clover ; 3, annual yellow sweet clover, or sour 

 clover ; 4, alfalfa. The small figures in each drawing show the natural size of the 

 seed. The venation and shape of the seed pods are important characters in distinguish- 

 ing the different species of sweet clover. 



tions of the country without careful preparation of the seed bed. 

 Sweet clover will not grow successfully in acid soils unless lime is 

 applied, but it will make a good growth in soils too low in humus to 

 grow red clover, provided the soil is neutral or alkaline. 



Sweet clover is an excellent plant to precede alfalfa, as the large 

 roots do much toward breaking up and aerating the subsoil. Con- 

 trary to the belief of many, it will not inoculate the soil for alfalfa 

 unless inoculation is applied to the sweet clover. If, however, the 

 soil contains but few inoculating germs, the sweet clover will serve 

 as a medium to inoculate it thoroughly. 



SPECIES OF SWEET CLOVER. 



A number of species of sweet clover are found throughout the 

 world, and most of them are native to temperate Europe and Asia 

 as far east as Tibet. 



