Group Title: ARC-A research report - Agricultural Research Center-Apopka ; RH-80-7
Title: Influence of soil acidity and liming on the production of leatherleaf fern
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 Material Information
Title: Influence of soil acidity and liming on the production of leatherleaf fern
Series Title: ARC-Apopka research report
Physical Description: 9 leaves : ill. ; 28 cm.
Language: English
Creator: Mathur, D. D
Agricultural Research Center (Apopka, Fla.)
Publisher: University of Florida, IFAS, Agricultural Research Center
Place of Publication: Apopka FL
Publication Date: 1980
Subject: Leatherleaf fern -- Growth -- Florida   ( lcsh )
Plants -- Effect of soil acidity on -- Florida   ( lcsh )
Genre: government publication (state, provincial, terriorial, dependent)   ( marcgt )
bibliography   ( marcgt )
non-fiction   ( marcgt )
Bibliography: Includes bibliographical references (leaves 8-9).
Statement of Responsibility: D.D. Mathur.
General Note: Caption title.
 Record Information
Bibliographic ID: UF00065980
Volume ID: VID00001
Source Institution: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: oclc - 71125555

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The publications in this collection do
not reflect current scientific knowledge
or recommendations. These texts
represent the historic publishing
record of the Institute for Food and
Agricultural Sciences and should be
used only to trace the historic work of
the Institute and its staff. Current IFAS
research may be found on the
Electronic Data Information Source

site maintained by the Florida
Cooperative Extension Service.

Copyright 2005, Board of Trustees, University
of Florida

S0-7 \IN HuE LI
D. D. Mathur
i-L tJ,3 Univer ity of Florida, IFAS
ARC-Apopka Research Report RH-1980-7
I.F..S.- niv. of Florid
n acid soil is one that contains more H ions than OH- ions in the

soil solution. In alkaline soils the reverse is true, OH" exceeds H In
a solution the concentration of H+ varies inversely as the concentration
of OH" in such a fashion that the product of the two concentrations is

always constant. When the concentration of one of these ions is determined,
the other is also know. Therefore, only H+ needs to be measured.
Soil acidity may be divided into two kinds "active" and "reserve"
acidity. Reserve acidity may also be referred to as potential or exchangeable
acidity. Taken together, the "active" and "reserve" acidity constitute
total soil acidity. The H+ concentration of the soil solution at any partic-
ular time is relatively small. In humid region soils, the removal from
colloidal fractions of positive ions, especially calcium,occurs constantly

through ion exchange. Their place is taken by hydrogen on the colloidal

complexes of the soil. Such reserves of H+ are designated as the reserve
acidity of the soil solution. The reaction of an acid soil can be influenced
only when enough lime is added to react with H+ (of soil complex) reserve
acidity as well as H+ (of soil solution) active acidity. The greater the
exchange capacity, the greater the reserve acidity and the greater the
difficulty of reducing the acidity of the soil solution. The magnitude of
this resistance to change is called buffer capacity.
Most plants grow best when soil pH is between 6.0 and 7.0, but general

experience has shown that leatherleaf fern requires a soil pH between 5.5
and 6.0. All plant nutrients are available between pH 5.5 and 7.0. In

general, pH and available calcium are closely related; but there are ex-

ceptions especially when sodium is present. Elements such as calcium and

magnesium are especially deficient in acid soils. In strongly acid soils,

aluminum, manganese and iron may exist in toxic quantities because of their

increased solubilities. In addition, these elements may react with phos-

phorus to form insoluble phosphates. In alkaline soils, pH 7.0 and above,

phosphorus, iron, manganese, boron, zinc and copper are usually unavailable

in quantities required by plants. Fertilizer programs for sandy soils

should be applied to maintain a steady pH.

Leatherleaf fern production is concentrated on the central Florida

ridge, which is dominated by 1) well drained to moderately well drained

soils, 2) soils dominantly thick to thin sands influenced by alkaline

materials and 3) soils dominantly thick to thin phosphatic sands and loamy

sands overlying fine textured materials. Under these situations extreme

care should be taken when establishing a new fernery. A soil test is

highly desirable because in some cases liming may not be necessary at the


Liming materials differ in their ability to neutralize acids. The

value of limestone depends on the quantity of acid that a unit weight of

the material will neutralize. This property, in turn, is related to

molecular composition of the liming material, chemical purity, solubility

in water and its freedom from inert contaminants such as clay. Pure

calcium carbonate is the standard against which other liming materials are

measured. The neutralizing value of calcium carbonate is 100 percent.

A list of neutralizing values of common liming materials is shown in

Table 1.

Table 1. Neutralizing value of common liming materials.
Material Neutralizing value (%)
CaCO3 Calcitic limestone 100
CaO Burnt lime 178
Ca(OH)2 Hydrated lime 136
CaMg (C03)2 Dolomitic lime 109
CaO MgO Dolomitic oxide 195
Basic slag 85
Calcium silicate slag 85

Ca = Calcium, Mg = Magnesium, CO3 = carbonate, 0 =
oxide, OH = hydrate.

Mode of action: Mineral clays in soils are of two general classes 2:1
and 1:1. The 2:1 relates to 2 layers of silica and one of alumina (Al) and

1:1 relates'to one layer of silica and one layer of alumina. Liming reaction

in 'each is complex. A soil reaction may be generalized as follows:
Al (Soil) + 3 Ca CO3 + 6H20 > 3 Ca (Soil) + 2 Al (OH)3 + 3 CO2
When lime is added to a soil,Ca ions replace Al ions on the exchange site

through mass action. The displaced Al ions hydrolyze to form gibbsite which

is inert and water and CO2 are formed. Due to the removal of active Al

from the soil complex through precipitation and gibbsite, the increase in
OH ions in the system and the increase in the base saturation of the soil
complex, the soil pH increases. How much lime should be added? The amount

of lime to be added is directly'related to the exchange capacity of soil

or the Feserve acidity.

Experimentation on the effect of dolomite and micronutrients incor-
porated into the soil before planting on the yield of leatherleaf fern has

shown that addition of both dolomite and micronutrients reduced yield. The

addition of dolomite at the rate of 1000 pounds per acre has been a frequent

practice among fern producers.

The raised pH due to the application of dolomite would then adversely

affect the growth and yield of leatherleaf fern. Field observations and
planting history of the leatherleaf fern in DeLand, DeLeon Springs and Lake

County have revealed that application of dolomite when establishing a fernery

has sometimes caused frond burn and reduction in the yield of leatherleaf fern.

The rate of application of two types of lime to two types of soil for 1000

square feet and per acre is reported in Table 2. If on a light, sandy soil you

have a pH of 4 and wish to raise it to pH 6, add 1050 Ibs hydrated lime or 2100

Ibs of ground limestone per acre, if your pH is 5.25, add 300 Ibs hydrated lime

or 600 Ibs ground limestone. On the other hand, if you have a pH of 4.5 and

wish to raise it to 5.5, add 600 Ibs hydrated lime or 1200 lbs ground limestone;
the difference between the two. Most of Florida's lime materials are soft rock

materials which are highly soluble and fast reacting which may be disadvantageous.

Because of the nature of our soils, the long term benefit of our soft materials

may be inferior to lime materials from other states which are harder and less


Readily water soluble hydrated lime and burned lime are the two liming

materials used in the ornamental industry. Both have relatively high

neutralizing values and should be used in smaller quantities than other liming
materials (Table 1). They are caustic and will cause skin irritation. Direct

application to plants may cause foliage burn, Basic slag is a by-product of

the steel industry. It has low neutralizing value as compared to other liming

materials but it also contains phosphorus and other impurities which increase
its value as a soil amendment.

Can gypsum (CaSO4) be used as a liming material? Gypsum, a neutral

salt, is not a true liming material and does not neutralize soil acidity. A

true liming material contains calcium and neutralizes soil acidity, A mixture

of dolomite and gypsum has the capacity to supply calcium, magnesium

Table 2. Approximate rates of application of
for pH adjustment of typical Florida soils

hydrated lime and ground limestone
used to produce leatherleaf fern.1

Light sandy soil (St. Lucie) Medium sandy soil (Lakeland)
Soil Hydrated lime Ground limestone Hydrated lime Ground limestone
Acidity Ibs/ Ibs/ Ibs/ lbs/
(pH) 1000 ft Acre 1000 ft2 Acre 1000 ft2 Acre 1000 ft Acre
4.00 24.1 1050 48.2 2100 32.1 1400 64.3 2800
4.25 20.7 900 41.3 1800 27.5 1200 55.1 2400
4.50 17.2 750 34.4 1500 23.0 1000 45.9 2000
4.75 13.8 600 27.5 1200 18.4 800 36.7 1600
5.00 10.3 450 20.7 900 13.8 600 27.5 1200
5.25 6.9 300 13.8 600 9.2 400 18.4 800
5.50 3.4 150 6.9 300 4.6 200 9.2 400
6.00 None None None None None None None None

Light sandy soil To raise pH 4 to pH 6, add
ground limestone/acre, if pH is 5.25, add 300

limestone. To raise pH from
hydrated lime or (1500 300

1050 Ibs hydrated
Ibs hydrated lime

4.5 to 5.5 use the difference (750
= 1200) Ibs ground limestone/acre.

lime or 2100 Ibs
or 600 Ibs ground
- 150 = 600) Ibs
To find the

amount of lime for 1000 sq ft and medium sandy soil follow the same procedure as
light sandy soil.
2Although use of Table 1 on page 3 would indicate that higher levels of hydrated
lime may be required to change pH, rates in Table 2 are proposed with safety of
the crop in mind since most growers apply hydrated lime through the irrigation
system. One month after application of hydrated lime, check pH again and reapply
if necessary.

and sulfur while at the same time producing a small increase in pH. Addition

of sufficient liming material to supply adequate calcium and magnesium may in-

crease soil pH in such a way as to reduce the availability of essential macro

and micronutrients.

Reduction time of lime: The approximate reaction time for dolomite according

to the typical mesh sizes found in various grades is given in Fig. 1. By

Florida law 50% of the material must pass a 50 mesh sieve, 80% must pass a

20 mesh sieve and not more than 10% retained on a 10 mesh sieve.

The data in Fig. 1 show that 6 to 9 months reaction time is required

to get maximum benefit from the added lime. One could not expect to obtain

maximum benefit from lime applied immediately before planting, but, some

benefit may be obtained from the added Ca and/or Mg thus it is never too late

to add lime. The above data was obtained by using dolomite but in Florida

high solubility liming materials are available which react faster than dolomite.

To decrease soil pH wettable sulfur usually is added. One milliequivalent

of sulfur (0.016 gram) by oxidation will form 1 milliequivalent of sulfuric

acid. On that basis 1 pound of elemental sulfur will produce an amount of

acid whose neutralization will require 3 pounds of calcium carbonate. Gen-

erally it takes approximately 1/3 the amount of wettable or super-fine sulfur

to decrease pH 1 unit as it does ground limestone or dolomite to raise pH.

In other words, divide the amounts listed for a particular soil type in Table

2 by 3 to determine the amount of wettable or super-fine dusting sulfur needed

to acidify the soil 1 pH unit. Not more than 5 pounds per 1000 ft2 should be

used in 1 application because in soil sulfur oxidizes and mixes-with water
to form a strong acid that can burn the roots of plants. Reapply in 8 weeks
or more if pH is not at desired level.


7..0 50%


6.0 s o

5.5 9.0 10 %


4.6 ....
0 6 12 18

Effect of mesh size on reaction time or lime.

Figure 1.


Additional References

1. Baker, A. S. 1970. The degree of mixing of lime affects the

neutralization of exchangable aluminum. Soil Sci. Soc. Amer. Proc.


2. Coleman, N. T., E. J. Kamprath, and S. B. Weed. 1958. Liming.

Advan. Agron., 10:475.

3. Coleman, N. T., and G. W. Thomas. 1967.- The basic chemistry of

soil acidity. In: R. W. Pearson and F. Adams (eds.) Soil Acidity

and Liming. Agronomy 12:1-41. Amer. Soc. of Agron. Madison, Wis.

4. Duncan, J. M. 1951. The lime industry in Florida. An intangible

analysis. Eng. Progress of the Univ. of Florida. Vol. V., No. 12.

Supplement, Fla. Eng. and Ind. Exp. Sta.

5. Hopkins, R. H. 1942. The dolomite limestones of Florida. Florida

State Board of Conservation. Florida Geological Survey. Report of

Investigation No. 3.

6. Jackson, M. L. 1960. Structural role of hydronium in layer silicates

during soil genesis. Int. Congr. Soil Sci., Trans 7th (Madison, Wis.,

USA). Vol. II, 445-455.

7. Keeney, D. R., and R. B. Corey. 1963. Factors affecting the lime

requirements of Wisconsin soils. Soil Sci. Soc. Amer. Proc. 27:277-280.

8. McLean, E. 0. 1970. Lime requirements of soils inactive toxic sub-

stances or favorable pH range. Soil Sci. Soc. Amer. Proc. 34:363-364.

9. Perkins, H. F. 1963. Lime-comparison between different sources of

lime. New Developments in Fertilizer and Lime, November 6'and 7,

Rock Eagle, Georgia.

10. Poole, R. T. and C. A. Conover. 1973. Influence of dolomite and

micronutrients on yield of leatherleaf fern. Proc. Fla. State Hort.

Soc. P6:372-374.


11. Shaw, W. M., and B. Robinson. 1959. Chemical evaluation of neutralizing

efficiency of agricultural limestone. Soil Sci. 87:262.

12. Shaw, W. M. 1961. Rate and reaction of limestone with soils. Soils

Fertilizers, 24:297.

13. Schollenburger, C. J., and C. W. Whittaker. 1962. A comparison of

methods for evaluating activities of agricultural limestones. Soil

Sci. 93:161.

14. Whittaker, C. W., M. S. Anderson and R. F. Reitemier. 1951. Liming

soils for better farming. USDA Farmers Bull. No. 2032.

15. Whittaker, C. W., C. J. Erickson, K. S. Love and D. M. Carroll. 1959.

Liming qualities of three cement kiln flue dusts and a limestone in a

greenhouse comparison. Agron. J. 51:280.

16. Woodruff, C. M. 1948. Testing soils for lime requirement by means of

a buffer solution and the glass electrode. Soil Sci. 66:53-63.

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