,a United States ii& Department of

Agriculture

Forest Service

Southern Forest

Research Note

so-379

Experiment Station September 1995

Responses of Young Slash Pine on Poorly Drained to

Somewhat Poorly Drained Silt Loam Soils to Site Preparation

and Fertilization Treatments

James D. Haywood

SUMMARY

Slash pines (Pinus elliottii Engelm. var. e//iottil) were

planted on poorly drained Wrightsville and somewhat

poorly drained Vidrine silt loam soils in southwest Louisiana. Neither flat disking nor bedding increased pine

growth and yield substantially after nine growing seasons, but broadcast application of triple superphoshate

increased pine productivity on both soil types. On the

Vidrine soil, slash pine diameter at breast height (d.b.h.),

total height, volume per tree, and volume per acre averaged 4.4 inches, 24 ft, 1.7 ft3, and 890 ft3/acre, respectively, over all treatments. On the Wrightsville soil, values

of these variables averaged 3.8 inches, 19 ft, 1 .O ft3, and

350 fts/acre, respectively, over all treatments. The incidence of fusiform rust galls on the main stem, which are

caused by Cronartium quercuum (Berk.) Miyabe ex Shirai

f. sp. fusifofme, averaged 28 percent across both soils,

which is below average for slash pine in the West Gulf

Coastal Plain.

INTRODUCTION

Slash Pine (Pinus elliotiii Engelm. var. e//iottil) grows

well on poorly drained to somewhat poorly drained soils

in the lower Coastal Plain (Shoulders 1976). Slash pine

performs better than loblolly pine (P. taeda L.) on these

soils, especially in repeated rotations on unfertilized sites

(Haywood 1994, Haywood and others 1990). Fusiform

rust, which is caused by Cronartium quercuum (Berk.)

Miyabe ex Shirai f. sp. fusitbrme, causes mortality and

degrade in slash pine plantations, reducing timber values and income (Anderson and others 1986, Busby and

Haines 1988, Webb and Patterson 1984). Intensive cultural practices that increase the growth of slash pine

seedlings may also increase the incidence of fusiform

rust (Dinus and Schmidtling 1971, Tiarks 1983). However, when slash pine planting stock is resistant to fusiform rust, applications of phosphorus and nitrogen

fertilizers may greatly increase yields on phosphorusdeficient soils (Haywood and others 1994, Shoulders and

Tiarks 1990, Tiarks and Shoulders 1982).

In this study, slash pines were planted on poorly

drained and somewhat poorly drained silt loams with and

without phosphorus fertilization, disking, and bedding to

determine the growth response of slash pine to amelioration on soils with poor internal drainage. After 6 years,

the fertilizer treatment was ‘ineffective on the poorly

drained Wrightsville soil but was effective on the somewhat poorly drained Vidrine soil (Haywood 1983a). However, phosphorus fertilization may not significantly affect

the growth of pine trees for many years (Tiarks 1983).

After 9 years, the fertilizer treatment was effective on

both soils.

STUDY AREA

The 14-acre study area in Calcasieu Parish, Louisiana, previously supported a natural stand of longleaf pine

(P. palustris Mill.). A dense cover of native grasses, scattered southern bayberry or waxmyrtle (Myrica cerifera

L.), and blackberry (Rubus spp.) were in the understory.

The soil is a Wrightsville (Typic Glossaqualf, fine,

mixed, thermic) and Vidrine (Glossaquic Hapludalf,

coarse-silty over clayey, mixed, thermic) silt loam complex with a general slope of 0 to 1 percent (Haywood

1983a). Many solitary “pimple mounds” of Vidrine soil

occupy about 16 percent of the area. The upper foot of

these mounds is generally well drained, but both soil

Southern Forest Experiment Station/T-l 0210 U.S. Postal Services Bldg., 701 Loyola Avenue, New Orleans, La. 70113

Forest Service, U.S. Department of Agriculture.

Servlng Alabama, Arkansas, Louisiana, Mississippi, E. Oklahoma, Tennessee, E. Texas, Puerto Rico, U.S. Virgin Islands.

1
moisture and yellowish brown mottling increase with

depth. A less permeable silty clay subsoil with distinct

red mottling generally begins at a depth of 30 inches

and slopes downward from under the mound, reaching

its greatest depth under the Wrightsville silt loam depressions. A perched water table rests above the subsoil for

2 to 4 months in winter and spring. Vidrine-like silt loam

occupies 49 percent of the area, surrounds the mounds,

and may form ridgesconnecting them. This soil is not as

well drained as the Vidrine soil of the mounds. Wrightsville

silt loam occupies 35 percent of the area. It forms unconnected, meandering swales between the Vidrine

mounds and Vidrine-like ridges, and these swales contain standing water during winter.

METHODS

The longleaf stand was clearcut harvested in 1971,

and residual vegetation and logging debris were burned

in September 1972. In October 1972, two fertilization and

three site-preparation treatments were laid out in a randomized complete block 2 x 3 factorial design. There

were four blocks, and each block contained six plots. Each

plot was 0.4 acres in size. The two fertility levels were (1)

unfertilized and (2) fertilized by broadcasting 500 lb of

triple superphosphate per acre (101 lb P/acre) before

mechanical treatment. The three site-preparation levels

were: (1) no additional treatment after burning in September 1972, (2) burned and disked, and (3) burned,

disked, and bedded. Treatments 2 and 3 were disked

with a harrow, and the continuous beds in treatment 3

were formed using a bedding harrow equipped with a

shaping roller.The beds were parallel to the general slope

of the site. Bed centers were 10 inches high (furrow to

crest) before settling and were spaced 8 ft apart.

Therefore, within each block the six combinations of

treatments were as follows:

(1) burned only

(2) burned and disked

(3) burned, disked, ‘and bedded

(4) burned and fertilized with triple superphosphate

(5) burned, disked, and fertilized with triple superphosphate

(8) burned, disked, bedded, and fertilized with triple

superphosphate

Freshly lifted bare-root 1-O slash pine seedlings were

uniformly graded and planted by hand on an 8-ft by 8-ft

spacing in late February 1973. Two seedlings were

planted at each location. If both survived, the less vigorous one was removed after two growing seasons.

After four growing seasons, each planting site within

each 0.4-acre plot was assigned to one of two topography classes because soil drainage seemed to be influencing results more than the study treatments were.The

topography classes were: (1) somewhat poorly drained

Vidrine mounds and Vidrine-like ridges and (2) poorly

drained Wrightsville depressions.

Survival and fusiform rust incidence were surveyed

after five growing seasons. After nine growing seasons,

slash pine survival, diameter at breast height (d.b.h.),

total height, and the presence or absence of fusiform

rust galls on the main stem were determined. Cubic-foot

volumes of trees at least 4.5 ft tall were calculated using

Lohrey’s (1985) formula.

Data for the two topographic classes were analyzed

separately because interaction between topographic

classes and whole plot factors made it impractical to use

a split-plot design with topographic classes as the subplot treatments to determine the influences of fertilization and site preparation on slash pine growth and yield.

Each plot had sufficient numbers of planting locations in

each topographic class, so no plots were excluded from

the analyses. The number of planting locations on

Wrightsville soil ranged from 44 to 138 per plot, and the

number on Vidrine or Vidrine-like soil ranged from 138

to 228 per plot.

The survival, height, d.b.h., volume, and fusiform rust

data for each topographic class were analyzed by analysis of variance (alpha = 0.05). The significance of mean

differences associated with the two main effect levels

(fertilization and site preparation) and the fertilization by

site preparation interactions were determined by orthogonal trend comparisons.

RESULTS AND DISCUSSION

Vidrine Soils

Bedding did not influence slash pine survival, growth,

and yield through nine growing seasons on the somewhat poorly drained Vidrine mounds and Vidrine-like

ridges (table 1). Planting site occupancy averaged 78

percent and was this high partly because of the double

planting. Across all fertilization and site preparation treatments, pine d.b.h., total height, volume per tree, and

volume per acre averaged 4.4 inches, 24 ft, 1.7 ft3, and

890 ft3/acre, respectively.

Long-term responses of slash pine to mechanical site

amelioration are often not statistically significant on somewhat poorly drained silt loam soils (Haywood 1980,

James D. Haywood is a silviculturist at the Alexandria Forestry Center, U.S. Department of Agriculture, Forest Service, Southern Forest Experiment Station, Pineville, LA 71360.

2
Table 1.--Ninth-year results for slash pine (Pinus elliottii Engelm. var. elliottii) planted on somewhat

poorly drained Vidrine mounds and Vidrine-like ridges

Site preparation and

fertility combinations Survival D.b.h.

Total

height

Volume

Per tree Per acre

Fusiform

infection

Burned only*

Fertilized

Unfertilized

Mean

Percent

7 5

8 1

78t

Burned and disked

Fertilized

Unfertilized

Mean

7 8 5.1 28.4 2.34 1,243 2 6

8 0 3.8 21.6 1.17 637 3 1

7 9 4.4 24.0 1.75 940 2 8

Burned, disked, and bedded

Fertilized

Unfertilized

Mean

7 3 4.9 26.1 2.19 1,089 3 1

8 0 3.9 21.4 1.17 637 3 0

7 8 4.4 23.8 1.68 863 3 1

All site preparation treatments

Fertilized

Unfertilized

Mean of means

75b*

80a

7 8

Inches ft

5.1 28.2 2.33 1,190 3 1

3.7 20.4 0.99 546 2 8

4.4 23.3 1.86 868 2 9

5.0a

3.8b

4.4

26.2a

21.lb

23.7

2.29a

l.llb

1.70

1,174a

607b

890

Percent

29a

30a

2 9

‘Number of planting locations classed as the somewhat poorly drained Vidrine mounds and Vidrinelike ridges ranged from 136 to 228 per plot. Two trees were planted per location, and if both survived,

the less vigorous one was removed after the second growing season.

%Qthin columns, none of the site preparation treatment means was significantly different (alpha =

0.05).

*Within columns, means for the two fertilization levels followed by the same letter are not significantly different (alpha = 0.05).

1983b). In some instances, growth responses of slash

pine seedlings to mechanical site amelioration disappear

once the trees are 10 to 15 years old (Tiarks 1983). In

these studies, early added pine growth following mechanical site amelioration is attributed to competition

control, increased fertility resulting from mixing of organic

matter into the soil, and improved soil aeration.

A broadcast application of triple superphosphate before mechanical site preparation reduced slash pine survival but significantly increased d.b.h., total height, volume

per tree, and volume per acre by 32, 24, 106, and 93

percent, respectively (table 1). The fertilizer was mixed

into the soil on the disked and bedded plots but was left

on the surface of the burned-only plots. The way in which

the fertilizer was applied apparently had no effect on tree

growth, and incorporation of phosphorus fertilizers had

not been necessary in other studies (Haywood and others 1994, Shoulders and Tiarks 1990). It is likely that

there will be greater differences between growth in the

fertilized and unfertilized plots in later years (Tiarks 1983).

Wrlghtsvllle Soil

Both mechanical site preparation and fertilization reduced slash pine survival in the poorly drained Wrightsville depressions (table 2). After bedding, the soils settled

for only 4 months before planting, and this period is often insufficient for poorly drained silt loams (Haywood

1983a).There were probably too many air pockets in the

soil during the first growihg season following planting.

Certain combinations of fertilization and site preparation influenced slash pine growth and yield more strongly

than others (table 2). Mean d.b.h., total height, volume

per tree, and volume per acre in the burned, disked, bedded, and fertilized plots were 25,24,74, and 48 percent

greater, respectively, than the corresponding mean of

means over all treatments. Mean d.b.h., total height, volume per tree, and volume per acre in the burned and

fertilized plots were 14, 11, 35, and 45 percent greater,

respectively, than the corresponding mean of means over

all treatments.

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Table 2.-Ninth-year results for slash pine (Pinus elliottii Engelm. var. elliottii) planted in the poor/y

drained Wrightsville depressions

Site preparation and

fertility combinations Survival D.b.h.

Total

height

Volume

Fusiform

Per tree Per acre infection

Burned only”

Fertilized

Unfertilized

Mean

Burned and disked

Fertilized

Unfertilized

Mean

Burned, disked, and bedded

Fertilized

Unfertilized

Mean

Percent Inches Ft

5 4 4.1t 21.4t

6 7 2.8 15.5

60a* 3.4 18.4

4 2 3.6 18.8

5 5 3.0 17.2

40b 3.3 18.0

4 3 4.5t 24.0t

5 9 3.4 18.9

51b 4.0 21.4

All site preparation treatments

Fertilized

Unfertilized

Mean of means

46bs 4.1 21.4

60a 3.1 17.2

5 3 3.6 19.3

__________j=f3 __________

1.38t 507t

0.47 214

0.92 360

1.05 300

0.65 243

0.85 272

1.77t 518t

0.80 321

1.29 419

1.40 439

0.64 260

1.02 350

Percent

34t

2 1

2 8

2 0

2 5

2 2

2 3

35t

2 9

2 5

2 7

2 6

‘Number of planting locations classed as depressions ranged from 44 to 136 per plot. Two trees

were planted per location, and if both survived, the less vigorous one was removed after the second

growing season.

tValues differ significantly from all other values in the same column (alpha = 0.05).

*Within columns, site preparation treatment means followed by the same letter are not significantly

different (alpha = 0.05).

§Within columns, means for the two fertilization levels followed by the same letter are not significantly

different (alpha = 0.05).

On silt loam soils where the mean depth to free water

is less than 18 inches after winter rains, bedding improves

aeration, increases soil drainage, and adds enough welldrained soil to increase slash pine tree growth (Haywood

and others 1990). However, even when beds are laid out

parallel to the general slope of the site, bedding can disrupt the natural drainage pattern on gently rolling silt loam

soils. In these instances, water collects in depressions

and affects tree development adversely. Probably because surface drainage was blocked naturally or artificially, bedding was not effective on the Wrightsville soil

in this study. Although the burned, disked, bedded, and

fertilized treatment combination gave the best results after

nine growing seasons, the burned and fertilized treatment combination produced similar results. It would be

difficult to recommend the added expense of disking and

bedding in addition to the broadcast application of triple

superphosphate.

To conclude, mechanical site preparation treatments

were of little benefit on soils in either topographic class,

but the broadcast application of triple superphoshate had

positive long-term effects on slash pine growth regardless of soil drainage. The use of fertilizers containing

phosphorus is a recommended practice on other soils

as well (Haywood and others 1994, Shoulders and Tiarks

1990, Tiarks 1983).

Fusiform Rust

Percentages of rust infection have been increasing in

slash pine stands in the West Gulf Coastal Plain (Hunt

and Lenhart 1986). In this study, topographic class had

little influence on the incidence of main-stem fusiform

rust galls in surviving trees. After the fifth (data not shown)

and ninth growing seasons, rust incidences averaged 22

and 28 percent, respectively (tables 1 and 2). However,

the levels of infection observed in this study were low for

slash pine in this region, probably because removal of

the least healthy 2-year-old seedlings at each planting

4
location favored seedlings that were initially free of fusiform rust.

Practices that increase pine growth may also increase

the incidence of fusiform rust in slash pine plantings

(Dinus and Schmidtling 1971, Tiarks 1983). Rust-related

mortality can be significant in slash pine stands growing

on silt loam soils, and fresh terminal leaders may develop new rust galls throughout the life of the stand

(Haywood and others 1994). This would explain why the

percentage of gall infections increased between the fifth

and ninth growing seasons, whereas slash pine survival

across both topography classes decreased from 79 to

89 percent (survival averages were weighted for differences in total number of planting locations within each

topographic class).

LITERATURE CITED

Anderson, Robert L.; McClure, Joe P.; Cost, Noel; Uhler,

Robert J. 1986. Estimating fusiform rust losses in five

Southeast States. Southern Journal of Applied Forestry. 10: 237-240.

Busby, Rodney L.; Haines, Terry K. 1988. Determining

the value of a fusiform rust-infected stand. Res. Pap.

SO-245. New Orleans, LA: U.S. Department of Agriculture, Forest Service, Southern Forest Experiment

Station. 5 p.

Dinus, R.J.; Schmidtling, R.C. 1971. Fusiform rust in

loblolly and slash pines after cultivation and fertilization. Res. Pap. SO-68. New Orleans, LA: U.S. Department of Agriculture, Forest Service, Southern Forest

Experiment Station. 10 p.

Haywood, James D. 1980. Planted pines do not respond

to bedding on an Acadia-Beauregard-Kolin silt loam

site. Res. Note SO-259. New Orleans, LA: U.S. Department of Agriculture, Forest Service, Southern Forest Experiment Station. 4 p.

Haywood, James D. 1983a. Small topographic differences affect slash pine response to site preparation

and fertilization. Southern Journal of Applied Forestry.

7: 145-148.

Haywood, James D. 1983b. Response of planted pines to

site preparation on a Beauregard-Caddo soil. In: Jones,

Earle P, Jr., ed. Proceedings of the second biennial southern silvicultural research conference; 1982 November 4-

5; Atlanta, GA. Gen. Tech. Rep. SE-24. Asheville, NC:

U.S. Department of Agriculture, Forest Service, Southeastern Forest Experiment Station: 14-l 7.

Haywood, James D. 1994. Early growth reductions in

short rotation loblolly and slash pine in central Louisiana. Southern Journal of Applied Forestry. 18: 35-39.

Haywood, James D.;Tiarks, Allan E.; Shoulders, Eugene.

1990. Loblolly and slash pine height and diameter are

related to soil drainage in winter on poorly drained silt

loams. New Forests. 4: 81-96.

Haywood, James D.; Tiarks, Allan E.; Snow, Glenn A.

1994. Combinations of fungicide and cultural practices

influence the incidence and impact of fusiform rust in

slash pine plantations. Southern Journal of Applied

Forestry. 18: 53-59.

Hunt, Ellis V.; Lenhart, J. David. 1986. Fusiform rust

trends in east Texas. Southern Journal of Applied Forestry. 10: 215-216.

Lohrey, Richard E. 1985. Stem volume, volume ratio, and

taper equations for slash pine in the West Gulf Region. In: Shoulders, Eugene, ed. Proceedings of the

third biennial southern silvicultural research conference; 1984 November 7-8; Atlanta, GA. Gen. Tech.

Rep. SO-54. New Orleans, LA: US. Department of

Agriculture, Forest Service, Southern Forest Experiment Station: 451-459.

Shoulders, Eugene. 1976. Site characteristics influence

relative performance of loblolly and slash pine. Res.

Pap. SO-1 15. New Orleans, LA: U.S. Department of

Agriculture, Forest Service, Southern Forest Experiment Station. 16 p.

Shoulders, Eugene; Tiarks, Allan E. 1990. Nine-year response of thinned slash pine to nitrogen, phosphorus,

and potassium. Soil Science Society of America Journal. 54: 234-237.

Tiarks, Allan E. 1983. Effect of site preparation and fertilization on slash pine growing on a good site. In:

Jones, Earle P., Jr., ed. Proceedings of the second

biennial southern silvicultural research conference;

1982 November 4-5; Atlanta, GA. Gen.Tech. Rep. SE24. Asheville, NC: U.S. Department of Agriculture,

Forest Service, Southeastern Forest Experiment Station: 34-39.

Tiarks, A.E.; Shoulders, E. 1982. Effects of shallow water tables on height growth and phosphorus uptake by

loblolly and slash pines. Res. Note SO-285. New Orleans, LA: U.S. Department of Agriculture, Forest Service, Southern Forest Experiment Station. 5 p.

Webb, R.S.; Patterson, H.D. 1984. Effect of stem location of fusiform rust symptoms on volume yields of

loblolly and slash sawtimber. Phytopathology. 74: 980-

983.