INFLUENCE OF GROWTH OF COWPEAS UPON SOME 
PHYSICAL, CHEMICAL, AND BIOLOGICAL PROPERTIES 
OF SOIL 
By C. A. LeCtair, 1 
Assistant Professor of Soils, University of Missouri 
INTRODUCTION 
In the past 25 years much experimental work has been done with 
cowpeas (Vigna sinensis) in relation to cultural methods, fertilization, 
and variety tests, but practically nothing has been written with regard 
to the direct effect of the plant upon the soil. Some have expressed the 
belief that cowpeas are capable of producing a loosening effect upon the 
soil, but no authentic experimental data are available. 
HISTORICAL SUMMARY 
An exhaustive study of research literature revealed that previous 
work along the particular line referred to has been exceedingly limited. 
The data at hand bear only indirectly upon the work of this experiment, 
but are worthy of consideration. 
With regard to the effect of shading on soil, Biihler 2 reports having 
carried on an experiment on four broad plots of ground. One was 
exposed to sun and wind; the others were shaded by horizontal wooden 
trellises placed around each plot 40 cm. above the ground and so arranged 
as to cut off one-fourth, one-half, and three-fourths of the sunlight from 
respective screened plots. 
Data at the end of the experiment showed that at midday the shaded 
plots had a lower temperature than the open plot by from 2 to 10 
degrees centigrade. However, the cooling by night under the shaded 
plot was very slight, being less than 2 degrees centigrade, which explains 
the effectiveness of a windbreak in preventing injury by frost. In rainy 
weather the variation of temperature either by day or by night was 
much smaller. 
The relative evaporation from plots throughout the test was as follows: 
Treatment. 
No shade. 
One-fourth shade. . 
One-half shade. 
Three-fourths shade 
Percentage of 
evaporation. 
. . IOO 
•• 84 
• ■ 71 
62 
1 The writer desires to acknowledge his gratitude to Prof. M. F. Miller, of the Missouri Experiment Sta¬ 
tion, under whose direction these experiments were carried out. 
2 Biihler, A. Influence des treillis abris sur la temperature du sol et sur 1 ’evaporation. In Ciel et Terre, 
ann. 17, no. 1, p. 21-22. 1896. 
Journal of Agricultural Research, 
Dept, of Agriculture, Washington, D. C. 
bb 
(439) 
Vol. V, No. 10 
Dec. 6, 1915 
Mo.—1 
