Group Title: CFREC-Apopka research report
Title: Changing medium pH with hydrated lime
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Permanent Link: http://ufdc.ufl.edu/UF00065298/00001
 Material Information
Title: Changing medium pH with hydrated lime
Alternate Title: CFREC-Apopka research report RH-92-1 ; Central Florida Research and Education Center-Apopka
Physical Description: 7 p. : ; 28 cm.
Language: English
Creator: Poole, R. T ( Richard Turk )
Conover, Charles Albert, 1934-
Central Florida Research and Education Center--Apopka
Publisher: University of Florida, Central Florida Research and Education Center-Apopka
Place of Publication: Apopka, Fla.
Publication Date: 1994
 Subjects
Subject: Liming of soils -- Testing -- Florida   ( lcsh )
Soil acidity -- Florida   ( lcsh )
Genre: government publication (state, provincial, terriorial, dependent)   ( marcgt )
bibliography   ( marcgt )
non-fiction   ( marcgt )
 Notes
Statement of Responsibility: R.T. Poole and C.A. Conover.
Bibliography: Includes bibliographical references (p. 3).
General Note: Caption title.
 Record Information
Bibliographic ID: UF00065298
Volume ID: VID00001
Source Institution: University of Florida
Holding Location: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: oclc - 70048974

Full Text


f\ u' ./ Changing medium pH with hydrated limeL 'I' r r

2.2 I R.T. Poole and C.A. Conover' SP 3 0 1994

University of Florida, IFAS University of Florida
Central Florida Research and Education Center Apopka
CFREC-Apopka Research Report RH-92-1 .


The pH of growing medium controls availability of nutrients used for plant growth.
Most foliage plants grow best in highly organic soilless mixes when pH is within a range of
5.3 to 6.5, although good quality plants have been obtained using mixes with lower and
higher pH levels (2, 3, 4). Medium pH is usually adjusted to the appropriate level by
additions of lime at the time components are mixed. Over time medium pH may drop due to
acidifying irrigation water and/or fertilizer, some of which can also acidify the medium. In
order to raise pH levels of medium in containers with established foliage plants, the most
widely recommended method has been addition of hydrated lime. Calcium hydroxide
(hydrated lime) is surface applied in a water suspension of no more than one pound/100 gal
or less to 100 ft2 of surface area (1). Plants should be retreated no more frequently than at 4
week intervals, if necessary, because it is thought that rapid pH change or the corrosive
action of the hydroxide ion may harm plants.

In recent years, several foliage plant growers in Central Florida have followed these
suggestions for pH adjustment and have not obtained desired results. Although these
recommendations are found in popular literature and we have used them ourselves, we could
find no evidence in scientific journals of experiments testing the ability of surface applied
liming agents to raise medium pH during plant production.

Materials and Methods

This 3 x 5 x 2 factorial experiment, with 5 replications per treatment, was initiated or
15 March 1991. Dieffenbachia maculata 'Camille' ('Camille' dieffenbachia) growing in 3
inch pots were transplanted into 6 inch containers filled with a medium composed of 3
Florida sedge peat: 1 builder's sand (3:1 by volume). The medium was amended with 1.5
lbs/yd3 Micromax (Grace/Sierra Co., Milpitas, CA 95035) and 0, 2.5 or 5 lbs/yd3 dolomite.
19-6-12 Osmocote (Grace/Sierra Co., Milpitas, CA 95035), a three month release rate
fertilizer, was surface applied, 5.7 g/6 inch pot, when transplanting was completed. Plants
were then placed in a greenhouse where maximum light intensity was 1500 ft-c and air
temperature ranged from 65 to 90F. Irrigation water with a pH measuring 7.2 was applied
3 times per week using overhead irrigation.






Jl11 IV nipJL 1771, VcdII U 1111.1 PL ICWIV1U V.UV, V.7, 1.0, .. I, Ul J.U 6\VIJ12
suspended in 100 ml of water, poured onto the medium surface. Four weeks later, on 8 May
991, these treatments were repeated for only half of the pots, so that an equal number of
ots tested received either one or two applications of Ca(OH)2.

Electrical conductivity (umhos/cm) and pH of the medium leachate were recorded on
* April, 18 April, 3 May, 16 May, 6 June, 3 July and 2 August 1991. Initial height was
measured on 19 March 1991 with final plant height measured on 2 August 1991. Plants
vere graded (based on a scale of 1 = dead, 2 = poor quality, unsalable, 3 = fair quality,
alable, 4 = good quality, salable and 5 = excellent quality plants) when experiment was
terminated on 13 August 1991.

Results and Discussion

'Camille' dieffenbachia plant height and grade were slightly affected by incorporated
dolomite levels (Table 1). Plants growing in medium containing no dolomite were only 0.8
inches shorter and received slightly lower grades than plants in medium with 5.0 lbs/yd3
dolomite. Increasing Ca(OH)2 from 0 to 1.8 g/6 inch pot increased plant height, but further
increases in Ca(OH)2, up to 3.6 g/6 inch pot, apparently caused some stunting. The number
if Ca(OH)2 applications (1 or 2) alone did not significantly affect plant quality or height.

Interaction between Ca(OH)2 rate and number of applications, however, produced
power grade 'Camille' dieffenbachia plants at the highest rate (3.6 g/6 inch pot) with two
applications (Table 2). Ca(OH)2 rate and number of applications also interacted to influence
H of medium leachate, which rose slowly over time when rate and number of applications
increased from 1 to 2 (Table 3).

The pH of leachate increased as dolomite incorporation rate increased and pH of all
dolomite treatments remained proportional over time (Table 4). Ca(OH)2 rate and number of
__^ 2-_ -' .-* !r i_ --.----- TT _-- !1 -1 T-.-I-- --_ -^ -- ^iL A ^ -^- -C ---I







In


ing Ca(OH)2 rate and number of applications raised the pH several months
of treatment, but plants grew less and received lower plant grades as rate and


number of applications increased. Also, the amount of time needed to raise pH was too long
considering the average crop turnover time for many foliage plant species. Therefore, these
preliminary data indicate that present recommendations are inadequate for rapid pH
adjustments. Calcium hydroxide is considered slightly soluble in water and calcium
carbonate, another popular liming agent, is practically insoluble in water (5). Other forms of
calcium such as calcium nitrate and calcium chloride which are both very soluble in water
(5), but not commonly used to adjust pH, should be tested for ability to raise medium pH
without harming foliage plants growing in the medium.

Literature Cited

1. Conover, C.A. and R.T. Poole. 1990. Light and fertilizer recommendations for
production of acclimatized potted foliage plants. Nursery Digest 24(10):34-36, 58-59.

2. Joiner, J.N., C.A. Conover and R.T. Poole. 1981. Nutrition and fertilization.
Chapter in: Foliage Plant Production, J.N. Joiner ed., Prentice-Hall Inc., Englewood
Cliffs, NJ.

3. Peterson, J.C. 1981. Modify your pH perspective. Florist's Rev. 169(4386):34-35,
92-93.

4. Wright, R.D. 1983. Study indicates need for changes in nutrition programs for
plants in containers. Amer. Nurseryman 157(1):109-111.

5. Windholz, M., S. Budavari, L.Y. Stroumtsos and M.N. Fertig. 1976. The Merck
Index. 9' edition, M. Windholz editor. Merck & Co., Inc., Rahway, NJ. pp. 210-
213.






Height and plant grade of Dieffenbachia maculata 'Camille' grown in a
medium treated with various lime applications.


Dolomite lbs/yd3


Plant gradez
13 Aug 1991
4.8


Height (in)
2 Aug 1991
15.6


16.1
16.4


Significancey
linear
quadratic


Ca(OH)2 g/6 inch pot
0.0
0.9
1.8
2.7
3.6
Significancey
linear
quadratic


No. of applications
1
2
SignificanceY
linear


16.2
16.3
16.3
15.9
15.6


5.0
4.7


16.1
15.9


TPlants were graded based on a scale of 1 = dead, 2 = poor quality, unsalable, 3 = fair
quality, salable, 4 = good quality, salable and 5 = excellent quality plant material.
Yns, *, **; Results nonsignificant, significant at P = 0.05 and P = 0.01, respectively.


Table 1.







Table 2.


Interaction effects of Ca(OH)2 application rates and number of Ca(OH)2
treatments on Dieffenbachia maculata 'Camille' plant grade, 13 August 1991.z


Ca(OH)2 g/6" pot/ Ca(OH)2 applied Ca(OH)2 applied
application 10 April 1991 10 April and 8 May 1991
0.0 5.0 5.0
0.9 4.9 5.0
1.8 5.0 4.9
2.7 5.0 4.9
3.6 4.9 4.6

zResults significant at P = 0.024.










Table 3. Interaction effects of Ca(OH)2 application rate and number of Ca(OH)2
treatments on pH of leachate collected from pots containing Dieffenbachia
maculata 'Camille', 2 August 1991.z
Ca(OH)2 g/6" pot/ Ca(OH)2 applied Ca(OH)2 applied
application 10 April 1991 10 April and 8 May 1991
0.0 4.4 4.1
0.9 4.6 4.7
1.8 4.9 5.0
2.7 4.8 5.5
3.6 5.1 5.6


zResults significant at P = 0.003.







Table 4.


Leachate pH from pots containing Dieffenbachia maculata 'Camille'. Plants
potted 15 March 1991. Ca(OH)2 applied 10 April to all plants. Ca(OH)2
applied 8 May to 1/2 the total number of plants.


Dolomite lbs/yd3 2 Apr 18 Apr 3 May 16 May 6 Jun 3 Jul 2 Aug

0.0 3.8 3.7 3.7 3.8 4.0 4.2 4.2
2.5 4.6 4.5 4.6 4.8 5.3 5.2 4.9
5.0 5.4 5.6 5.6 5.9 6.7 6.2 5.5


Significance

linear


** ** **


** *


quadratic


Ca(OH)2 g/6" pot

0.0


4.8
4.8
4.8
4.8
4.9


4.7
5.1
5.2
5.5
5.3


Significance

linear


* **


quadratic


ns ns


No. of applications


4.6


Significance

linear


** **


zns, *, **; Results nonsignificant,
respectively.


significant at P = 0.05 and significant at P = 0.01,


Yna; Not applicable. Ca(OH)2 treatment 1 applied 10 April 1991, treatment 2 applied 8
May 1991.







Table 5. Electrical conductivity (jmhos/cm) of leachate from pots containing
Dieffenbachia maculata 'Camille'. Plants potted 15 March 1991. Ca(OH)2
applied to all plants 10 April. Ca(OH)2 applied to 1/2 total number of plants
on 8 May 1991.
Dolomite, lbs/yd3 2 Apr 18 Apr 3 May 16 May 6 Jun 3 Jul 2 Aug
0.0 2493 2152 1425 1151 592 547 522
2.5 2756 2208 1325 980 351 401 376
5.0 2987 2533 1447 1007 336 392 398
Significancez
linear ** ** ns ** ** *
quadratic ns ns ns ns


Ca(OH)2g/6" pot
0.0 2723 2350 1518 1010 352 377 382
0.9 2794 2333 1383 991 385 427 435
1.8 2807 2280 1334 991 445 469 459
2.7 2778 2290 1380 1100 456 448 445
3.6 2616 2235 1384 1138 493 511 439
Significancez
linear ns ns ns ns ns
quadratic ns ns ns ns ns ns ns


No. of applications
1 2737 2260 1356 1058 410 417 424
2 2754 2335 1445 1034 442 476 440
Significance
linear nay na na ns ns ns

Zns, **; Results nonsignificant, significant at P = 0.05 and significant at 0.01,
respectively.
Yna; Not applicable. Ca(OH)2 treatment 1 applied 10 April 1991, treatment 2 applied 8
May 1991.




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