Shade created by the trees greatly modifies the microclimate of the alleys between tree rows and affects the quantity and quality of forage produced there. Selection of grasses that are adapted to silvopasture is therefore essential. The objectives of this study were to evaluate dry matter (DM) yield and crude protein (CP) of bermudagrass [Cynodon dactylan (L.) Pers.] and bahiagrass (Paspalum notatum Flugge) cultivars in a 20-yr-old loblolly pine (Pinus taeda L.) plantation thinned to a spacing of 1.2 m x 12 m compared with grasses in open (no trees) pasture. Four grasses were studied in each area: 'NuMex-Sahara' and 'Ranchero Frio' bermudagrasses and 'Tifton 9' and 'Pensacola' bahiagrasses. There were significant differences among grasses within shaded and unshaded areas (range 310-2880 kg ha(-1)). Tifton 9 had the highest DM yield in the shaded and unshaded areas. Crude protein concentrations of all cultivars were significantly higher in the shaded than in unshaded areas (range 90-181 g kg(-1)). Ranchero Frio had significantly higher CP concentration than the other cultivars in the shaded area, but Numex-Sahara had significantly higher CP in the unshaded area. Overall, high CP and DM yield could be maintained in a silvopastoral system of loblolly pine: forage grasses by identifying and selecting appropriate cultivars.
There is little of information on cattle productivity in silvopasture in the Southeast USA. Utilizing 12-yr-old slash pines (Pinus elliotti Engelm. var. densa Little &Dorman) planted in 1.2 X 2.4-m double-rows spaced 12.2 m apart, forage and cattle production in two silvopastures with 309 and 494 trees ha(-1), respectively, were compared with open pasture (no pines). All pastures were 'Pensacola' bahiagrass (Paspalum notatum Flugge) with legumes, 'Florida' carpon desmodium [Desmodium heterocarpon (L.) DC.) and 'Shaw' vigna (Vigna parkeri Bak.) and were stocked at 2.5 cow-calf pairs ha(-1). Braford cows (avg. 511 kg) and calves (initial 112-d-old, 164 kg) grazed the two silvopastures and open pasture for 107 d from 1 June to 15 Sept. 2003 (weaning). Total forage accumulation for the period was greater in open pasture (10180 kg ha(-1)) than in the two silvopastures which were not different (avg. 7490 kg ha(-1)). Forage mass averaged 2190 kg ha(-1) in all pastures at the start of grazing and declined linearly over the grazing period in silvopastures. Forage mass changed in open pasture by increasing until 21 July, then declining to 15 September. Cows lost more weight on the silvopastures (-88 kg) than in open pasture (-22 kg). Calf weight at weaning was higher on open pasture (212 kg) than on silvopastures (179 kg). Pines reduced forage accumulation by 27% and calf weight by 16% compared with open pasture. Profitability of silvopasture will depend on whether loss of income from livestock later in the timber rotation will be offset by the increasing value of timber or other sources of forest-related income.
Greater crop yields and quality can be obtained if environmental conditions are favorable during plant development. The objective of the study, conducted at Quincy, FL from 1995 through 1997, was to evaluate the influence of air temperature and precipitation on growth, development, and yield of 'DP 5409' cotton (Gossypium hirsutum L.). Plant development was divided into four phases: planting to emergence, emergence to pinhead square, pinhead square to blooming, and blooming to boll opening. Highest lint yields of cotton could be expected with air temperatures of 26.0 and 25. 1 degrees C from emergence to pinhead square and blooming to boll opening phases, respectively. Precipitation had a positive influence on cotton lint yields. We would expect an increase in cotton yields of 13, 38, 46, and 7 kg ha(-1) with 1-mm precipitation increase from planting to emergence, emergence to pinhead square, pinhead square to blooming, and blooming to boll opening, respectively. Generally, there is a whole suite of opportunities and limitations for plant growth, but air temperature and precipitation explains some changes in development of cotton under field conditions.
Goats require protein supplementation while grazing bahiagrass (Paspalum notatum Flugge) during summer in Florida. We measured weight gains of Boer x Spanish goats (6-7 mo old) in July-November, 2003 (140 d) while grazing leucaena [Leucaena leucocephala (Lam.) de Wit] with bahiagrass (LEUC), compared with grazing bahiagrass alone (CON), or bahiagrass with soybean (Glycine max L.) meal fed at 50% of daily protein requirement (SBM). All goats received one-third of their daily energy requirement. Goats were continuously stocked on SBM and CON at 22 goats ha(-1). Goats on LEUC were inoculated with mimosine-detoxifying microbes (Synergistes jonesii), were stocked at 11 goats ha(-1), and were rotated every 28 d between two paddocks. Average daily gains were positive on LEUC in each of the five, 28-d weigh periods, but nil or negative in SBM and CON on two occasions in October and November. Over 140 d of grazing, goats on LEUC grew faster (P = 0.0016) at 59 g d(-1) and gained 8.3 kg head(-1) than those on SBM and CON with 31 and 23 g d(-1), and 4.3 and 3.3 kg head(-1), respectively. Total liveweight gains per unit of land were similar (P = 0.2532) among the treatments, and averaged 94, 97, and 74 kg ha(-1) for LEUC, SBM, and CON, respectively. Leucaena results in greater individual weight gains for meat goats grazing bahiagrass in the summer than feeding a supplement that provides 50% of daily protein requirement.
Silicon (Si) fertilization for rice (Oryza sativa L.) and sugarcane (Saccharum officinarum L.) production on organic and sandy soils m, south Florida has become routine. It has given rise to an interest among growers in finding suitable Si fertilizers in addition to the currently used sources of calcium silicate (CaSiO3). A laboratory procedure has been developed for identifying candidate Si fertilizers (potential Si sources) based on Si dissolution in tris hydroxymethyl aminomethane (TRIS) buffered water (pH = 7) over a 48-h period. It was found that there is good correlation between mineral Si sources with adequate amounts of CaSiO3 and Si uptake in rice straw. Similar Si sources also demonstrate a classic first order leaching reaction. Therefore, the lab procedure can identify suitable Si sources for further testing after the second leaching day due to its first order predictability.
Bahiagrass (Paspalum notatum Flugge) is grown on 75% of Florida's improved pastures and a major pasture grass in southeastern U.S.A. However, since there is a need to find better cultivars, six bahiagrass entries consisting of cultivars 'Argentine', 'Pensacola', and 'Tifton 9' as standards were compared with experimental lines of bahiagrass developed at Tifton, GA; 'Tifton 7' (a tetraploid bahiagrass), and two recurrent restricted phenotypic selection (RRPS) populations 'RRPS Cycle 18' and 'RRPS Cycle 23' over 3 yr. The randomized complete block experiment was harvested from April to December each year on 30-d intervals, to a 7-cm stubble, and dry biomass (DB) yield, crude protein (CP), in vitro organic matter digestion (IVOMD) were determined. There was no difference between Tifton 7, Tifton 9, Cycle 18, Cycle 23, and Argentine in annual DB yield (11.6 Mg ha(-1)). However, Tifton 7 and Tifton 9 (12.0 Mg ha(-1)) were higher than Pensacola (10.3 Mg ha(-1)). Differences in forage CP concentration and IVOMD were not consistent among bahiagrass entries from year to year, regardless of harvest period. However, forage CP and rVOMD concentrations were generally highest in April (157 and 534 g kg(-1)), October (157 and 542 g kg(-1)), and December (177 and 587 g kg(-1)), respectively. Crude protein and rVOMD concentrations in the June (113 and 467 g kg(-1)) and August (122 and 482 g kg(-1)) were always the lowest, respectively. The results of this study may be useful in assisting plant breeders and growers to make better choices when selecting bahiagrass cultivars for pasture renovation.
Crop rotation affects populations of phytoparasitic nematodes. Our objective was to find a multiple-cropping history that resulted in low nematode population densities. Three triple-cropping histories were investigated over 2 yr: 1) Fall-planted sweet corn (Zea mays L.), winter crop of Austrian winter pea (Pisum arvense L.), sweet corn in 2002/2003, and the sequence was repeated in 2003/2004; 2) Fallplanted cowpea (Vigna unguiculata [L.] Walp.), winter crop of Austrian winter pea, sweet corn, with the sequence repeated in 2003/2004 except that lima bean (Phaseolus lunatus L.) was the fall crop; 3) Fall- planted sunn hemp (Crotalariajuncea L.), Austrian winter pea, sweet corn, and the sequence was repeated in 2003/2004. Histories were whole-plot treatments in a completely-randomized design, and N sources [(lupine (Lupinus angustifolius L.) hay, vetch (Vicia villosa [L] Roth) hay, and ammonium nitrate)] were sub-plot treatments. Nematodes were counted before and after sweet corn and Austrian winter pea crops. History I had the highest buildup of nematodes at the start of the study and ranged from a ratio of 12:1 greater for stubby root [Paratrichodorus minor (Colbran) Siddiqi] to 62:1 for root-knot (Meloidogyne spp.). Lesion (Pratylenchus spp.) and ring (Criconemella spp.) populations remained extremely low in all histories over 2 yr, except for in History 1, demonstrating the ability of sweet corn to increase these nematodes. Sunn hemp and Austrian winter pea were found to decrease root-knot nematodes, while sweet corn was found to increase their numbers. Sunn hemp and Austrian winter pea are warm and cool season crops, respectively, that could be used back-to-back for two seasons of nematode suppression.
The benefits of using perennial peanut (Arachis glabrata Benth.) groundcover in citrus (Citrus spp.) groves of central Florida may be compromised by the presence of common weed species with potential host-status for nematode pests. Sixteen plots with varying perennial peanut ground cover were delimited within a young citrus grove. Nematode communities within these plots were related to plant species composition. Results with plant-parasitic genera were most consistent, showing positive associations with bahiagrass (Paspalum notatum Flugge), the most common weed species present, and negative associations with perennial peanut. Near the end of the growing season (October-December), numbers of Belonolaimus and Hoplolamius were highly correlated (P < 0.05) with bahiagrass ground cover (r = 0.597 to 0.808). Both of these nematodes were negatively correlated (P < 0.10) with perennial peanut ground cover (r = -0.574 to r = -0.685). These results illustrate the importance of maintaining weed-free ground cover in managing plant-parasitic nematodes in a citrus grove.
Leucaena (Leucaena spp. Benth.) is a forage tree legume that can provide nutritious forage for grazing ruminants, but acid soils often require liming. Use of soluble liming materials may be more practical than deep liming for ameliorating subsoil acidity. In two glasshouse studies, we determined the effects on leucaena growth and soil properties of deep-profile application of dolomite, and mixtures of dolomite and gypsum vs. surface-applied dolomite. In the first study, applications of 8 Mg ha(-1) dolomite to A (A8D), both A and E (AE8D), and A, E, and Bh horizons (AEBh8D) were compared with an untreated control in a completely randomized design (CRD) with four replications. Dolomite increased pH, and concentrations of P, Ca, and Mg in the soil, but K and Al were not affected. The AE8D and AEBh8D treatments gave greatest shoot height, taproot length, and shoot, root and nodule dry weights. In the second study, treatments included A8D, AE8D, and AEBh8D; and incorporation of 2 Mg gypsum ha(-1) alone; and 1, 2, 3, or 4 Mg gypsum ha(-1) + 8 Mg dolomite ha(-1) mixtures in the A horizon in CRD. Similar results were obtained as in Experiment I, but application of gypsum-dolomite mixtures to the A horizon was not better than dolomite alone. Thus, leucaena growth could be improved more with subsoil incorporation of dolomite than with application to the A horizon only.
Characterization of groundwater quality allows evaluation of groundwater pollution and provides information for better management of groundwater resources. This study demonstrated how to apply principal component analysis (PCA) and principal factor analysis (PFA) techniques to characterize groundwater quality. Data for 21 parameters collected from 36 shallow groundwater wells in the lower St. Johns River basin, Florida during 2003 to 2004 were used for analysis. The PCA technique was employed to evaluate correlations among groundwater quality, parameters, while the PEA technique was used to determine parameters that are most important in assessing groundwater quality changes. Results show that seven groundwater parameters, namely Mg, Na, SO4, total dissolved solids (TDS), Cl, total phosphorus (TP), and PO4 were most important in explaining variations of groundwater quality. In general, F, Fe, turbidity, and groundwater temperature were uncorrelated Kith each other or with other parameters selected in this study, whereas Ca, Cl, Mg, Na, K, and TDS were correlated with each other. For the nutrient-related parameters, total Kjeldahl nitrogen (TKN) was correlated with NH4 but not with nitrate and nitrite, while TP was correlated with PO4, NH4, and TKN. PCA and PFA techniques are useful tools for characterizations of groundwater quality.
Measuring the quantity of silica (SiO3-2) in sugarcane (Saccharum officinarum L.) leaves is necessary since its presence is important to the health of the plant. Silica is presently determined by wet chemistry that is time consuming (2 to 4 d) due to several processing steps. Compared to the wet chemistry method, silica concentration can be obtained in I to 2 d by measuring the electrical capacitance of dried sugarcane leaves. Preliminary studies showed that a correlation (r = 0.99) exists between inverse capacitance (pF(-1)) and silica concentration. Data between capacitance measurements of blind samples with known silica concentrations and from previous wet chemistry analysis were in excellent agreement, (r = 0.92-0.98). Use of electrical capacitance for determining silica concentration does not require plant digestion and is environmentally sound since chemical disposal is not necessary.
Peat soils in the Everglades Agricultural area of south Florida are subsiding and releasing nutrients in waterways due to decomposition by aerobic microorganisms. Restoring peat soil in the Everglades involves adding organic matter back to the soil as did the native sawgrass (Cladium jamaicense Crantz) in predrainage time and removing nutrients from soil water. It is not certain if sawgrass is more efficient at accumulating dry matter (DM) than agricultural crops. This experiment was conducted to compare DM yield distributions and root morphology of sugarcane (Saccharum spp.), sawgrass, and St. Augustinegrass [Stenotaphrum secundatum (Walt.) Kuntze] growing under different water-table depths. Plants were grown outside in 38-L pots containing a Pahokee muck soil (Euic, hyperthermic Lithic Haplosaprist) under 15- and 30-cm water tables. All plants were harvested after 11 mo. Across water-table treatments, sugarcane produced 55 kg m(-2) total DM (above plus below ground), while sawgrass and St. Augustinegrass had similar total DM yields averaging 5 kg m(-1). Sawgrass allocated 34% of its DM below ground averaged across water-table depths compared with 14 and 8% for sugarcane and St. Augustinegrass, respectively. However, sugarcane had 4 and 20 times more below ground DM than sawgrass and St. Augustinegrass, respectively. Sugarcane had 308 km m(-3) of total root length averaged across water-table treatments compared with an average of 24 km m(-1) for sawgrass and St. Augustinegrass, indicating that sugarcane had a much greater potential for absorbing nutrients. Sugarcane appears to have potential for building peat soil in the Everglades while reducing nutrient loading in ground water and allowing for coexistence of agriculture in soil restoration efforts.
Loss of P from agricultural land threatens water quality in south Florida. A study was conducted to examine the feasibility of using natural zeolite to decrease P leaching loss under field conditions. The effects of zeolite addition (0 and 5000 kg ha(-1)) at three P rates (0, 50, 100 kg ha(-1)) on P concentrations in leachate and soil were investigated in sweet corn (Zea mays L. var. rugosa) at Homestead, FL, on a Krome very gravelly loam (loamy-skeletal, carbonatic, hyperthermic Lithic Udorthents). Total P (TP) of leachate averaged 1.1 mg P L-1, and the proportion of orthophosphate (OP) increased with increasing leachate volume. Mean soil TP concentration in zeolite-amended plots was 3314 mg P kg(-3) soil, and mean soil AB-DTPA extractable P was 125 mg P kg(-1) at 100 kg P ha(-1). Main effects of P rates and zeolite addition were not significant on leachate OP and TP, but a significant interaction was found on TP at one sampling event where leachate TP concentrations with zeolite addition were 58% higher than those at 0 kg P ha(-1) but 27% lower at 100 kg P ha(-1). Soil TP concentration in zeolite-amended plots was less than that in the control. Increasing P rate increased extractable P but not TP in soil. There was no interaction effect on either soil extractable P or TP. In opposition to our hypothesis, zeolite addition appeared to increase P leaching loss by decreasing soil TP.
Lisianthus [Eustoma grandiflorum (Raf.) Shinn.] is a cut flower that is increasing in importance to the floriculture industry in Florida. Although lisianthus was observed to be susceptible to root-knot nematodes (Meloidogyne spp.), many commercial cultivars; have not been tested. Two greenhouse trials were conducted to examine the resistance and tolerance of eight lisianthus cultivars against M. incognita (Kofoid & White) Chitwood race 1. Snapdragon (Antirrhinum majus L.) was included in these trials as a root-knot susceptible cut flower control, whereas two larkspur [Consolida ajacis (L.) Schur.] cultivars were included for additional information. Highest nematode reproduction in snapdragons in both trials confirmed the viability of the nematode inoculum. Lisianthus cultivars tested in these trials ('Balboa Purple', 'Balboa White', 'Catalina White', 'Echo Blue', 'Malibu Blue Blush', 'Ventura Blue Rim', 'Ventura Purple', and 'Laguna Pink Rim') are resistant to M. incognita race 1, and their shoot weight was not affected by the nematode. Larkspur cultivars ('Qis White' and 'Qis Dark Spur') were relatively poor hosts to root-knot nematodes, but shoot weight of Qis White was reduced by the nematode. Shoot weight was a better indicator of nematode tolerance than plant height. These results identify nematode-resistant cultivars that could enable cut-flower growers to manage nematode pests through crop rotation.
Landfill liners are designed to minimize the migration of leachate to the surrounding soil and groundwater. Conventional final covers of landfills are designed to minimize percolation of rainwater into the waste and are constructed with layers having low saturated hydraulic conductivity. Alternative cover designs are sometimes allowed by regulations, such as evapotranspiration (ET) covers, which exploit the water storage capacity of soils and the water removal capability of vegetation. Two tests sections simulating final covers for landfills were constructed to evaluate their field performance. Each test section consisted of a lysimeter pan to collect percolation from the base of the cover, a collection system of surface run-off, and sensors to monitor the hydrologic variables. One test section was an ET cover consisting of a 1300-mm thick monolithic layer of native clayey soils mixed with organic amendments and vegetated with hybrid poplar (Populus sp.) trees and an understory of bermudagrass [Cynodon dactylon (L.) Pers.] The other test section was a conventional cover consisting of a 450-mm thick barrier layer of compacted clay overlain by an erosion protection layer 150-mm thick.Percolation from the conventional test section was 1.7 times greater than the ET test section. Percolation represented 14% (401 mm) of the applied water for the ET cover and 27% (698 mm) for the conventional cover, even though more water was applied to the ET cover to establish the trees. Simulated percolation agreed closely with observed results. Simulated water contents, however, were higher than measured water contents.
The organic soils (Histosols) of the Everglades Agricultural Area (EAA) formed when organic matter (OM) production exceeded OM decomposition because of flooded conditions that limited soil oxygen. Following drainage of the EAA, OM decomposition has exceeded production, resulting in loss of soil and a lowering of the surface elevations (subsidence). Predictions made in 1951 of the demise of agriculture in the EAA by 2000 did not materialize because growers found ways of adapting to decreasing soil depths, and sugarcane (Saccharum spp.), which is fairly water tolerant, became the principle crop. What about the next 50 yr? It is projected that in 2050 nearly half of the EAA will have soils < 8 inches (20 cm) in depth, primarily south of the Bolles canal. Sugarcane production will be difficult and costly on the more shallow soils, but not impossible. These areas should be suitable for pasture, but not for most vegetables. Water control will be crucial, since soil storage will be minimal. More of the EAA could be suitable for agriculture with implementation of soil-conserving practices. Future agricultural production in the EAA may depend more on commodity prices and governmental policies than on soil depths. Urban planners predict minimal population increases in the EAA, but relatively low land prices may be attractive to developers. Particularly on severely subsided soils, landowners may explore biomass production, aquaculture, hunting reserves, water storage, and mining as alternatives to traditional agriculture.
Valdosta State University owns property that includes a borrow pit excavated in 1961 to supply sand as fill during construction of Interstate Highway 75. This pit has revegetated naturally with no remediation, allowing investigation of natural rates of C sequestration in the pit over the last similar to 40 yr. Three distinct areas have been identified in the pit based on vegetation: an area of mixed deciduous and pine (Pinus spp.) trees in the deepest part of the pit, a sparsely vegetated area on the edge of a terrace within the pit, and an area with grass and mixed deciduous and pine trees. Soils (Valdosta series, Siliceous, thermic Psammentic Paleudults) outside the pit were also sampled as a control. Total soil C was measured and bulk density (BD) was determined. Mass of soil C in the upper meter of the profile was determined (total soil C * BD). Total profile soil C values averaged 2.2 kg C m(-2) in the deep pit, 0.4 kg C m(-2) in the sparsely vegetated area, 3.6 kg C m(-2) in the grassy area, and 5.9 kg C m(-2) in the control. Piezometers indicated water was often close to or above the surface in the deep pit and grassy areas and > 2-m deep in the sparsely vegetated area. Carbon sequestration rates are controlled by vegetative type and density which, in turn, appear to be controlled by soil bulk density, availability of soil water, and probably soil nutrient content (not measured).
Nineteen cultivars of caladium. (Caladium X hortulanum Birdsey) were evaluated in a greenhouse for resistance and tolerance to the root-knot nematode (Meloidogyne incognita [Kofoid & White] Chitwood). Caladium corms were planted in a sand:peat (4: 1) mix in pots and either inoculated or not inoculated with similar to 1000 hatched juveniles of M. incognita. Each of the cultivar x inoculation combinations was replicated six times. Plants were grown for 5 mo and evaluated for plant growth and final nematode populations. The cultivars 'Candidum,' 'Candidurn Junior,' 'Fannie Munson,' 'Frieda Hemple,' 'Pink Gem,' 'Pink Symphony,' 'Pink Beauty,' 'Postman Joyner,' 'Rosebud, and 'White Christmas' were relatively resistant to root-knot nematodes. Cultivars 'Gingerland,' 'Kathleen,' 'Miss Muffet,' 'Mrs. W. B. Sanders,' 'Pink Glow,' 'Red Frill,' 'Triumph de la Exposition,' 'White Queen,' and 'White Wing' were susceptible to root-knot nematodes and supported higher numbers of nematodes (> 300 root system(-1)) than the other cultivars, which supported very few nematodes (< 35 root system(-1)). Leaf number, shoot number, number of large leaves, shoot and root weight of all cultivars were rarely affected by M. incognita inoculation. Results indicated that caladium cultivars tested were tolerant to M. incognita infection under greenhouse conditions and some cultivars were relatively resistant to M. incognita as well.
The effectiveness of chemical amendments in reducing P losses from manure impacted Florida soil was evaluated using a variety of protocols, including total elemental analysis, short-term laboratory equilibrations, column leaching experiments, and simulated rainfall studies. Amendments used included: two Fe-humates [a Fe-water treatment residual (WTR) and a titanium-mine waste], two Al-WTRs, one Ca-WTR, a coal combustion slag, a Si-rich material (Pro-Sil), a Leonardite material (dinoSoil), and two agricultural materials (lime and gypsum). In equilibration studies, Al-WTRs were the most effective at sorbing P, while Fe-humate sorbed the least P of all treatments. Other amendments effectively reduced soluble P, but increased suspension pH and electrical conductivity (EC) to an extent expected to adversely affect plant growth. Gypsum was the most effective amendment in reducing P leaching in small column studies. DinoSoil treatment significantly altered the soil hydraulic properties, yielding the greatest runoff volumes in a simulated rainfall study. Total P loss (runoff + leachate) was largely determined by the leaching component, and was essentially all soluble reactive phosphorus (SRP) for both bare and grassed soil surfaces. AD treatments reduced runoff SRP compared to the control. Amendment effects in the grassed rainfall study (dominated by leaching) were inconsistent with results from the small column leaching study, possibly due to the different hydraulic conditions and kinetic factors involved in the two studies. The Al-WTRs amendments were recommended for field evaluation.
Plant roots are reported to enhance the aeration of soil by creating secondary macropores which improve the diffusion of oxygen into soil as well as the supply of methane to bacteria. Therefore, methane oxidation can be improved considerably by the soil structuring processes of vegetation, along with the increase of organic biomass in the soil associated with plant roots. This study consisted of using a numerical model that combines flow of water and heat with gas transport and oxidation in soils, to simulate methane emission and oxidation through simulated vegetated and non-vegetated landfill covers under different climatic conditions. Different simulations were performed using different methane loading flux (5-200 g m(-2) d(-1)) as the bottom boundary. The lowest modeled surface emissions were always obtained with vegetated soil covers for all simulated climates. The largest differences in simulated surface emissions between the vegetated and non-vegetated scenarios occur during the growing season. Higher average yearly percent oxidation was obtained in simulations with vegetated soil covers as compared to non-vegetated scenario. The modeled effects of vegetation on methane surface emissions and percent oxidation were attributed to two separate mechanisms: (1) increase in methane oxidation associated with the change of the physical properties of the upper vegetative layer and (2) increase in organic matter associated with vegetated soil layers. Finally, correlations between percent oxidation and methane loading into simulated vegetated and non-vegetated covers were proposed to allow decision makers to compare vegetated versus non-vegetated soil landfill covers. These results were obtained using a modeling study with several simplifying assumptions that do not capture the complexities of vegetated soils under field conditions.
