| Material Information
||Leaching of potting media
||ARC-A research report
||3, 1 leaves : ; 28 cm.
||Poole, R. T ( Richard Turk )
Agricultural Research Center (Apopka, Fla.)
||IFAS, University of Florida, Agricultural Research Center-Apopka
||Place of Publication:
||Potting soils ( lcsh )
Soils -- Leaching -- Florida ( lcsh )
||government publication (state, provincial, terriorial, dependent) ( marcgt )
non-fiction ( marcgt )
||Statement of Responsibility:
||Richard T. Poole.
| Record Information
||University of Florida
||All rights reserved by the source institution and holding location.
||oclc - 70920046
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Copyright 2005, Board of Trustees, University
LEACHING OF POTTING MEDIA Ir LD'.%Lr.
Richard T. Poole FB i7 83
IFAS, University of Florida
Agricultural Research Center L.A..- Univ. o
ARC-A Research Report RH-81-17 "FS-Un .of Fi
To leach, according to Webster, is to dissolve out by the action of
a percolating liquid, or to subject to the action of percolating liquid
(for example, water) in order to separate soluble components.
Indoor foliage plants need water and nutrients to grow, BUT, does
the potting medium need to be leached for the plant to grow satisfactorily?
Does water need to be applied in sufficient quantities so that water and
nutrients pass from the potting medium with each irrigation? Many people
think, yes! The importance of leaching is taught in the classrooms and
S acknowledged by commercial producers of plants. Textbooks state, "very thor-
ough watering is necessary; there is comparatively little danger of too
liberal applications of water; enough water should be applied to result in
some drip through." But excessive amounts of water restrict soil
aeration and necessitate use of extra fertilizer.
Until recently water and fertilizer have been relatively inexpensive
items for the production of foliage plants, but cost of fertilizer has
increased greatly and water usage is now a critical problem. Water
shortages have appeared throughout the country, and certain areas of
Florida are facing crucial water shortages. There is also growing concern
regarding contamination of water supplies by run off from excess application
of fertilizers. Ideally, application of water and fertilizer would result
in no loss of water or fertilizer from plant containers while producing
excellent quality foliage plants. Thus, water use efficiency and application
should now be among the highest priorities in selecting irrigation systems.
Many experiments have been conducted to determine effects of
irrigation frequencies on plant growth, but the actual amount of water
needed to produce a marketable plant has been studied only recently.
Several studies have been conducted at the Agricultural Research Center-
Apopka, supported in part by a grant from the Foliage Education and
Research Foundation, Inc., to determine the interrelationship between
quantity of water and fertilizer applied, and the effect of this inter-
relationship with water usage and plant growth.
The first experiment showed the importance of applying the correct
amount of nutrition (Table 1). As fertilizer levels increased, efficiency
of water usage and top dry weight decreased. Examination of soluble salts
levels mhoss x 10-5) revealed the damaging effect of fertilizer applied.
As the soluble salts increased because of the increase in fertilizer
rate, root damage occurred and less water was utilized and top growth was
A second experiment (Table 2) showed an interesting relationship
between rate of fertilizer and volume of water applied. The high level
of fertilizer produced poor growth, while the low fertilizer level
produced good growth with top weight increasing as volume of water in-
creased, but root grade decreased as volume of water increased. Again,
soluble salts reflected the rate of fertilizer and water applied.
Other experiments have been conducted comparing plants grown in
pots with no leaching to plants grown in pots with conventional leaching
(Table 3). Plants supplied with the recommended fertilizer rate and
grown in potting media with good aeration and cation exchange properties
will produce good quality foliage plants comparable to plants grown in
potting media that are leached.
Work at the Agricultural Research Center Apopka has shown that good
quality foliage plants can be grown with no leaching of water or fertilizer,
resulting in no waste of water or fertilizer and saving the foliage
producer time and money as well as eliminating addition of nutrients to
the ground water supply. However, recommended amounts of fertilizer should
be applied to a soil with good aeration and water holding capacity and
high cation exchange capacity.
Table 1. Water utilization and plant growth resulting from 3 levels
of N-P-K applied with each irrigation.
Water utilized Top dry mhos x 10-5
Concentration (%) wt (g)
250-110-200 88 24 185
500-220-400 63 19 475
750-330-600 50 15 515
250-110-200 70 12 158
500-220-400 61 11 510
750-330-600 45 9 680
250-110-200. 52 8 225
500-220-400 49 7 550
750-330-600 52 6 730
Table 2. Interrelationship of volume of water applied and fertilizer rate
on water usage and plant growth of Peperomia obtusifolia and soluble
salts of final leachate.
Cone (ppm) Vol (ml) Top fresh Root
200-90-170 water weight grade mhos
N-P-K applied (g) (5 = best) x 10-5
200-90-170 4140 139 3.7 170
800-360-680 4140 118 1.0 700
200-90-170 5040 156 3.3 165
800-360-680 5040 118 1.0 654
200-90-170 5940 165 2.8 172
200-360-680 5940 116 1.0 621