28 
slight average increase and a profit of $2.16. In addition to complete 
fertilizer, lime shows an increase of 251 pounds of seed cotton, and its 
application here was at a profit of $6.17, and for the complete applica¬ 
tion—LbTPK, the profit was $17.62. 
The main increase yields and profits came from nitrogen and potash. 
On the whole, practically no beneficial effect was seen from the applica¬ 
tion of phosphoric acid. The application of lime was in general, accom¬ 
panied with some profit. 
Table 12 gives the average mineralogical and chemical composition 
of three samples of soil taken from the Edgecombe Farm. 
The chemical analyses show that the soil from this farm is low 
in nitrogen and phosphoric acid, and compared to most of the Pied¬ 
mont and Mountain soils, low in potash and lime. The mineralogical 
analyses show that the supply of potash is held mainly in the felspars; 
there being only a trace of muscovite in the sands and little more in 
the silt separates. What biotite found in the silt has been altered 
for the most part. Much of the orthoclase found here has been 
weathered, but microcline presents pure clean faces and sharp edges 
showing that little decomposition has taken place. Though the chem¬ 
ical analyses show that there is about 3,000 pounds of potash compounds 
per acre in this soil, the field results for seven years indicate that this 
element can be applied with profit. This fact bears out somewhat 
the conclusions drawn by other investigators as to the availability of 
potash when held in the form of felspar. In this soil the greater part 
of the orthoclase shows such marked signs of chemical decomposition, 
that it is reasonable to assume that mi*crocline furnishes the greater 
part of the potash here. 
The Mountain and Piedmont soils, experimented, wdth, have the 
micas as their principal source of potash. In these soils the amount 
of organic matter is little higher than that from the Edgecombe Farm. 
It would not seem probable that the difference in the potash require¬ 
ments are due to the amount of decaying organic matter liberating 
more potash in the Piedmont and Mountain soils and not so in this 
soil from the Coastal Plain. The difference must be due to the way 
the potash is held in these soils. 
Lime is supplied to the soil from the Edgecombe Farm almost entirely 
as epidote, there being only a trace of hornblende, and no plagioclase 
felspar present. The field results obtained on this farm indicate that 
lime can be used here at a profit, whereas the chemical analyses show 
that the surface soil.to a depth of 6% inches contains some 3,000 
pounds of this material. 
In this soil the supply of phosphoric acid is very low, that which is 
present is in other forms than the mineral apatite. Most careful 
examinations have failed to show this mineral in a single instance. 
