The Bugwood Network

Fertilizer Recommendations for Enhancing Pine Straw Production

David Dickens - Assistant Professor of Forest Productivity,
David Moorhead - Professor of Silviculture,
Larry Morris - Professor of Forest Soils.

Introduction

Pine straw, the uppermost forest floor layer of recently fallen undecayed reddish-brown pine needles, is raked, baled, and sold as a mulch and for landscaping in the SE US. An estimated $15.5 million in pine straw revenues were realized by forest landowners in Georgia in 1999 (Doherty and others 2000). Generally loblolly (Pinus taeda), longleaf (Pinus palustris), and slash (Pinus elliottii var. elliottii) are the three southern pine species raked for pine straw. Currently the reference is for longleaf, then slash, then loblolly needles. Longer needle length, color retention, and rate of deterioration are factors for this order of reference. Pine straw can be sold by the forest landowner by the bale or by the acre. Current per bale landowner prices are $0.50 to $1.00 for longleaf, $0.50 to $0.60 for slash, and $0.25 to $0.30 for loblolly. Per acre prices can range from $35 to $300 per rake depending on the species, time since last rake, amount of straw, stand access, and site cleanliness. Loblolly is often overlooked in the native range of slash pine (lower Coastal Plain of Georgia into central Florida, and west in the Gulf Coastal Plain to East Louisiana).

When pine straw was first raked in the 1960's and 1970's, only clean portions of stands were worked. More recently, crews and pine straw contractors will clean up loblolly, longleaf and slash pine stands with herbicides, mowing, chipping, piling and/or burning to facilitate raking over the majority of the site. A stand, depending on growth rate, species, and stocking/spacing may first be raked between ages 5- to 10-years-old, usually at or soon after canopy closure. The first rake can often produce a large quantity of straw, depending on site productivity, species, stocking, and age, between 100 to 450 bales/acre. Peak pine straw production in an unraked stand increases almost linearly with increasing basal area (Morris and others 1992). Raking can occur annually, semi-annually, bi-annually, or on infrequent intervals. If raking occurs annually, pine straw production rates can decline at some point, usually after the 3rd or 4th rake. Fertilization and good weed control can enhance the amount of pine straw produced and the portion of the stand that can be raked, respectively. This paper will discuss fertilization recommendations (frequency, timing, dosage) by species and age.

Effects of Raking on Stand Growth, Straw Production, and Water Stress with and without Fertilization

A study addressing the effects of raking and fertilization was conducted in an old-field slash pine stand between ages 8- and 13-years-old in Clay County, Florida (Lopez-Zamora and others 2001). A total of 500 lbs/ac of diammonium phosphate (DAP) was split applied to ½ the plots at age 9-years-old (August 1991) and again at age 10-years-old (September 1992). Raking regimes were: no-rake, annual rake, bi-annual rake, and rake every 4-years. The second ½ plots were unfertilized over the study period. The soils were mapped in the area as Manderin and Hurricane (sandy Typic Haplohumods, and Grossarenic Entic Haplohumods, respectively). Diameter, total height, and bale/acre production rates were followed through age 13-years-old. Lopez-Zamora and others (2000) concluded the following: (1) raking every year significantly reduced diameter growth by 0.20 inches (Table 1), (2) during a single year maximum pine straw production was 298 bales/acre for the annual rake, 378 bales/acre for the rake every other year, and 443 bales/acre for the rake every four years, (3) pine straw phosphorus (P) concentrations were lower in the raked annually plots, (4) fertilization significantly increased nitrogen (N) concentration in the pine straw, (5) soil available phosphorus was significantly higher in the rake every 4-years followed by the control when compared to the rake annually plots, (6) up to 45 lbs N and 4.5 lbs P/acre were removed by raking the pine straw annually (Table 1), (7) fertilization with a total of 90 N and 100 lbs elemental-P did not significantly increased diameter or height growth over the 4-year study period on this highly fertile old-field site, and (8) pitch canker and fusiform rust incidence increased significantly in the fertilized plots. Mortality was highly correlated to pitch canker incidence and was greater in the fertilized versus the unfertilized plots. The authors concluded that the most aggressive raking regime in this case (annual raking) may eventually deplete site nutrition and reduce site productivity.

A pine straw removal study was initiated on the Savannah River Site in Aiken County, South Carolina in three 12-year-old longleaf pine stands (Fuquay; loamy Arenic Plinthic Kandiudults, Gunter; , and Troup; loamy Grossarenic Paleudults soils, McLeod and others 1979). McLeod and others (1979) summarized their findings as follows: (1) one year after removal of the “red” and “brown” pine straw a significant reduction in diameter growth was realized on the Fuquay and Troup soils but not the Gunter soil (Table 1), (2) removing the same two layers of needles in year two significantly reduced diameter growth on the Fuquay soil, with a slight (non-significant) diameter reduction on the Troup soil, and no diameter growth reduction on the Gunter soil, (3) three years of “red” and “brown” needle removal did not reduce diameter growth on the Fuquay or Gunter soil (Troup soil diameter growth findings were not reported), (4) significant reductions in needle N concentration on the Gunter soil (0.96 vs 0.77% N) and needle P concentration on the Fuquay (0.07 vs 0.05% P) and the Gunter (0.07 vs 0.05% P) were found in the rake versus no rake plots, and (5) a significant weight reduction (32%) in pine straw production on the Troup soil between the rake and no-rake plots (Table 1). There were no significant differences in pine straw nutrient concentrations between the rake and no-rake for K, Ca, and Mg during the study period. While the pine straw (litter layer) weights between the rake and no-rake plots were not statistically significantly different, the rake values at the end of the study period were 27% and 22% less than the unraked plots for the Fuquay and Gunter soils, respectively.

A study on the effects of pine straw removal (all layers vs only litter layer vs no removals) on xylem water potential and soil moisture content was initiated in an old-field 19-year-old longleaf stand (Ginter and others 1979) on the Savannah River Site in Aiken County, South Carolina. The soil was Troup (loamy Grossarenic Paleudults). Soil moisture and xylem water potential was measured for 7 weeks after litter layer (L) and litter+fermentation+humus (LFH) layers were removed. There were no pre-treatment soil moisture differences. They concluded the following: (1) two weeks following forest floor removal xylem pressure potential (XPP) in the control, litter layer and all layers removed plots diverged. (2) Trees in the LFH layers removed plots had the lowest xylem pressure potential (most stressed), trees in the L layer removed had intermediate XPP, and trees in the control plots had the highest XPP (least stressed, Table 1). (3) Differences in XPP were consistent throughout the season, regardless of rainfall patterns or drought. (4) Soil moisture was consistently lower in the L and LFH raked plots compared to the control at all three measured depths (0-12, 12-24, and 24-36 inches, table 1). (5) Trees in the L and LFH raked plots responded to rainfall but never recovered to the xylem pressure potential in the control plots beyond day 12. (6) If one considers 15 bars pressure to be the threshold point which photosynthesis is reduced then trees in the control, L, LFH plots had impaired photosynthesis for 6.2, 6.4 and 7.9 hours/day, respectively. This stress induced by litter removal treatments could contribute to the observed growth reduction due to this reduction in photosynthetic activity (McLeod and others 1979). Ginter and others (1979) concluded that litter layer or complete forest floor removal on low water holding capacity soils like the Troup may be more detrimental to tree growth than on soils with more intermediate to clay texture. Also, the more marginal the soil is fertility-wise the more the potential impact of intensive raking on stand growth.

Haywood and others (1995) installed a pine straw removal with and without 250 lbs/ac DAP fertilization and with summer or winter or no burning study in a 37-year-old longleaf stand in Rapides Parish, Louisiana. The soils were Ruston and Smithdale (fine loamy Typic Paleudults). They reported on the study three years after treatments were applied. They summarized the study as follows: (1) no real gain in pine straw production with 250 lbs/ac DAP one and two years after fertilization (may have been too early to be realized, and/or insufficient N in fertilizer, and/or K was needed), (2) significant increases in foliar P levels in the fertilized versus the unfertilized plots 3 years after treatment (YAT), (3) in the unfertilized plots only, the pine straw raked plots produced 1.7 ft2 basal area and 50 ft3 less volume per acre than the unraked plots 3 YAT (Table 1), (4) 250 lbs/ac DAP did not significantly increase longleaf pine diameter, height, or volume growth over the 3 year period (this may be due to low levels of K in the foliage and under fertilization with N), (5) they noted that extended summer droughts can cause premature needlefall. Normal peak needlefall occurred in late fall-early winter in this study but an extended summer drought in 1993 caused peak needlefall to occur 2 months early in September. Hennessey and others (1992) also noted that extended droughts can cause pine needles to fall 2 months earlier than normal.

Haywood and others (1998) continued the same study as reported by Haywood and others (1995) for another 3 years and found the following for 37- to 43-year-old longleaf: (1) two applications of 250 lbs/ac DAP increased 5 year wood volume in the raked plots by 1.5 cords/ac over the unraked controls, (2) the unraked, unfertilized and fertilized raked plots had a 0.80 inch greater dbh 5-year growth increment than the unfertilized, raked plots, (3) the unraked, unfertilized plots had 1.5 cords/ac greater volume than the raked unfertilized plots after five years (Table 1), (4) the two applications of 250 lbs/ac DAP increased pine straw by approximately 14 bales/ac/yr between 1991 and 1994 over the unfertilized, raked and unraked plots, (5) mechanical pine straw harvesting increased soil bulk density in the annual raked plots after three years (1.33 vs 1.44 gr/cm3) compared to the unraked plots, (6) soil bulk density did decrease after mechanical harvesting ceased to 1.32 gr/cm3, (7) available soil P was over 15 times greater (15.4 vs 0.81 ppm) in the DAP fertilized versus unfertilized plots two YAT, and (8) soil and foliar potassium (K) were considered to be deficient on all treatments.

Ross and others (1995) studied the effects of litter (L) layer versus complete forest floor (LFH) removal in loblolly and longleaf on the Savannah River Site in Aiken County, South Carolina with and without N+P fertilization and burning. The soil was Fuquay (loamy, Arenic Plinthic Kandiudults). Treatments were: (a) no treatment (control), (b) winter prescribe burn at three year intervals, (c) litter (L) layer raking in winter at three year intervals, and (d) total raking (LFH layers) in the winter on three year intervals (longleaf stand only). Ross and others (1995) summarized the following from the project after seven years: (1) there were no treatment effects on loblolly or longleaf basal area growth. (2) Litter mass and nutrient levels were approximately twice that of longleaf. (3) The humus mass and nutrient levels were were higher for the longleaf than the loblolly (longleaf stand was older). (4) Fertilization (100 N + 10 elemental-P) increased longleaf pine straw production by 100 to 175 bales/acre (Table 1) and weights of nutrients in the forest floor by 85% for N, 236% for P, 43% for Ca, and 57% for Mg. (5) Fertilization (100 N + 10 elemental-P) increased loblolly pine straw production by 54 to 73 bales/acre (Table 1) and nutrient weights by 43% for N, 179% for P, 109% for K, 25% for Ca, and 39% for Mg. (6) Raking decreased nutrient levels in the foliage of both species.

Table 1. Effects of pine straw raking on stand parameters

Reference species/
age(yrs)
State/
Soils
Treatments Stand Parameter/
Treatment
Effect on
Stand
Parameter
Lopez-Zamora and others 2001 slash
8 to 13-
yrs-old
Florida
Manderin
Hurricane
no rake, rake annual, every
2 or 4 yrs,
no fert, fert
diameter annual rake 0.20"
less than no rake
height growth reduced
with fertilization
raking N and P
in straw
removed up to 45
N and 4.5 P/ac
McLeod and others 1979 longleaf
12-yrs-old
S Carolina
Fuquay,
Gunter,
Troup
no rake, rake litter layer(L), rake all layers(T) diameter significant reduction in L and T rake plots on Troup and Fuquay soils
N and P
in straw
significant reductions
in N and P conc in
rake plots
pine straw weight 32% reduction in weight on rake vs
no rake plots on
Troup soil
Ginter and others 1979 longleaf
19-yrs-old
S Carolina
Troup
as McLeod
and others
1979
soil moisture
@ 0-12",
12-24",
24-36"
was consistently
lower in rake L and rake T plots than no rake @ all depths
xylem pressure potential (XPP) days 12 to 49 after raking trees in rake
L and rake T had
lower XPP
estimated hrs/day of impaired photosynthesis 6.2 hrs no rake

6.4 hrs rake L

7.9 hrs rake T
Haywood
and others (1995, 99)
longleaf
37 to 43- yrs old
Louisiana
Ruston
Smithdale
burn, no burn, fert, no fert, rake, no rake rake vs no rake and no fert 3 yrs after treatment raked plots grew 2 ft2 BA/ac and 50 ft3/ac vol. less than no rake
rake+fert (2x250 lbs/ac DAP) vs

rake+ no fert
rake+fert
increased volume
by 1.5cds over
rake+no fert
Ross and others 1995 longleaf
30's

loblolly
20-yrs-old
S Carolina
Fuquay
no burn, burn, no fert, fert (N), no burn/fert, no rake, rake on 3 yr intervals fertilization (100 lbs N/ac) vs no fert effect on pine straw production (PSP) fert increased
longleaf PSP by
100-175 bales/ac
and loblolly by
54-73 bales/ac
Dickens 1999 longleaf
9 and 32-yrs old
S Carolina
Alpin
no fert, fert (150N,65P, 125K), rake,
no rake
fertilization vs
no fert effect
on PSP, BA,
and vol/ac
fertilization vs no
fert increased pine straw production by 127 to 172 bales/ac, BA/ac by 25% and vol/ac by 0.5 to 1.5
cds over 4 yrs

Dickens (1999, 2001) found that NPK (150 N + 65 P + 125 K) fertilization increased longleaf pine straw production on deep sands (Alpin soil, Typic Quartzipsamments) by 127 and 172 bales/acre four years following fertilization compared to unfertilized controls in the 9- and 32-year-old stands (Figure 1 and 2). Merchantable volume was increased by 1.6 cords/acre in the fertilized compared to the unfertilized longleaf four years after treatment in the older thinned stand. Approximately 15% of the longleaf in the NPK fertilized plots of the unthinned younger stand became top-heavy, leaned over and never recovered. It is recommended that only 75 lbs N/acre with 50lbs elemental-P and K as needed for longleaf stands where mean dbh is less than 6 inches. Preliminary data from Dickens and others (2002 unpublished data) found that fertilization (NP, NPK, and NPKMgS) in a highly fertile 8-year-old slash pine (Tifton soil) stand increased pine straw production (first rake) over unfertilized plots by 11% to 33% sixteen months after application (Figure 3). Fertilization (NP, NPK, NPKMgS) increased pine straw production (Dickens and others 2002, unpublished data) in a thinned old-field slash pine stand (raked 3 times prior to thinning) by 39% to 76% twenty-three months after application (Figure 4) on more marginal soils (Wagram / Troup).

Jorgensen and Wells (1985) noted that decomposition and release rates of forest floor nutrients are highest in the first year after litterfall, with each element changing at it’s own rate. They estimated that 50% of P, 70% of K, 57% of Mg, and 10% of N are released from the organic form from their study of loblolly pine stands in North Carolina. After eight years of decomposition about 67% of organic matter, 60% of P, 90% of K, 67% of Ca, 79% of Mg and 27% of N are released from the organic form.

Summary of Effects of Raking on Stand Growth, Straw Production, and Water Stress with and without Fertilization

In general leaving the forest floor intact in pine stands has been shown to have the greatest soil moisture, tree xylem water potential, and maintains stand growth/health when compared to annual raking of the litter layer (uppermost recently fallen undecayed needles), or annual raking removing all the forest floor layers. Raking just the litter layer every three to four years appears to have the least adverse impact on tree growth. Pine growth decreased in all studies in plots where raking annually without fertilization were imposed. The more marginal the site from the standpoint of fertility and soil moisture status (deep sandy soils such as Lakeland, Kershaw, Alpin, Foxworth, and Troup; Typic Quartzipsamments and Grossarenic Udults) the larger the potential negative impact of annual raking on tree growth without fertilization. Highly fertile old-field sites on the lower and middle Coastal Plain lend themselves to pine straw harvesting. Fertilization did increase pine straw production in the majority of cases cited here. Fertilization, where pine straw was raked also increased wood volume production in all but two studies. One case N applied may not have been sufficient and K was not applied but was later deemed to be deficient (Haywood and others 1995, 1999). The other case was on an old-field (Lopez-Zamora 2001). Residual fertility may have sufficient to maintain the growth rate without additional fertilization and the applied N level (90 lbs/ac) may not have been sufficient for a significant response.

Fertilization Recommendations for Enhancing Pine Straw Production in Loblolly, Longleaf, and Slash Stands

Fertilization to enhance pine straw production can also enhance wood volume gain over a period of 4 to 8 years. Application timing, frequency of application, fertilizer forms and amounts can be critical based on stand and climatic factors. Urea (46-0-0) the most common form of N fertilizer used should be applied in the cool winter months to minimize N-volatilization losses. Ammonium nitrate (NH4NO3, 33-0-0) does not have the volatilization losses that urea has but N can be lost as nitrate leaching losses and can be substantial on coarse textured soils. Denitrification and N2 gas losses can occur with ammonium nitrate when applied to poorly drained soils that are anaerobic. Diammonium phosphate (DAP, 18-46-0) can be applied year around without major N loss concerns. The most common potassium (K) fertilizer form is muriate of potash (0-0-60). Typically, where needed 100 lbs of 0-0-60 is added to N plus P fertilizer prescriptions to obtain 50 lbs of elemental K. It is not common for pine stands to have calcium (Ca), magnesium (Mg), sulfur (S), manganese (Mn), boron (B), or copper (Cu) deficiencies. Jokela and others (1991) found that the addition of 24 lbs Mn/ac applied in a 7-year old slash pine stand on a poorly drained Ultic Haplaquods increased wood volume by 1/3 cd/ac/yr over the next 5 years on sites where foliar Mn was 20-80 ppm or less. Foliar analysis for these nutrients can determine whether there is a need for the addition of these nutrients.

If semi-annual, bi-annual, or annual raking is an objective then a five year fertilization schedule (Table 2) should enhance or maintain pine straw production in the near-term (2 to 5 years).

Table 2. Recommended fertilizer rates for a five year application regime

Species Age(yrs)/
Size(dbh)
N(lbs/ac) Elemental-P
(lbs/ac)
Elemental-
K3(lbs/ac)
Other Nutrients4
(lbs/ac)
loblolly1 8-30+ yrs 150-200 25 (Piedmont)
40-50 (Coastal Plain)
50-80 as needed based
on foliar analysis
longleaf < 6" dbh 75 25 (Piedmont)
40-50 (Coastal Plain)
50-80 as needed based
on foliar analysis
longleaf >= 6" dbh 75 25 (Piedmont)
40-50 (Coastal Plain)
50-80 as needed based
on foliar analysis
slash2 8-30+ yrs 150-200 40-50 (Coastal Plain) 50-80 as needed based
on foliar analysis
1,2 When in an unthinned stand N should be split applied over 2 to 3 years where fusiform canker incidence is greater than >30% in loblolly pine stands and > 25% in slash pine stands.
3 As needed based on foliar analysis. If < 0.35% for loblolly, <0.30% for longleaf, and less than 0.25 to 0.30% for slash then K is recommended.
4 As needed based on foliar analysis. If Ca is <0.12% for loblolly, <0.10% for longleaf and <0.08 to 0.12% for slash then Ca is recommended. If Mg is < 0.07% for loblolly, <0.06% for longleaf, and <0.04 to 0.06% for slash then add 25 lbs Mg/ac as K-mag or some other Mg form. If S is <0.12% for loblolly pine and < 0.10% for longleaf and slash then add 20-30 lbs S/ac. If foliar Cu and B are < 10 ppm then add B and Cu @ 1 lb B/ac or Cu @ 3 lbs/ac.

It is recommended where possible to retain the two lower layers of slightly to advanced decayed needles and other organic material to reduce evaporative losses. Fertilizer applications should be timed to minimize nutrient losses to raking displacement, leaching, denitrification, or volatilization. Raking timing may have to be modified (commonly done in late winter to mid-spring) to accommodate winter urea application. Erosion potential should be considered. Raking is not recommended where slope is greater than 8%. Raking frequency should be based on inherent soil water holding capacity, cation exchange capacity, percent organic matter, and fertility site factors. Droughty, infertile soils with low CEC and organic matter may be scheduled for raking only the litter layer on three to four year cycles to maintain acceptable tree growth rates. Fertilization can aid in enhancing tree growth and pine straw production on these marginal soils (Dickens 1999, 2001) when raking occurs in 3 to 4 year cycles.

The use of diagnostic tools such as: leaf area index (LAI) done in mid-summer at LAI peak, soil sampling (for soil test P, based on procedure if < 4-6 ppm or 8-12 lb/ac then P is deficient), foliar sampling (done in winter months, 10-20 dominant trees/stand, upper 1/3 crown, south side, first flush of previous year’s growth), and knowledge of soils can be valuable in fertilizer prescriptions. These diagnostic tools can be very valuable when several stands are to be raked and fertilized and ranking or prioritorizing stands to be fertilized would be cost-beneficial. Knowledge of foliar nutrient status, soil test P, soils, and LAI prior to stand fertilization can serve as a baseline for (1) comparing changes (magnitude) in foliar nutrient status, soil P levels, and LAI after fertilization, and (2) when re-fertilization should occur (duration) and with what nutrients. Post fertilization LAI , foliar, and soil sampling should be done prior to the next planned fertilizer application (2 to 4 years after first application) to tailor the prescription to stand needs. Commonly stands are fertilized initially with N+P. Subsequent fertilizer applications may entail the addition of K, Ca, S, Mg, or micro-nutrients as these nutrients become site depleted. Foliar analysis can indicate stand needs of K, Ca, Mg, S, Mn, B, and Cu.

Good competition control is essential to keep raked stands clean, to optimize percent of stand to be raked, and to enhance attractiveness to contractors. Good competition control can also have stand growth benefits. Fortson and others (1996) and Oppenheimer and others (1989) noted that complete weed control in age 9 to 15-year-old loblolly and slash pine stands increased wood volume production by ½ and 1/3 cord/ac/yr for 8 to 14 years in unraked stands, respectively.

Annual, bi-annual, or every third to forth year fertilization regimes are options that may fit better into a stand where pine straw is raked. In many cases raking and fertilizer application timing may reduce the attractiveness of annual or bi-annual fertilization. The dosage of N, P, and K in Table 2 can be modified to estimate N, P, and K application levels. Annual N,P,K dosage may be 50 to 75 lbs N/ac, 15 to 20 lbs elemental-P/ac, and 20 to 25 lbs K/ac. Foliar analysis will help in subsequent nutrient prescriptions. Fertilization in intervals greater than five years will help with wood volume gain (volume gain peaks after 4-5 years but continues into 8 years for loblolly pine with 200N+25 or 50P, NCSUFNC 1998) but may not maintain pine straw production levels. Generally pine straw response to fertilization lasts 4 to 5 years (Dickens 1999).

Nitrogen fertilization in stands with a high (> 25% for slash and >30% for loblolly) of stem fusiform cankers in loblolly and slash pine stands should be split applied over 2 to 3 years to minimize stem breakage. Overloading heavily stem cankered stands with the large single dose (150 to 200 lbs/ac) of N greatly increases crown volume and weight and some stems can not handle the sudden weight gain.

Literature Cited

Dickens, E.D. 1999. Effect of inorganic and organic fertilization on longleaf pine tree growth and pine
     straw production. In: Proceedings of the 10th Biennial So. Silvi. Res. Conf., Shreveport, LA. Feb.
     16-18, 1999. pp. 464-468.

Dickens, E.D. 2001. Fertilization options for longleaf pine stands on marginal soils with economic
     implications. In: Proceedings of the 31st Annual Southern Forest Economics Workshop. March 27-
     28, 2001. Atlanta, GA. pp. 67-72.

Doherty, B.A., R.J. Teasley, J.C. McKissick, and B. Givan. 2000. Nineteen ninety-nine farmgate value
     report. UGA CAES Center for Agribusiness and Econ. Development, Center Staff Report No. 6.
     Athens, GA 160 p.

Fortson, J.C., B.D. Shiver, and Shackleford, L. 1996. Removal of competing vegetation from established
     loblolly pine plantations increases growth on Piedmont and Upper Coastal Plain sites.
     SJAF 20:188-192.

Ginter, D.L., K. W. McLeod, and C. Sherrod, Jr. 1979. Water stress in longleaf pine induced by litter
     removal. Forest Ecology and Mgmt. 2: 13-20.

Haywood, J.D., A.E. Tiarks, M.L. Elliott-Smith, H.R. Pearson. 1995. Management of longleaf stands for
     pine straw harvesting and the subsequent influence on forest productivity. In: Proceedings of the 8th
     Biennial So. Silvi. Res. Conf., Auburn, AL, Nov. 1-3, 1994

Haywood, J.D., A.E. Tiarks, M.L. Elliott-Smith, H.R. Pearson. 1998. Response of direct seeded Pinus
     palustris
and herbaceous vegetation to fertilization, burning, and pine straw harvesting. Forest
     Ecology and Mgmt. 14, No. 2.: 157-167.

Hennessey, T.C., P.M. Doughtery, P.M. Cregg, and B.M. Wittwer. 1992. Annual variation in needle fall
     of a loblolly pine stand in relation to climate and stand density. Forest Ecology and Mgmt. 51: 329-
     338.

Jokela, E.J., W.W. McFee, and E.L. Stone. 1991. Micronutrient deficiency in slash pine: response and
     persistence to added manganese. Soil Sci. Soc. Am. J.: 55:492-496.

Jorgensen, J.R. and C.G. Wells. 1985. Forester’s primer on nutrient cycling - a loblolly pine
     management guide. USDA Forest Service GTR SE-37. Asheville, NC. 42 p.

Lopez-Zamora, I., M.L. Duryea, C. McCormack-Wild, N.B. Comerford, and D.G. Neary. 2001. Forest
     Ecology and Mgmt. 148: 125-134.

Morris, L.A., E.J. Jokela, and J.B. O’Conner, Jr. 1992. Silvicultural guidelines for pinestraw
     management in the SE US. GA Forest Research Paper No. 88. Atlanta, GA: GFC. 11 p.

McLeod, KW., C. Sherrod, Jr., and T.E. Porch. 1979. Response on longleaf pine plantations to litter
     removal. Forest Ecology and Mgmt. 2:1-12.

North Carolina State University Forest Nutrition Coop. 1998. Twenty-eighth annual report. NCSU,
     Raleigh, NC 28 p.

Oppenheimer, M.J., Shiver, B.D., and J.W. Rheney. 1989. Ten-year response of mid-rotation slash pine
     plantations to control of competing vegetation. Can. Journal of Forest Res. 19: 329-334.

Ross, S.M., W.H. McKee, Jr., and M. Mims. 1995. Loblolly and longleaf pine responses to litter raking,
     prescribe burning, and nitrogen fertilization. In: Proceedings of the 8th Biennial So. Silvi.
     Res. Conf., Auburn, AL, Nov. 1-3, 1994. pp. 220-224.

Figure 1. Fertilization effect on pine straw production in a 1986 planted longleaf stand (Alpin soil) in Chesterfield County, SC. Treatments applied may 1995. NPK as 10-10-10 @ 1500 lbs/ac. Lime stabilized biosolids @ 3.2 dry tons/ac.
Figure 1. Fertilization effect on pine straw production in a 1986 planted longleaf
stand (Alpin soil) in Chesterfield County, SC. Treatments applied may 1995.
NPK as 10-10-10 @ 1500 lbs/ac. Lime stabilized biosolids @ 3.2 dry tons/ac.

Figure 2. Fertilization effect on pine straw production in a thinned twice 1963 planted longleaf stand (Alpin soil) in Chesterfield County, SC. Treatments applied may 1995. NPK as 10-10-10 @ 1500 lbs/ac. Lime stabilized biosolids @ 3.2 dry tons/ac.
Figure 2. Fertilization effect on pine straw production in a thinned twice 1963 planted
longleaf stand (Alpin soil) in Chesterfield County, SC. Treatments applied may 1995.
NPK as 10-10-10 @ 1500 lbs/ac. Lime stabilized biosolids @ 3.2 dry tons/ac.

Figure 3. Effect of fertilization in an old-field slash pine stand (Tifton soil) on first rake bale/ acre production. Treatments applied February 2001. Litter layer samples taken June 2002.
Figure 3. Effect of fertilization in an old-field slash pine stand (Tifton soil) on first rake bale/
acre production. Treatments applied February 2001. Litter layer samples taken June 2002.

Figure 4. Effect of fertilization in a thinned old-field slash pine stand (Wagram and Troup soils) on bale/acre production. Treatments applied March 2000. Litter layer samples taken February 2002. Stand was raked three times prior to thinning.
Figure 4. Effect of fertilization in a thinned old-field slash pine stand (Wagram and Troup
soils) on bale/acre production. Treatments applied March 2000. Litter layer samples taken
February 2002. Stand was raked three times prior to thinning.

line

The Bugwood Network and Forestry Images Image Archive and Database Systems
The University of Georgia - Warnell School of Forestry and Natural Resources and College of Agricultural and Environmental Sciences - Dept. of Entomology

Last updated December 2018

Home | Image Usage | Accessibility Policy | Privacy Policy | Disclaimers | Contact Us | Help