72 
FLORIDA STATE HORTICULTURAL SOCIETY. 
up which the roots actually get hold of, 
and that which is mechanically held, and 
in such coarse sand, the amount mechani¬ 
cally held is quite small as has been dem¬ 
onstrated by leaching tests. 
Even organic fertilizers such as bone 
meal, cottonseed meal, dried blood and 
castor pomace are slowly converted into 
soluble forms in the soil, and on account 
of the almost entire absence of those 
substances which produce absorption phe¬ 
nomena (a binding of soluble plant food) 
a large part of this soluble plant food, if 
not used at once by the plants, goes down 
with the first rain that comes. 
VALUE OF SLOWLY AVAILABLE MATERIALS. 
However, there is a great advantage in 
using these slowly available forms over 
the readily soluble forms, for all the while 
that they are thus being made available, 
the plants are being benefited, and the ex¬ 
cess to be carried away by percolation is 
not so great. 
I believe one of the qierits of slag phos¬ 
phate lies in its somewhat insoluble, but 
nevertheless slowlv available form of 
phosphoric acid. When applied from 
year to year, a small amount is being ren¬ 
dered available all the time, and at the 
‘same time no very great amount is lost 
hy j>ercolation. I further believe that if 
we could get a more slowly available fomi 
of potash for such soils, the problem of 
fertilizing pineapples would be simplified 
and the expense reduced. The good re¬ 
sults obtained with tobacco stems might 
possibly be attributed to the fact that the 
]>otash becomes slowly available, and thus 
in the end is nearly all taken up by the 
plant. 
PLANT FOOD AND CAPILLARY ACTION. 
But some one asks, may not much of 
this lost plant food be recovered and 
brought within reach of the plant roots 
by the capillary action of the soil mois¬ 
ture? 
If the soil were a clay or a clay loam 
the answer would certainly be in the af¬ 
firmative, but in such coarse sandy soils 
the conditions are very different. It is a 
well know physical fact that when three 
tubes of different internal diameters are 
placed open end in water, the water will 
rise highest in the smallest tube, that is 
the smaller the tube the greater the capil¬ 
lary action. So with the soil, the finer the 
particles the greater the capillary action, 
and as the particles of sand composing 
the pineapple soils are very large in com¬ 
parison with the particles that make up 
clay soil, so the amount of water, and 
hence of plant food, brought up from a 
deep soil by capillary action is correspMDnd- 
ingly smaller. Hence it is that plant food 
when once lost in the waters of the sub¬ 
soil, are recovered but slowly and with 
great difficulty by capillary action. This 
was well illustrated by another experi¬ 
ment conducted in our laboratory. 
Over the end of a glass tube of about 
3-4 in. internal diameter, was tied a piece 
of muslin cloth, and into the tube was 
placed the pineapple soil to a depth of 12 
in. The tube was then suspended so that 
the end over which the cloth was tied just 
touched the surface of distilled water con¬ 
tained in a beaker. At the end of three 
days the highest point at which the soil 
had been moistened by capillary water 
was 3 3-8 in. The same experiment was 
tried with the Columbia Co. soil, and the 
S. C. clay soil with the result that at the 
