266 THE FORAGE AND FIBER CROPS IN AMERICA 



329. INFLUENCE ON OTHER CROPS. The Alabama Station conducted more 

 than fifty experiments during five years to determine the effect of cowpeas 

 and velvet beans on the yield of other crops. The average increase in the 

 yields of succeeding crops was practically the same, whether cowpeas or velvet 

 beans were used. In the case of velvet beans the whole plant was used, while 

 in the case of cowpeas the pods were first harvested. The table on page 265 

 shows the increase in yield of succeeding crops caused by plowing in the 

 whole crop and by plowing in roots and stubble only. 



The greater increase was obtained from wheat and oats which were fall 

 sown. This was attributed to the fact that these crops left the land unoc- 

 cupied for the shortest length of time. Plowing in the vines gave larger 

 yields with spring sown crops than where only the roots and stubble were 

 plowed under, and the effect on sandy land was less transitory, increased 

 yields being obtained in the third and fourth crops. The fact that wheat 

 and oats increased less in yield in the first crop where vines were plowed 

 under than where roots and stubble only were plowed under was attributed 

 to the former leaving the land too loose, a condition that could, it was be- 

 lieved, have been avoided by better preparation. 



Since cowpeas are known to acquire nitrogen from the air in large quanti- 

 ties and because of their luxuriant growth above ground, it is considered 

 good farm practise to plow this crop under in order to enrich the soil, and 

 to increase the supply of organic matter. The Tennessee Station, however, 

 conducted an experiment to determine the relative value of cutting off, plow- 

 ing under, and pasturing off this crop, with the following results: 



In discussing the results, the Station l concluded that, considering the high 

 feeding value of cowpeas when fed to milch cows, cowpeas should always be 

 fed and the droppings returned to the land. On the other hand, although the 

 highest yield obtained was where cowpeas were cut off and a home mixed 

 complete fertilizer used, in reality when the cost of the fertilizer was con- 

 sidered it was not more profitable than where the cowpeas alone were plowed 

 under. Where cowpeas were plowed under and commercial fertilizers added, 

 the returns were larger for the same relative cost than where commercial 

 fertilizer alone was used; and when so used, experience indicated that lime, 

 phosphates, and potash together gave the best results. 



1 Tennessee Sta. Bui. Vol. XIV (1901), No 2, pp. 48-59. 



