Dec. 6, 1915 
Influence of Growth of Cowpeas on Soil Properties 
447 
under adjacent, similarly treated, fallowed plots. (See “ Historical 
summary.”) 
Although there is a wide range in the total bacterial count under the 
respective treatments, the only certain conclusion which can be drawn 
is that under cowpeas we have larger numbers of bacteria than where 
no crop is on the land. The ammonifying and nitrifying efficiency of 
these soils as affected by the summer's treatment seemed to have been 
only influenced by the varied conditions noted, but no correlations can 
be drawn. Thus, briefly summing up, it might be said that the main¬ 
tenance of soil structure from spring to fall by the growth of cowpeas on 
the land is due partially to the shading effect of the foliage, which, like 
the artificial shade, resists the compacting effect of beating rains and 
baking sun. Besides this, there seems to be a marked correlation between 
the friability of the soil under cowpeas and the bacterial flora present. 
Where present in largest numbers, they possibly bring about a greater 
production of active humus and so maintain the looseness of the soil. 
SUMMARY 
(1) The data given show conclusively that cowpeas tend to maintain 
the friability of loose and compact seed beds. 
(2) It was also noted that, while cowpeas take more water from the 
soil than evaporates from uncultivated adjacent lands, the removal of 
water is from below the second foot of soil. 
(3) Land that was plowed and left uncultivated or plowed and seeded 
to cowpeas contained a greater quantity of nitrates in the soil at the 
end of the season than unplowed land similarly treated. 
(4) The bacterial activities of the soil upon which cowpeas were grown 
tended to show that the soil organisms are probably a factor in prevent¬ 
ing the packing of soil, as also is the mechanical shade effect of the crop 
grown upon the land. 
