Hardwood Sawdust Research Articles

Active removal of biochar by earthworms (Lumbricus terrestris)

Abstract The role earthworms play in the cycling of biochar in the soil column is poorly understood. While some studies show that earthworms favor a biochar-rich environment, they are ambiguous as to whether earthworms actively remove it and/or possibly consume it, or whether biochar indirectly provides a more favorable habitat. More importantly, associating the properties of different biochars to habitat preference by earthworms has received almost no attention. Courts were established with eight biochars from different feedstocks with varying in physicochemical properties. Circular piles (1.5 g) of biochar were applied to the surface of mesocosms containing field soil and 25 earthworms. Removal was quantified by digitally photographing the biochar samples and visually estimating disappearance over time. Most biochars were actively removed by the earthworms. The most preferred biochar was an aged biochar (>70 years) harvested from charcoal mounds, whereas the least preferred was a fast-pyrolysis biochar made from hardwood sawdust. There was an inverse relationship between the removal of biochar by earthworms and total carbon and a proportional increase with the contents of ash, Ca, Mn, and Si, although the correlations were not strong and may not explain earthworm preference. Other physicochemical properties of the biochars, such as the % volatile C, % H, porosity, and cumulative surface area, were associated with increased aerobic bacteria and fluorescent pseudomonads in soil, but not associated with biochar removal by earthworms. More research is needed to determine if tailoring specific biochars for surface removal by earthworms could be achieved by supplementing biochar with Ca, Mn, and Si and thus lead to a non-disruptive system for delivery of biochar into lower soil horizons of perennial crops. More importantly, this procedure may be useful in screening biochars for attractiveness to earthworms.

Enzymatic saccharification and structural properties of industrial wood sawdust: Recycled ionic liquids pretreatments

Wood residues constitute a promising challenge for biochemical processing into bioethanol and chemicals with competitive costs. Here, we report the impacts of pretreatments in a hydrophilic ionic liquid ([C2mim][OAc]), onto the physicochemical properties and enzymatic saccharification of softwood (spruce) and hardwood (oak) sawdust. Enzymatic saccharification of IL- pretreated sawdust is significantly increased (up to 7 times) when compared to untreated ones. Methanol, ethanol or water can be used as polar anti-solvent for the recovery of a cellulose rich fraction after dissolution in IL (i.e regeneration step) without any effect on enzymatic saccharification. Chemical, textural and structural modifications possibly induced by the IL pretreatments have been investigated through various means (Infra-red spectroscopy, NMR, X-ray diffraction) in order to correlate the observed modifications in enzymatic saccharification. This mild pretreatment seemed to mainly act in a breakdown of lignocellulosic organization leading to better cellulase accessibility to cellulose thanks to the expansion of the powder and the creation of a large porous volume (5 times more apparent porous volume). Partial removal of lignin and extractives may also contribute to the best enzymatic performances. The recyclability and reuse up to 7 times of [C2mim][OAc] is shown without the need of strictly anhydrous conditions and any alteration of the pretreatment.

Unraveling the structural characteristics of lignin in hydrothermal pretreated fibers and manufactured binderless boards from Eucalyptus grandis

AbstractBackgroundEucalyptus grandisis one of the most abundant biomass from plantation in many parts of the world. The binderless board were manufactured from hydrothermal pretreated fibers ofEucalyptuswood and characterized for the chemical analyses and mechanical strengths in order to assess the mechanism of self-bonding. To make clear the self-bonding mechanism of these binderless boards, the structural characteristics of cellulolytic enzyme lignin (CEL) isolated fromEucalyptuswood, its hydrothermal pretreated fibers, and binderless boards were thoroughly investigated by chemical and spectroscopic methods.ResultsThe result revealed that hydrothermal pretreatment and hot pressing process could change cellulose crystalline structures by disrupting inter/intra hydrogen bonding of cellulose chains. During the hydrothermal pretreatment ofEucalyptuswood, acid-catalyzed cleavage of β-O-4′ linkages and ester bonds were the major mechanisms of lignin cleavage. This degradation pathway led to a more condensed lignin which has a high average molecular weight and more phenolic hydroxyl groups than the control. The hot pressing process resulted in the binderless boards with reduced lignin contents and decreased the glass transition temperature, thus making the lignin more accessible to the fiber surface. CEL isolated from the binderless boards showed an increased syringyl to guaiacyl propane (S/G) ratio but a lower molecular weight than those of the untreatedEucalyptuswood and the hydrothermal pretreated fibers.ConclusionsBased on the finding of this study, it is suggested that the combination of hydrothermal pretreatment and hot pressing process is a good way for conditioning hardwood sawdust for the production of binderless boards. The thermal softening of lignin, rich in phenolic hydroxyl groups, and increased condensed lignin structure contributed to the self-bonding formation of lignocellulosic materials.

Effects of Soil Amendments on the Abundance of a Parasitic Weed, Yellow Rattle (Rhinanthus minor) in Hay Fields

Yellow rattle is a hemiparasitic weed that is becoming increasingly problematic in hay fields in the northeastern United States. The biomass of yellow rattle was assessed in two experiments in which commercially available soil amendments were applied to an infested hay field under no-till management. The amendments were applied in the fall of 2010 and 2011 and included wood ash, biochar, hardwood sawdust, lime, and K. Wood ash applied at a rate of 8,967 kg ha−1 (4 tons per acre) had the greatest suppressive effect and reduced yellow rattle biomass the following summer by 86 and 92% relative to the untreated control in Experiments 1 and 2, respectively. Two additional treatments included in Experiment 2, a doubled rate of wood ash and sawdust applied at a rate of 13,450 kg ha−1, also reduced yellow rattle biomass. No other treatments affected yellow rattle biomass. A partial least-squares regression (PLSR) analysis that included aboveground plant community and soil biochemical data explained only 42.4% of the variation in yellow rattle biomass, suggesting that the mechanisms responsible for the suppression of yellow rattle by wood ash and sawdust are complex. Amending hay fields with wood ash or sawdust may be an effective nonherbicide strategy for managing yellow rattle infestations. Additional research will be required to determine the mechanisms and generality of yellow rattle suppression by wood ash and sawdust amendments to the soil.

Environmental strategies to remove volatile aromatic fractions (BTEX) from petroleum industry wastewater using biomass

This work investigates the potentials of peat and angico hardwood sawdust to remove BTEX (benzene, toluene, ethylbenzene, and isomers of xylene) from the produced water discharged into aquatic systems during petroleum extraction. Peat and angico sawdust samples were pyrolyzed at 500 °C, and found to contain n-alkenes, n-alkanes and pentacyclic triterpenes (peat), and 4-methoxyphenol, 1,4-dimethoxyphenol and 1,3,4-trimethoxyphenol (angico sawdust). In batch experiments, the removal capacities using peat were 32.4%, 50.0%, 63.0%, 67.8%, and 61.8% for benzene, toluene, ethylbenzene, m, p-xylenes and o-xylene, respectively. This compared with removal capacities using angico sawdust of 20.2%, 36.4%, 52.8%, 57.8%, and 53.7% for these compounds respectively, demonstrating the superior performance of the peat.

Production of glucose from oil palm trunk and sawdust of rubberwood and mixed hardwood

Disposing of solid waste and demand of fossil fuel have become the great challenges in the 21st century. Malaysia as one of the top producers of palm oil and wooden furniture in the world is well positioned to take the challenge of the reuses of its enormous output of lignocellulosic biomass such as oil palm trunk, sawdust of rubberwood and sawdust of mixed hardwood generated from palm oil and furniture industries. Before these lignocellulosic biomasses can be used to produce fuel and major chemicals which are normally derived from petroleum, lignocellulosic materials have to be converted to glucose. Hence, it is a need to investigate the conversion efficiency and to determine the optimum conditions for the conversion of lignocellulosic materials to glucose. This present work is aimed to investigate the potential use of oil palm trunk, rubberwood sawdust and mixed hardwood sawdust as an alternative feedstock for lignocellulosic glucose production. This research also served to identify the optimum two-stage concentrated acid hydrolysis condition that can convert these three lignocellulosic biomasses to glucose efficiently. Two stages concentrated sulfuric acid hydrolysis process using different acid concentration and reaction time were performed on those lignocellulosic biomass samples. The optimum results for oil palm trunk, rubberwood and mixed hardwood sawdust were obtained by using 60% acid concentration reacted for 30 min during 1st stage hydrolysis and subsequently followed by another 60 min reaction time with 30% acid concentration during the 2nd stage hydrolysis. The results, showed that oil palm trunk has a higher glucose conversion yield than those of rubberwood sawdust and mixed hardwood sawdust.

Effects of Turning Frequency, Windrow Size and Season on the Production Of Dairy Manure/Sawdust Composts

On-farm composting offers the potential to significantly reduce problems associated with manure management including odors, pathogens, ground water pollution, and utilization costs. Three controllable variables that directly affect the efficiency of on-farm composting are weather, windrow size and windrow turning frequency. In temperate climates, low ambient temperatures and winter precipitation may lower composting temperatures and increase compost moisture contents, making composting rates harder to maintain. Windrow size directly impacts the depth of penetration of oxygen and the amount of compost exposed to high temperatures, potentially affecting composting rate. Windrow turning reduces moisture and temperature gradients within the compost windrows, but the benefits of frequent turning on composting rate have not been well documented. The objectives of this study were to understand the effects of these variables on composting rate, weight loss, volatile solids loss, moisture content, oxygen and temperature gradients, bulk density and particle size of unseparated dairy manure composted with hardwood sawdust (DM+S). Two composting windrow sizes (surface area to volume ratios of 0.9-1.1m2/m3 and 1.7-2.1m2/m3) and two turning frequencies (every three days and every ten days) in two different seasons (winter and summer) were evaluated. Results showed that the seasonal differences were primarily associated with compost moisture content, which varied as a function of ambient air temperature and humidity. Windrow size affected oxygen and temperatures in windrows. Before turning, the temperature averages (different depths) were significantly higher (p < 0.05) and oxygen concentrations averages were lower in the larger windrows (p > 0.1) than those observed in the smaller windrows. Turning frequency was positively correlated (r > 0.7) with bulk density, moisture and wet weight loss but not with volatile solid loss, particle size or oxygen and temperatures. Overall, the final compost properties (day 120) were very similar regardless of turning frequency, season or windrow size. In conclusion, dairy manure composted in larger windrows turned 3 times per month resulted in composts not significantly different than those made in smaller windrows turned 10 times per month.

Influence of different litter materials on cecal microbiota colonization in broiler chickens

A chicken growth study was conducted to determine if litter type influenced gut microbiota and performance in broilers. Seven bedding materials were investigated and included soft and hardwood sawdust, softwood shavings, shredded paper, chopped straw, rice hulls, and reused softwood shavings. Microbial profiling was done to investigate changes in cecal bacterial communities associated with litter material and age. Cecal microbiota were investigated at 14 and 28 d of age (n = 12 birds/litter material). At both ages, the cecal microbiota of chickens raised on reused litter was significantly (P < 0.05) different from that of chickens raised on any of the other litter materials, except softwood shavings at d 28. Cecal microbiota was also significantly different between birds raised on shredded paper and rice hulls at both ages. Age had a significant influence on cecal microbiota composition regardless of litter material. Similarity in cecal microbial communities among birds raised on the same litter treatment was greater at 28 d of age (29 to 40%) than at 14 d of age (25 to 32%). Bird performance on the different litter materials was measured by feed conversion ratio, live weight, and feed intake. Significant (P < 0.05) differences were detected in live weight at 14 d of age and feed intake at 14 and 28 d of age among birds (n = 160/treatment) raised on some of the different litter materials. However, no significant (P > 0.05) differences were observed in feed conversion ratio among birds raised on any of the 7 different litter materials at either 14 or 28 d of age. The type of litter material can influence colonization and development of cecal microbiota in chickens. Litter-induced changes in the gut microbiota may be partially responsible for some of the significant differences observed in early rates of growth; therefore, litter choice may have an important role in poultry gut health particularly in the absence of in-feed antibiotics.

Preparation and characterization of composites comprising modified hardwood and wood polymers/poly(vinyl chloride)

Chemical modification of hardwood sawdust from ash-tree species was carried out with a solution of maleic anhydride in acetone. Wood polymers, lignin, and cellulose were isolated from the wood sawdust and modified by the same method. Samples were characterized by Fourier transform infrared spectroscopy (FTIR), providing evidence that maleic anhydride esterifies the free hydroxyl groups of the wood polymer components. Composites comprising chemically modified wood sawdust and wood polymers (cellulose, lignin)-as variable weight percentages-, and poly (vinyl chloride) were obtained and further characterized by using FTIR spectroscopy and scanning electron microscopy (SEM). The thermal behavior of composites was investigated by using the thermogravimetric analysis (TGA). In all cases, thermal properties were affected by fillers addition.

Effects of Composting On Removal of Nitrogen, Phosphorus, and Potassium from Sawdust Amended with Chicken Litter

A six month study evaluated composting affects on nitrogen (N), phosphorus (P), and potassium (K) leaching from hardwood and furniture sawdust amended with 20% and 30% chicken litter. Toxicity Characteristic Leaching Procedure (TCLP) was obtained from substrates. Moisture was provided through precipitation, and the substrate was aerated once or twice per week, depending on the amount of rainfall. Samples were collected at 45 day intervals for analysis. A significant reduction in N and K concentrations occurred for all amended compost by day 180. Hardwood substrate matured quicker than furniture compost based on a radish seed germination test. Toxicity reduction occurred in every treatment by day 180. Chicken litter control showed the best overall weight loss; however, its toxicity levels were still much higher on day 180.

Identification of Anti-Wood Rot Compounds in Teak (Tectona grandis L.f.) Sawdust Extract

The tropical hardwood sawdust of Tectona grandis L.f. from the wood processing industry was extracted and tested for anti-wood rot activity. Tectona grandis extract inhibited the brown rot fungi Gloeophyllum sepiarium, Gloeophyllum trabeum, Piptoporus betulinus and Serpula lacrymans, and the white rot fungi Bjerkandera adusta, Merulius tremellosus, and Phlebia brevispora. Centrifugal partition chromatography was used to separate these compounds using n-hexane-MeOH-H2O (50:47.5:2.5) as a solvent system. The compounds deoxylapachol, tectoquinone, 2-hydroxymethylanthraquinone, 3′-OH-deoxyisolapachol (2-[(1E)-3-hydroxy-3-methylbut-1-enyl]naphthoquinone), hemitectol (2,2-dimethyl-2H-benzo[h]chromen-6-ol), and tectol were isolated from Tectona grandis sawdust CHCl3-MeOH (1:1) extract. Deoxylapachol inhibited the brown rot fungi Gloeophyllum sepiarium CBS 353.74 and Gloeophyllum trabeum CBS 318.50 and the white rot fungi Merulius tremellosus CBS 280.73 and Phlebia brevispora CBS 509.92. Hemitectol together with tectol showed a high percentage of cellulase inhibition followed by 3′-OH-deoxyisolapachol and deoxylapachol.

Volatile organic compounds emitted from hardwood drying as a function of processing parameters

During the drying of wood, volatile organic compounds are emitted. These emissions contribute, in the presence of nitrogen oxides and sunlight, to the formation of ground level ozone and other harmful photo-oxidants. Emissions of volatile organic compounds from the drying of birch sawdust in a spouted bed were analyzed with a flame ionization detector and with a gas chromatograph-mass spectrometer. A D-optimal model of the emissions showed that the emissions increased exponentially with decreasing sawdust moisture content and that the final sawdust moisture content was influencing emissions about twice as much as the inlet drying medium temperature and the month of logging. At inlet temperatures of 140–170 °C, the emissions increased steeply when the moisture content of the sawdust reached 10%, whereas an inlet temperature of 200 °C caused a surge of thermal degradation products at 15% moisture content. The results of this study should help to reduce the emissions of volatile hydrocarbons during the drying of hardwood sawdust and wood chips.

Modified hardwood sawdust as adsorbent of heavy metal ions from water

The sawdust of oak and black locust hardwood was found to have good adsorption capacities for heavy metal ions. The leaching of coloured organic matters during the adsorption can be prevented by each of the following pre-treatments of adsorbents: with formaldehyde in acidic medium, with sodium hydroxide solution after formaldehyde treatment, or with sodium hydroxide only. The studies indicated that the leaching of coloured matters from modified hardwood sawdust was less than that from unmodified hardwood sawdust, namely between 70 and 94%, dependent on wood species and the method of modification. At the same time, adsorption capacities of modified adsorbents were higher than unmodified adsorbents when sodium hydroxide was applied for modification. When formaldehyde was applied for modification, the adsorption capacities of adsorbents remained unchanged. Only the application of sodium hydroxide was recommended for modification of hardwood sawdust.

SAFETY AND EFFICACY OF COMPOSTED BROILER LITTER IN MISSISSIPPI VEGETABLE PRODUCTION

Mississippi is one of the nation's largest broiler litter producing states. Interest in using litter and other organic waste products, such as compost, in horticultural systems is increasing in the state and region. The objective of this research was to determine the influences of composted broiler litter (CBL) on three aspects of vegetable crop productivity: growth and yield, microbiological safety, and mineral nutrition. This report focuses on the first two objectives. Compost was made in a covered, turned windrow for a blend of broiler litter and hardwood sawdust. Responses to CBL were tested in two vegetables: collard (Brassica oleracea var. Acephala) and tomato (Lycopersicon esculentum). Rates of CBL ranged from 0 to 5 tons/acre, preplant incorporated in a randomized complete block design with four replicates for each species in two separate experiments in 2004. Testing of the CBL, the soil after application, leaves, and harvested organs found no significant influence of CBL on pathogenic microbe concentrations. At each of five sampling dates through commercial crop maturity, collard (Brassica oleracea var. Acephala) fresh and dry weight per plant increased linearly with CBL applications up to 5 tons/acre. Tomato (Lycopersicon esculentum) shoot fresh weight increased with increasing CBL applications at each sampling date. Marketable fruit yield increased linearly with increasing CBL applications. Total fruit yield response to CBL was best described by a quadratic equation.

Preliminary Studies on Converting Agricultural Waste into Biodegradable Plastics. Part II: Corncobs

Hardwood sawdust was derivatized either by carboxymethylation, glutaration, maleiation, phthallation, or succination in order to produce anionic materials suitable for complexation with soy protein isolate. Blending each derivative with soy protein isolate resulted in instant precipitation of gels. Infrared spectroscopy and differential scanning calorimetry suggested that each derivative formed a complex with protein. Reaction products could be dried into pellets exhibiting tensile strengths between 0.9–2.4 MPa, suggested that these materials could be promising candidates for biodegradable structural materials.

Effects of Soil Carbon Amendment on Nitrogen Availability and Plant Growth in an Experimental Tallgrass Prairie Restoration

Abstract Restoration of tallgrass prairie on former agricultural land is often impeded by failure to establish a diverse native species assemblage and by difficulties with nonprairie, exotic species. High levels of available soil nitrogen (N) on such sites may favor fast‐growing exotics at the expense of more slowly growing prairie species characteristic of low‐N soils. We tested whether reducing N availability through soil carbon (C) amendments could be a useful tool in facilitating successful tallgrass prairie restoration. We added 6 kg/m2 hardwood sawdust to experimental plots on an abandoned agricultural field in the Sandusky Plains of central Ohio, United States, increasing soil C by 67% in the upper 15 cm. This C amendment caused a 94% reduction in annual net N mineralization and a 27% increase in soil moisture but had no effect on total N or pH. Overall, plant mass after one growing season was reduced by 64% on amended compared with unamended soil, but this effect was less for prairie forbs (−34%) than for prairie grasses (−67%) or exotics (−62%). After the second growing season, only exotics responded significantly to the soil C amendment, with a 40% reduction in mass. The N concentration of green‐leaf tissue and of senescent leaf litter was also reduced by the soil C treatment in most cases. We conclude that soil C amendment imparts several immediate benefits for tallgrass prairie restoration––notably reduced N availability, slower plant growth, and lower competition from exotic species.

Mass and Nutrient Losses During the Composting Of Dairy Manure Amended with Sawdust or Straw

Composting has become an increasingly popular manure management method for dairy farmers. However, the design of composting systems for farmers has been hindered by the limited amount of information on the quantities and volumes of compost produced relative to farm size and manure generated, and the impact of amendments on water, dry matter, volume and nitrogen losses during the composting process. Amendment type can affect the free air space, decomposition rate, temperature, C:N ratio and oxygen levels during composting. Amendments also initially increase the amount of material that must be handled. A better understanding of amendment effects should help farmers optimize, and potentially reduce costs associated with composting. In this study, freestall dairy manure (83% moisture) was amended with either hardwood sawdust or straw and composted for 110-155 days in turned windrows in four replicated trials that began on different dates. Initial C:N ratios of the windrows ranged from 25:1 to 50:1 due to variations in the source and N-content of the manure. Results showed that starting windrow volume for straw amended composts was 2.1 to 2.6 times greater than for sawdust amendment. Straw amended composts had low initial bulk densities with high free air space values of 75-93%. This led to lower temperatures and near ambient interstitial oxygen concentrations during composting. While all sawdust-amended composts self-heated to temperatures >55°C within 10 days, maintained these levels for more than 60 days and met EPA and USDA pathogen reduction guidelines, only two of the four straw amended windrows reached 55°C and none met the guidelines. In addition, sawdust amendment resulted in much lower windrow oxygen concentrations (< 5%) during the first 60 days. Both types of compost were stable after 100 days as indicated by CO2 evolution rates <0.5 mg CO2-C/g VS/d. Both types of amendments also led to extensive manure volume and weight reductions even after the weight of the added amendments were considered. However, moisture management proved critical in attaining reductions in manure weight during composting. Straw amendment resulted in greater volume decreases than sawdust amendment due to greater changes in bulk density and free air space. Through composting, farmers can reduce the volume and weights of material to be hauled by 50 to 80% based on equivalent nitrogen values of the stabilized compost as compared to unamended, uncomposted dairy manure. The initial total manure nitrogen lost during composting ranged from 7% to 38%. P and K losses were from 14 to 39% and from 1 to 38%, respectively. There was a significant negative correlation between C:N ratio and nitrogen loss (R2=0.78) and carbon loss (R2=0.86) during composting. An initial C:N ratio of greater than 40 is recommended to minimize nitrogen loss during dairy manure composting with sawdust or straw amendments.

Co-composting of Paper Mill Sludge and Hardwood Sawdust Under Two Types of In-Vessel Processes

Recycling of organic residues by composting is becoming an acceptable practice in our society. Co-composting dewatered paper mill sludge (PMS) and hardwood sawdust, two readily available materials in Canada, was investigated using uncontrolled and controlled in-vessel processes. The composted materials were characterized for total C and N, water-soluble, acid-hydrolyzable, and non-hydrolyzable N, extractable lipids, and by Fourier Transform Infrared (FT-IR) spectrophotometry. In the controlled scale process, the loss of organic matter was approximately 65% higher than in the uncontrolled process. After undergoing initial fluctuations in N fractions during the first two days of composting, by the end of the process, concentrations of water-soluble N decreased while those of acid-hydrolyzable and nonhydrolyzable N increased in the controlled process, whereas in the uncontrolled process, water-soluble N increased, but N in the other two fractions decreased continuously, indicating that the biochemical transformations of organic matter were not completed. Data on extractable lipids and FT-IR spectra suggest that the compost produced from the controlled process was bio-stable after 14 days, while the uncontrolled process was not stabilized after 18 days. In addition, FT-IR data suggest the biological activity during composting centered mainly on the degradation of aliphatic structures while aromatic structures were preserved. The co-composting of the PMS and hardwood sawdust can be successfully achieved if aeration, moisture, and bio-available C/N ratios are optimized to reduce losses of N.

Chemical changes during composting of a paper mill sludge–hardwood sawdust mixture

Recycling of paper mill sludge (PMS) by composting is becoming an acceptable practice for converting these chemically complex materials into useful soil amendments, while eliminating negative environmental impacts. The organic composition of a PMS–hardwood sawdust mixture was investigated during composting to better understand the changes in main chemical components. Pyrolysis-field ionization mass spectrometry (Py-FIMS) and cross polarization-magic angle spinning 13C nuclear magnetic resonance (CP-MAS 13C NMR) were employed to characterize the organic composition of the PMS composted materials. The spectroscopic data revealed that the major components of the PMS were lipids, sterols, lignin, N-compounds, and carbohydrates. By the end of composting (at biomaturity), concentrations of carbohydrates and lignin became more prominent, while those of lipids, sterols and proteinaceous components decreased. Increases in carbohydrates and decreases in paraffinic C, proteinaceous C and C in OCH 3 groups appeared to be related to increased microbial activity. Other chemical changes observed during composting were increases in aromatic C, phenolic C, and in aromaticity. While the total C and N contents decreased by about only 12.0%, the compost lost 50% of its initial weight. At biomaturity, the compost consisted primarily of polysaccharide/carbohydrate materials, specifically cellulose and acidic polysaccharides (uronic acids) in combination with smaller quantities of lignin.

Influence of organic and inorganic soil amendments on plant growth in crude oil‐contaminated soil

Phytoremediation can be a viable alternative to traditional, more costly remediation techniques. Three greenhouse studies were conducted to evaluate plant growth with different soil amendments in crude oil‐contaminated soil. Growth of alfalfa (Medicago sativa L., cultivar: Riley), bermudagrass (Cynodon dactylon L., cultivar: Common), crabgrass (Digitaria sanguinalis cultivar: Large), fescue (Lolium arundinaceum Schreb., cultivar: Kentucky 31), and ryegrass (Lolium multiflorum Lam., cultivar: Marshall) was determined in crude oil‐contaminated soil amended with either inorganic fertilizer, hardwood sawdust, papermill sludge, broiler litter or unamended (control). In the first study, the addition of broiler litter reduced seed germination for ryegrass, fescue, and alfalfa. In the second study, bermudagrass grown in broiler litteramended soil produced the most shoot biomass, bermudagrass produced the most root biomass, and crabgrass and bermudagrass produced the most root length. In the third study, soil amended with broiler litter resulted in the greatest reduction in gravimetric total petroleum hydrocarbon (TPH) levels across the six plant treatments following the 14‐wk study. Ryegrass produced more root biomass than any other species when grown in inorganic fertilizer‐ or hardwood sawdust + inorganic fertilizer‐amended soil. The studies demonstrated that soil amendments and plant species selection were important considerations for phytoremediation of crude oil‐contaminated soil.