312 
Journal of Agricultural Research 
Vol. XIV, No. 8 
2 POTASS/UM SULPHATE 
2 POTASS/OM SULPHATE +Ca C 0 3 
2 B/OT/TE 
2 B/OT/TE-/ Ca C 0 3 
■ 91 * 
2 MOSCOWTE 
2 MOSCOW TE / Ca CO s 
Exceedingly small amounts of potash have been removed from the soil 
with the microline treatment. It gradually increases through treatments 
of orthoclase, muscovite, biotite until the maximum is reached with the 
soluble material (PL 49, D). 
ACTIVE SOIIy POTASH AFTER TWO YEARS 7 CROPPING 
In order that the active or readily soluble soil potash left after two 
years 7 cropping might be determined, samples of each pot were subjected 
t . to solution in A r /5 
nitric acid. The sam¬ 
ples were obtained by 
making three borings 
in each pot through 
the entire column of 
soil. The portions re¬ 
moved by each bor¬ 
ing were well mixed, 
oven-dried, and bot¬ 
tled for analysis. 
Thirty-gm. portions 
were agitated with 
500 cc. of N/5 nitric 
acid for 96 hours, 
after which the pot¬ 
ash was determined 
colometrically. Table 
X gives the average 
amounts of potash 
removed by N/5 nitric 
acid. 
Considerably more 
potash was extracted 
by dilute acid when 
potassium sulphate 
had been added than 
when none had been 
used. Biotite and muscovite produced about the same quantity, more 
than double the amount of the controls. Very little, if any, increases 
could be discerned from the pots to which orthoclase or microcline had 
been applied. 
Carbonate of lime does not have the slightest effect on any minerals 
used toward increasing the amount of potash soluble in iV/5 nitric acid. 
In a majority of cases when the carbonate of lime has been used there 
are slight losses of potash from solution. 
20 PT// 0 CLASE 
20277 / 0 CLA$E+CaC 0 3 
2 M/CB 0 CL/ME 
2 M/CPOCL/A/E+Ca C 0 3 
COA/TPOL. 
COA/TPOL/Ca C 0 3 
Fig. 4. —Rate of growth of cowpeas under similar conditions fertilized 
with double applications of potash minerals and calcium carbonate. 
