4 BULLETIN 1378, U. S. DEPARTMENT OF AGRICULTURE 
for planting the crop, of the seed and seeding, and the plowing under 
of the vegetative matter produced by each crop on an acre basis is 
given in Table 4. 
Table 4. — Cost of growing cover crops in a pecan orchard on Norfolk fine sandy 
loam from 1918 to 1923 on an acre basis l 
Fall 
crop 
Summer crop 
Year 
Plowing 
under 
summer 
crop and 
preparing 
seed bed 
Seed and 
planting 
Plowing 
under 
winter 
crop and 
preparing 
seed bed 
Seed and 
planting 
Total 
1918 
$2.00 
2.50 
2.00 
1.50 
1.75 
1.75 
$1.00 
1.25 
1.00 
.75 
1.00 
1.00 
»$2.00 
2.50 
2.00 
1.50 
1.75 
1.75 
$5.00 
1919 
$2.00 
1.75 
1.50 
1.25 
1.50 
8.25 
1920 
6.75 
1921 
5.25 
1922 
5.75 
1923 
6.00 
> The items cover the expense of labor and team, no allowance for overhead or machinery depreciation 
being included. 
* Cost of summer cultivation. 
The cover crops improved the soil from year to year and were a 
success each year. Large quantities of vegetable matter were plowed 
into the soil each spring and fall. The cover crop of velvet beans 
grown in the summer of 1923 is shown in Plate I. Here the luxuri- 
ant growth was turned under in the fall for green manuring. 
IMPROVEMENT OF THE SOIL 
The soil's organic matter and nitrogen content, which seem to be 
the most important soil-fertility factors concerned, were noted 
from time to time. Composite samples of soil were taken from the 
orchard in 1918, 1921, 1922, and at the end of 1923 and the acidity, 
nitrogen, and organic matter determined. The results are given 
in Table 5. 
Table 5.- 
- Analyses of soil from a pecan orchard on Norfolk fine sandy loam at 
Cairo, Ga., 1 in stated years 
Constituents 
(per cent) 
Acidity 
(pU) 
Year 
Organic 
matter 
(C)» 
Nitrogen 
(N) 
1918 
0.64 
.90 
1.23 
1.39 
0.031 
.040 
.050 
.061 
5.4 
1921 
6.0 
1922___ 
6.0 
1923_._ 
5.8 
i Analyses by P. D. Boone and acidity determinations by E. F. Snyder, Office of Soil-Fertility Investi- 
gations, Bureau of Plant Industry. 
*To convert this carbon figure to organic matter, multiply by 1.73. 
The acidity of the soil is expressed in terms of the intensity of the 
acid character of the soil, technically called its P ? value. 
A neutral soil has a P H value of 7 and an acid soil a P H value 
below 7, being increasingly more acid as the value becomes smaller. 
