Group Title: Research report (North Florida Research and Education Center (Quincy, Fla.))
Title: Source of p, lime application sequence, and residual effects on p availabilty to watermelon
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 Material Information
Title: Source of p, lime application sequence, and residual effects on p availabilty to watermelon
Series Title: Research report (North Florida Research and Education Center (Quincy, Fla.))
Physical Description: 15 lpages : ; 28 cm.
Language: English
Creator: Rhoads, Fred ( Frederick Milton )
Olson, Stephen Michael
North Florida Research and Education Center (Quincy, Fla.)
Publisher: North Florida Research and Education Center
Place of Publication: Quincy Fla
Publication Date: 1994
 Subjects
Subject: Watermelons -- Research   ( lcsh )
Genre: bibliography   ( marcgt )
non-fiction   ( marcgt )
 Notes
Bibliography: Includes bibliographical references (p.11-12).
Statement of Responsibility: F.M. Rhoads and S.M. Olson.
General Note: Cover title.
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Bibliographic ID: UF00066130
Volume ID: VID00001
Source Institution: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: oclc - 71188429

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NFREC Res. Rpt. 94-16


SOURCE OF P, LIME APPLICA TION

SEQUENCE, AND

RESIDUAL EFFECTS ON P

A AVAILABILITY TO WA TERMELON



F. M. Rhoads and S. M. Olson


NORTH FLORIDA RESEARCH AND


EDUCA TION CENTER,


UNIVER
FLO]


QUINC Y


Florida Agricultural Experiment Stations
Instititute of Food and Agricultural Sciences
University of Florida Gainesville

SITY OF 4
SIDA ,.


-L IJLA..L -.


SFlorida


Institute of Food and Agricultural Sciences











ABSTRACT

The value of watermelon [Citrullus lanatus (Thunb.) Matsum. &

Nakai] production in Florida was reported at more than $62 million

in 1991-92. Watermelon has a relatively high phosphorus (P)

requirement. Availability of P from triple superphosphate (TSP) to

some crops was reported to be greater than from diammonium

phosphate (DAP). Also, lime and P application sequence was

reported to influence availability of DAP but residual

effects have not been investigated. Our objectives were to

determine the influence of P source and lime and P application

sequence on P availability to watermelon and determine the

availability of residual P with respect to P source and lime

treatment. Two crops of watermelon were grown consecutively in the

same soil in pots containing 2 kg (4.4 lb) of soil each. The first

planting was made in the fall and the second in the spring. The Ap

horizon of a Norfolk loamy sand (fine-loamy, siliceous, thermic,

Typic Kandiudult) containing <5.0 mg kg'' Mehlich-1 extractable P

was used. Rates of P were 40 and 80 mg kg'1 (80 and 160 Ib acre"')

from either TSP or DAP. Calcium oxide was added at a rate of 1 g

kg1' (2000 lb acre"') either 4 wk before or 4 wk after P

application. The experiment consisted of two P sources, two P

rates, three lime treatments and a control with no lime or P added.

There were four replicates and the analysis of variance was

conducted on the 2x2x3 factorial treatment arrangement. Dry-matter

yield and P content of watermelon tissue were determined.

Availability of P from TSP was 23% greater than with DAP in the









first crop (immediate effect) and 14% greater in the second crop

(residual effect), averaged over P rates and lime treatments, as

shown by analysis of variance. Without lime, availability of P was

about 23% greater with TSP than with DAP in both crops. Liming

before P application increased P availability by 17% in the first

crop and by 22% in the second crop over the control (no lime).

Liming after P application decreased P availability by 12% in the

first crop, but it increased P availability by 11% in the second

crop.









In Florida, watermelons are important to the agricultural

economy of the state, having a value of more than $62 million in

1991-1992 (Freie and Young, 1993). Most growers plant their

watermelon crop on land taken out of pasture or on land cleared

prior to planting to avoid plant diseases that reduce yield and

quality. Where soil-test phosphorus (P) is low, about 70 lb acre"'

is recommended for watermelon production (Hanlon et al., 1990).

A total of more than 3 million lb of P would be required for

watermelons in Florida if all 53,000 acres planted in 1991-1992

(Freie and Young, 1993) received 70 lb of P acre'1 Considerable

savings in fertilizer costs could be realized over a period of

several years if growers used the most efficient source of P in

terms of fraction available to plants. Information on the effect

of P source on watermelon response is limited (Locascio et al.,

1968). Effects of lime and P application sequence on P

availability have only been investigated on a limited number of

crops. Therefore, studies showing the influence of lime and P

application sequence on P availability to watermelon and similar

crops were not found in the literature.

Phosphorus availability to snap bean from diammonium phosphate

(DAP) has been shown to be less than from triple superphosphate

(TSP) on an acid coastal plain soil (Rhoads, 1991). Lime and P

application sequence had strikingly different effects on P

availability to snap bean in comparisons between TSP and DAP

(Rhoads et al., 1993). Lime application had no effect on P

availability from TSP, however, lime applied 4 wk before P









increased availability of DAP to a greater extent than lime applied

4 wk after P (69% vs 26%). Other researchers have shown increased

crop growth and/or P availability when lime was applied before P in

comparison to lime applied after P with various sources of P (Singh

and Seatz, 1961; Soltanpour et al., 1974; and Wang and Yuan, 1989).

Phosphorus uptake by plants is used as an index of P availability

in this report.

Objectives of this research were to (1) determine the

influence of P source and sequence of lime and P application on P

availability to watermelon and (2) determine the availability of

residual P with respect to source and lime treatment.



MATERIALS AND METHODS

Two crops of watermelon plants were grown consecutively in the

same soil at Quincy, Florida in greenhouse pots; one during the

fall of 1992 and the second in the spring of 1993. Each pot

contained 2 kg (4.4 lb) of soil material from the Ap horizon of a

Norfolk loamy sand (fine-loamy siliceous, thermic, Typic

Kandiudult) containing <5mg P kg'' (less than 5 parts per million).

Phosphorus sources were triple superphosphate containing 20% P and

diammonium phosphate which contains 23% P and 20% nitrogen (N).

Rates of P were 40 and 80 mg kg'1 (80 and 160 lb acre'). Lime

source was calcium oxide (CaO) applied at the rate of 1 g kg'' (2000

lb acre"1) either 4 wk before P application or 4 wk after P

application. Lime and P were applied only to the first crop as

was 0.25 g of K kg'" (500 lb of K acre-1) of soil as K2SO4 .









Ammonium nitrate was applied to each crop at the rate of 128 mg N

kg'' (256 Ib of N acre"') of soil without regard for the N contained

in DAP.

The cultivar for both crops was 'Crimson Sweet'. Six seeds

were planted in each pot and plants were thinned to 2 per pot after

emergence. The fall crop was planted September 30 and harvested 6

wk later, while the spring crop was planted April 1 and harvested

8 wk later. The longer growing period for the second crop allowed

time for greater expression of residual effects. Before planting

each crop, soil-water content was brought up to 250 mL per 2 kg of

air-dry soil to approximate field capacity. Seed for the first

crop were planted 4wk after water, lime, and P were applied.

During each growing season only 100 mL of tapwater pot"' was added

each time the soil surface was dry to avoid water logged

conditions. Soil was moistend (water content brought up to 250 mL

per 2 kg of air-dry soil) and allowed to dry three times between

crops to simulate wetting and drying cycles that occur in the

field. The purpose of two crops was to show immediate response to

lime and P application in the first and response to residual lime

and P in the second crop.

Both shoots and roots were harvested at the end of each test

and dry-weight was determined after drying to constant weight at

70 OC. One g of ground plant material was ashed at 500 OC and taken

up in dilute HC1. Phosphorus was determined by the molybdenum blue

method. Total P uptake was determined from dry-weight and P

concentration of shoots and roots. Both dry-weight of shoots and









* total P uptake were reported as a percent of the treatment

producing the maximum amount of dry-matter or P uptake in each crop

for convenience in making comparisons between experiments.

The experimental design consisted of a completely randomized

block with treatments arranged factorially in 4 replicates. There

were two P rates, two P sources, and three lime treatments for a

total of 12 treatments plus a control having no lime or P. A three

factor analysis of variance was used to evaluate main effects and

interactions between factors (Steel and Torrie, 1960). The error

mean square (ems) and student's t (2.036) for 33 degrees of freedom

were used to calculate LSD 05g's as follows: LSD=2.036(2ems/24)1/2 for

P sources and P rates, LSD=2.036(2ems/16)1/2 for lime treatments,

and LSD=2.036(2ems/4)1/2 for the twelve individual treatments. The

* control treatment was not used in the analysis of variance

procedures, but was included to show magnitude of P response in

other treatments.



RESULTS AND DISCUSSION

Factors significantly (P s 0.01) influencing plant growth

(dry-matter yield) and total P uptake were P sources, P rate, and

lime treatments (Table 1). The interaction of P rate by P source

influenced both plant growth (P < 0.01) and total P uptake (P <

0.05) but only in the first crop. Interaction between lime

treatment and P source influenced plant growth in both crops but

not total P uptake. Actual maximum yield of the first crop was

about 40% of the maximum for the second crop. Increased yield of









the second crop was attributed to a longer growth period (6 wk vs

8 wk) and longer days in the last part of the growth period

(October vs May).

Plant growth, expressed as percent of maximum, was 21% greater

in the first crop and 13% greater in the second crop with TSP than

DAP, averaged over P rates and lime treatments (Table 2). The P

rate of 80 mg kg'1 produced 26% more dry-weight in both the first

and. second crop than the 40 mg kg'1 rate when averaged over P

sources and lime treatments. Interaction between P sources and P

rates in the first crop is shown by a yield increase of 34% with

TSP and only 18% with DAP between 40 and 80 mg P kg''. A lack of

interaction between P rate and P source in the second crop was

demonstrated by similar yield increases between 40 and 80 mg P kg"

with each P source, i. e. 25% with TSP and 27% with DAP. These

observations indicate that differences in watermelon response

between P sources were less with residual P than with P application

to the immediate crop.

The significant interaction between lime treatments and P

sources indicates that plant response to lime with TSP was

different from that with DAP. Liming the first crop 4 wk before

applying TSP did not significantly (P > 0.05) influence plant

growth compared with no lime (Table 2). However,liming the first

crop 4 wk after TSP application decreased dry-matter yield by

[1/2(62+100-52-87)] 11% (LSD.05= 9.8%). But lime had no effect on

plant growth with TSP in the second crop. Liming 4 wk before DAP

application increased dry-matter yield by [1/2(67+84-41-68)] 21%









(LSDo.05= 9.8%) in the first crop and [1/2(81+99-28-73)] 39% (LSD0.05=
14.2%) in the second crop. However, liming 4 wk after DAP

application reduced dry-matter by [1/2(41+68-36-46)] 14% (LSD005=

9.8%) in the first crop and increased it by [1/2(77+58-28-73)] 17%

(LSD0.05= 14.2%) in the second crop. Therefore, immediate (first
crop) and residual (second crop) effects of both TSP and DAP with

no lime and liming 4 wk before applying P were similar. However,

liming after P application reduced the yield of the first crop with

both TSP and DAP, but the residual response to DAP was positive and

to TSP not significant compared to no lime.

Phosphorus uptake, expressed as per cent of maximum, was 23%

greater in the first crop and 14% greater in the second crop with

TSP than with DAP, averaged over P rates and lime treatments (Table

S 3). The P rate of 80 mg kg-1 increased P uptake of watermelon by

28% in the first crop and 32% in the second crop, averaged over

P sources and lime treatments, in comparison to the 40 mg kg'' rate.

The interaction between P rates and sources in the first crop was

shown by an increase in P uptake of 36% with TSP and only 19% with

DAP between 40 and 80 mg of P kg'. The lack of interaction between

P rates and sources in the second crop was demonstrated by similar

increases in P uptake between 40 and 80 mg P kg'1 with each P

source, i.e. 34% with TSP and 31% with DAP. Therefore, we

conclude that DAP with lime was considerably more

[1/4(63+88+47+72-47-70-22-30)=25%] available to watermelon in the

second crop (residual effect) than in the first crop. Also, there

was a small overall increase (10%) between crops in availability of









residual TSP.

Unlike dry-matter response, there was no interaction between

lime treatments and P sources on P uptake of watermelon. Liming 4

wk before P application increased P uptake by 17% (LSD0g05= 8.3%) in

the first crop and by 22% (LSD0.05= 11.3%) in the second compared to

no lime. Response to liming 4 wk after P application was different

between the first and second crop. Liming after P application in

the first crop reduced P uptake 12% (LSD.05= 8.3%), however,

residual (second crop) lime after P increased P uptake 11% (LSDo.05=

11.3%) compared to no lime, although the increase was not

significant.



CONCLUSIONS

Availability of TSP was 23% greater than DAP in the first crop

and 14% greater (significant at P 0.01, Table 1.) in the second

crop, averaged over P rates and lime treatments. The data indicate

that liming 4 wk before P application increased the availability

of P from both P sources. Liming after P application decreased P

availability in the first crop and increased it in the second crop.

Furthermore, liming after P application in the first crop decreased

P availability more with DAP than TSP. The difference between TSP

and DAP in P availability did not change between the first and

second crop with no lime. However, liming either before or after

P application had a tendency to reduce the difference in

availability of residual P between TSP and DAP.

If cost per unit of P is the same, TSP appears to be superior









Sto DAP on acid soils. However, if DAP has cost advantage and soil

pH is below 6.0, lime application several weeks before P

application will make P availability from DAP about equal to that

of TSP. Cost of DAP, TSP, and lime should be considered when

deciding which P source to use.



REFERENCES

Freie, R. L., and H. V. Young, Jr. 1993. Vegetable summary 1991-

1992, Florida Agricultural Statistics. Florida Department of

Agriculture and Consumer Services, Orlando.

Hanlon, E. A., G. Kidder, and B. L. McNeal. 1990. Soil, container

media, and water testing; interpretations and standardized

fertilization recommendations. Florida. Coop. Extension

Serv., Univ. of Florida, Gainesville. Circular 817. 49 pp.

Locascio, S. J., P. H. Everett, and J. G. A. Fiskell. 1968. Effects

of phosphorus sources and copper rates on watermelons. Proc.

Am.Soc. Hort. Sci. 92:583-589.

Rhoads, F. M. 1991. Phosphorus source, soil-test P, snap bean

growth, and P uptake. Soil Crop Sci. Soc. Florida Proc.

50:122-124.

Rhoads, F. M., E. A. Hanlon, and S. M. Olson. 1993. Phosphorus

availability to snap beans as affected by lime sequence and

phosphorus source. Soil Crop Sci. Soc. Florida Proc. 52:90-

94.

Singh, R. N. and L. F. Seatz. 1961. Alfalfa yield and composition

after different times and rates of lime and phosphorus









application Soil Sci. Soc. Am. Proc. 25:307-309.

Soltanpour, P. E., F. Adams, and A. C. Bennett. 1974. Soil

phosphorus availability as measured by displaced soil

solution, calcium-chloride extracts, dilute-acid extracts, and

labile phosphorus. Soil Sci. Soc. Am. Proc. 38:225-228.

Steel, R. G. D., and J. H. Torrie. 1960. Principles and Procedures

of Statistics. McGraw-Hill, New York. 481 pp.

Wang, H. D. and T. L. Yuan. 1989. Lime effects on phosphorus

retention and release in four Ultisols. Soil Crop Sci. Soc.

Florida Proc. 48:131-137.









* Table 1. Calculated F values from analysis of variance procedures

for shoot dry-weight and phosphorus uptake of watermelon plants.

Shoot dry-weight P uptake

Source df First crop Second crop First crop Second crop

Replication 3 0.57 3.52* 2.49 0.49

P source (A) 1 56.95** 10.58** 47.53** 10.44**

P rate (B) 1 84.94** 42.05** 69.76** 51.84**

AB 1 8.76** 0.09 6.33* 0.12

Lime (C) 2 24.69** 12.60** 25.10** 7.78**

AC 2 5.73** 4.28* 0.47 1.33

BC 2 1.42 1.67 1.68 .0.15

ABC 2 0.73 0.86 0.74 0.88

Error 33

* *, ** = Significance at 0.05 and 0.01, respectively.









Table 2. Dry-matter yield of watermelon shoots for two crops grown

in the same soil with application of phosphorus and lime to the

first crop only. Sources of phosphorus were triple superphosphate

(TSP) and diammonium phosphate (DAP)


Lime

P rate Rate Timet

mg kg'' g kg'1

0 0 -

40 0

80 0

40 1 L-P

80 1 L-P

40 1 P-L

80 1 P-L

LSDO.


Dry-matter yields

First crop Second crop

TSP DAP TSP DAP

% of maximum

11 11 6 6

62 41 63 28

100 68 91 73

69 67 75 81

98 84 100 99

52 36 72 58

87 46 94 77

13.9 13.9 20.1 20.1


t L-P = Lime incubated in soil 4 wk before P application and P-L =

P incubated in soil 4 wk before lime application.

$ The treatment in each crop that produced the highest yield was

given the value of 100%.









S Table 3. Total phosphorus uptake of watermelon plants for two

crops grown in the same soil with application of P and lime to the

first crop only. Sources of P were triple superphosphate (TSP) and

diammonium phosphate (DAP).


Lime

Rate Timet

g kg''

0 --


L-P

L-P

P-L

P-L
P-L


LSDo.5


Phosphorus uptaket

First crop Second crop

TSP DAP TSP DAP


% of maximum

3 3 6 6

47 26 53 23

80 53 82 66

54 47 62 63

100 70 100 88

37 22 57 47

67 30 92 72

16.7 16.7 22.5 22.5


t L-P = Lime incubated in soil 4 wk before P application and P-L

= P incubated in soil 4 wk before lime application.

$ The treatment in each crop that had the highest P uptake was

given the value of 100%.


P rate

mg kg''

0

40

80

40

80

40

80


TSP DAP TSP DA











)




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