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Agriculture

Southern Forest

Experiment Station

Research Noteso-31 9

November 1985

Oak Seeding on an Adverse Field Site

Robert L. Johnson and Roger M. Krinard

SUMMARY

Direct-seeded Nuttall oak (Quercus nutiallii Palmer)

and water oak (Q. nigra L.) acorns on an old-field site of

Sharkey clay soil typifying marginal crop production sites

gave a first-year seedling percentage of 55 and 49, respectively. Seedling percentage of acorns sown at a

2-inch depth was greater than that of acorns sown at 4-

and 6-inch depths (63 vs. 47 and 46 percent).

Additional keywords: direct seeding, germination,

Nuttall oak (Quercus nutiallii), old-field sites, water oak

(Q. nigra).

INTRODUCTION

During the last 30 years (1955-85), millions of bottomland acres have been cleared of natural hardwood forest

and planted to various agricultural crops, particularly

soybeans. Some such areas have very poorly drained

clay soil subject to growing season drought. At best, they

have been marginal for crop production.

Several thousand acres of marginal fields are either

being restored or are planned for restoration to trees,

primarily by public agencies. Technology to successfully

plant such areas with suitable bottomland hardwood

species is available. However, recent work in cleared

forested areas on both bottomland sites and brown loam

uplands indicates that there may be another less expensive, and perhaps more flexible option-direct sowing of

acorns (Johnson 1981, 1983, 1984). This method of

direct-seeding acorns was tested during 1984 on a representative old-field site, and the results are reported

herein. Also, water oak acorns were included for the first

time along with Nuttall oak acorns.

STUDY AREA

The study area, located near Greenville, Mississippi,

was a field that had been farmed for 15 to 20 years

(fig. 1). The soil is poorly drained, essentially flat

Sharkey clay having 12 percent sand, 75 percent clay,

13 percent silt, and a pH of 6.0. The Sharkey series is a

member of the very fine montmorillonitic, nonacid, thermic family of Vertic Haplaquepts and has an average site

index, at 50 years, of 91 and 85 feet for Nuttall oak

(Quercus nuttallii Palmer) and water oak (Q. nigra L.),

respectively (Broadfoot 1976).

Milo was grown the summer before direct seeding, but

in most years the crop had been soybeans and returns

were nominal. Through the previous 6 years, for example, there were two total crop failures, one due to drought

and the other to growing-season flooding. ‘The best crop

yielded only 18 to 20 bushels of soybeans per acre, with

a net return for the owner of $22.00/acre. In general, the

characteristics and productivity of the study site are similar

to those of many sites being considered for reforestation.

METHODS

Acorns were collected from three Nuttall oak and three

water oak trees. Parent trees were selected to provide a

range of acorn sizes-496, 400, and 280 acorns per

gallon for the Nuttall and 1,556, 1,340, and 1,248 per

gallon for the water oak. After a float test, sample acorns

from non-floaters were cut and examined or germinated

in the laboratory. The remaining acorns were stored at

35” to 40” F in polyethylene bags for about 3 months.

Within species, .experimental design was a randomized complete block with nine treatments and four

blocks. One combination of three sowing depths, 2, 4,

and 6 inches, with one of three parent trees (acorn

sizes), was assigned at random to each row within a

Southern Forest Experiment Stationfl-10210 U.S. Postal Services Bldg., 701 Loyola Avenue, New Orleans, La. 7Oll3

Forest Service, U.S. Department of Agriculture.

Serving Alabama, Arkansas, Louisiana, Mississippi, E. Oklahoma, Tennessee, E. Texas, Puerto Rico, U.S. Virgln Islands

1
Figure 1 .-General view of planting area in February 1984 (top), with flags marking sowing spots, and

in August 1984 (bottom) showing vegetative competition.

Robed L. Johnson is Principal Silviculturist and Roger M. Krinard is Mensurationist at the Southern Hardwoods Laboratory, maintained at Stoneville,

Mrssissrppi, by the Southern Forest Experiment Station, Forest Service-USDA, in cooperation with the Mississippi Agricultural and Forestry

Experiment Station and the Southern Hardwood Forest Research Group.

2
block. For analyses, germination was summed over

sizes for each depth, reducing the number of treatments

to three. Between species, species were completely random major plots in a split-plot design, with minor plots

being depth treatments.

Rows were spaced 10 feet apart, seed spots 4 feet.

Three acorns were hand-sown in 50 seed spots per row

in early February. Additional acorns of each treatment

combination were sown for biweekly destructive samples. Randomly selected rows of each treatment combination were checked biweekly for germination.

Twice during the first year, on May 5 and September

12, strips between rows were bush-hogged in one direction.

RESULTS

Cutting and germination tests after seed collection

showed that over 80 percent of the acorns from each

tree were sound and viable.

On April 2, or about 7 weeks after sowing, destructive

sampling showed that large water oak acorns were deteriorating; many subsequent sample acorns were dead,

reflecting the condition of the test population, which essentially failed to produce seedlings. Sample acorns

from other parent trees germinated in a normal fashion.

Moisture contents of ungerminated, field-sown water

oak acorns in March and April averaged 58 or 59 percent

(based on oven-dry weight), while small, medium, and

70

6 0

large Nuttall oak acorns averaged 73,80, and an unusually high 124 percent, respectively.

Final seedling percentage (No. seedlings/No. acorns

sown) was 55 for Nuttall oak and 35 for water oak-if

large acorns are considered-and 55 vs. 49 if they are

not. Nuttall emerged 2 weeks earlier than water oak and

germinated faster. Two-thirds of the Nuttall oak had germinated by mid-June and over 90 percent by late July.

About one-third of the water oak germinated in June,

one-third in July, and the rest in August and September.

Sowing depth affected seedling percentages for both

species (table 1). Two-inch-deep acorns had a seedling

percentage of 54 compared to 40 for those planted 4 and

6 inches deep. Excluding large acorns, 2-inch-deep

water oak had 63 percent germination and the deeper

ones 46 percent. Germination started at about the same

time from all three depths; rate of emergence was similar

for 2- and 4-inch-deep acorns but initially lagged for

those planted 6 inches deep (fig. 2). The percentage of

Table 1 .-Seedling percentage for Nuttall and water oak acorns

Depth

Nuttall Water

oak oak Average

inches _ _ _ _ _ _ _ _ _ _ - _ _ - _ _ - percent _ _ _ _ _ - _ _ _ _ _ _ _ _ - _

2 6 5 4 3 5 4

4 5 1 3 2 4 1

6 5 0 3 0 4 0

Average 5 5 3 5 4 5

5124 6/5 6/18 7/2 711-f 7130 S/l5 8/27 9114 S/26 IO/IO IO/31

DATE

Figure P.-Percentage of seedlings from Nuttall oak (NO) and water oak (WO) acorns planted at 2-, 4;

and 6-inch depths.

3
seed spots with one or more seedlings was higher for the

2-inch sowing depth, 92 vs. 82 and 83 for the 4- and

6-inch depths for Nuttall oak and 69 vs. 63 and 57 for

water oak.

By fall, Nuttall oak seedlings, tallest per seed spot,

were more than twice the size of water oak, 0.56 vs. 0.26

foot. Averaged over species, seedling heights by sowing

depths were 2 inches > 4 inches > 6 inches, although

actual differences between depths were less than 0.1

foot.

CONCLUSIONS

Direct sowing of Nuttall and water oak acorns is one

way to establish trees on recently farmed, poorly drained

Sharkey clay fields. Acorns can be sown as deep as 6

inches, but 2 inches gives better results. Acorns germinate throughout the summer, so results of direct seeding

should be evaluated late in the growing season.

Visual examination of cut acorns, float tests, and even

germination tests may not accurately predict the field

germinability of some seed lots, as was demonstrated by

the large water oak acorns.

LITERATURE CITED

Broadfoot, Walter M. Hardwood suitability for and properties of important Midsouth soils. Research Paper

SO-127. New Orleans, LA: U.S. Department of Agriculture, Forest Service, Southern Forest Experiment

Station; 1976. 84 p.

Johnson, Ft. L. Oak seeding-it can work. Southern

Journal of Applied Forestry 5(l): 28-33; 1981.

Johnson, Robert L. Nuttall oak direct seedings still successful after 11 years. Research Note SO-301. New

Orleans, LA: U.S. Department of Agriculture, Forest

Service, Southern Forest Experiment Station; 1983.

3 P.

Johnson, R. L. Direct-seeded cherrybark and Shumard

oaks battle natural regeneration through 10 years.

Southern Journal of Applied Forestry 8(4): 226-231;

1984.