40 BULLETIN 981, U. S. DEPARTMENT OF AGRICULTURE. 
ing, the seed of soy beans is somewhat larger than that of cowpeas, 
but there is a wide variation among varieties in this respect. The 
Peking and the Arlington are two varieties which have exceptionally 
small seed. These varieties average 6,800 seeds per pound, while 
four other well-known varieties, Wilson, Guelph, Ito San, and Mam- 
moth, average only 2,600 seeds to the pound. This difference in the 
size of the seed should be taken into consideration in determining the 
proportions of grass and legume seed. The varieties mentioned 
above are all very well adapted for use in mixtures, because all of 
them make a luxuriant growth of vines. 
The greatest drawback to the use of mixtures lies in the difficulty 
of seeding the two elements uniformly. This can be accomplished 
most easily by broadcasting the mixture. If a drill is used, great 
caution is required to keep the Sudan grass and legume seed thoroughly 
mixed in the drill box. Experimental plantings have been made 
most successfully by going over the ground twice with a drill in which 
alternate holes have been closed. In this way rows of the legume 
can be made to alternate with rows of Sudan grass. This method 
is too expensive, however, for extensive use by farmers. With drills 
which have a grass-seeder attachment it is possible to run the Sudan 
grass seed through the seeder and the cowpeas or soy beans through 
the grain feed. 
General experience indicates that it is usually more practicable, 
except in localities where cowpeas or soy beans succeed especially 
well, to sow the Sudan grass an'd legumes on separate fields. The 
greater ease of seeding and harvesting the crops is likely to overcome 
the advantages which might be derivéd from a mixed seeding. 
Another feature of mixed plantings of annual crops which has re- 
ceived little attention is the effect on the chemical composition of the 
Sudan grass produced by its association with the legumes. Lyon and 
Bizzell (13, pp. 365-368), of New York, found a marked increase in 
the percentage of protein in nonlegumes when grown in association 
with legumes; e. g., timothy with alfalfa and oats with field peas. 
Westgate and Oakley (27), on the contrary, could detect no effect of 
this nature. 
TasBLE VIII.—Proportions of protein and ash in Sudan grass when grown alone and 
when grown with legumes at the Arlington Experimental Farm in 1913. 
i 
Crop. _ | Protein. | Ash. 
Suda Srass alone a. sans see hs ee eae se ae ees eee per cent.. 6. 63 7. 46 
iD) OFREI EER ae few se ee one on Se Sie hn © SER Ne eee eee does} 6. 59 | 7. 56 
SudanterassiwithycowPeas-nne == ae ae Sens eee ee oe ee re ee eee dona! 6. 40 | 8. 60 
Sudanierassiwithisoy peanses 22) aoe Nee 8 ee eee Gones. 7.30 | 10. 46 
Sudanerasswva LoibOna VAS bi WCADS=. eee ae Re ne ee dows 7. 66 | 9. 11 
IAWVeraA Ce ISUGAMISTASS ALONE 8.2 ee Ma ove Se ce oe a2 ap ea ee dos 6.61 | 7.51 
ACVeETACe OU AMeTASS WALI ES IMIES = mes ope cas eee re aera eee oe Gore 412 9. 39 
