Effect of fertilization on the biomass production of coppiced mixed birch and willow stands on a cut-away peatland

This investigation deals with the biomass production of coppiced mixed birch and willow stands growing on a peat cut-away area at Aitoneva, Kihniö (62°12′N, 23°18′E), Finland. The 16-year-old stands were harvested and left to coppice for 14 years, fertilization experiment (control, PK and wood ash fertilization) with three replications was established after the clear cutting. The mother stands before clear cutting (11,000 stems per hectare on average) were dominated by silver birch (69% of the stem number). After clear cutting the number of stems rose 7-fold to 75 500 stems ha⁻¹. Now the stands were dominated by Betula pubescens with 46% out of the total stem number, the share of B. pendula being only 25% and with Salix spp 29%. At the age of 14 years self-thinning had decreased the stem number to 12,800 stems ha⁻¹. The leafless biomass production of the coppiced stands on the control plots was lower than that of the seed originated mother stands had been during the previous rotation. However, with fertilization the 14-year-old coppiced stands reached the same total production as the 16-year-old mother stands had reached. The foliar phosphorus concentrations showed a severe phosphorus deficiency on the controls. Fertilization increased biomass of the stands considerably. After 14 growing seasons the above-ground leafless dry-mass of the fertilized stands was 61.8 (PK-fertilization) and 61.4 t ha⁻¹ (Ash) and that of the control stands 37.6 t ha⁻¹. A single PK fertilizer application had increased the standing biomass by 24 t ha⁻¹ (64%). Even though fertilization increased biomass production it did not increase nutrient concentrations of wood and bark, but rather decreased them. Fertilization decreased the nitrogen concentrations of leafless above-ground biomass.     

Ground vegetation exceeds tree seedlings in early biomass production and carbon stock on an ash-fertilized cut-away peatland

Afforestation is one of the most popular after-use options of cut-away peatlands in Scandinavia since it has both economic and aesthetic values and therefore the interest concerning the carbon stock often focuses on tree stands. Consequently, ground vegetation is readily disregarded in the present calculations of the climatic impact of afforestation. However, at the early stages of afforestation vigorous ground vegetation may have a major role in carbon sequestration. The biomass and C stock of ground vegetation and young tree seedlings were examined on an ash-fertilized and afforested cut-away peatland. Six treatments of different mixtures and quantities of wood-ash, peat-ash, biotite or Forest PK-fertilizer were replicated in three plots. Betula pubescens Ehrh. seeds were sown on randomized halves of split plots while the other halves were left unsown. The plant biomass was harvested four growing seasons after the treatments. The live above-ground biomass of ground vegetation on a cut-away peatland was up to two times that of tree seedlings. Furthermore, the below-ground biomass of ground vegetation and tree seedlings was equal to the above-ground biomass, or even greater. In particular, the biomass of mosses multiplied on ash-based fertilized areas compared to the Forest PK-fertilized areas. Our study proved that at the early stages of afforestation ground vegetation was even more important in biomass production and C stock than tree seedlings. Consequently, our results suggest that ground vegetation biomass should also be considered when the climatic impact of afforestation of cut-away peatlands is being calculated.     

Effects of nutrient supply and soil cadmium concentration on cadmium removal by willow

This investigation studied the effect of an increased biomass production as a result of fertilization and an elevated Cd concentration in the topsoil on concentration and amount of Cd in two clones of Salix (81090 and 78183). The experiment was conducted over a three year period using 200-dm³ lysimeters filled with clay soil. A liquid fertilizer containing all essential macro- and micronutrients in balanced proportions by weight was applied at two rates according to growth. The lower rate corresponded to 0, 20 and 20 kg N ha⁻¹ during years 1, 2 and 3, respectively, while the higher rate was 30, 60 and 60 kg N ha⁻¹ for the same period. The Cd levels in the topsoil were an initial content of 0.3 mg Cd (kg dw soil)⁻¹ and 0.6 mg Cd (kg dw soil)⁻¹ after addition of CdSO₄.

Biomass production increased significantly due to fertilization. In general, this increase in biomass resulted in a higher Cd amount in the stem. However, the magnitude was small and only statistically significant in some cases, mainly because increased biomass also resulted in a lowered Cd concentration due to an effect of biological dilution. Addition of Cd to the topsoil resulted in higher Cd concentrations and total Cd amounts (concentration×biomass) in the Salix plants. In most cases the increase in total stem Cd amount was 40–80% of the increase in soil Cd concentration, although a directly proportional increase was observed occasionally. Clone 81090 had higher concentrations and total amounts of Cd in the stems than clone 78183, while clone 78183 produced more stem biomass. The leaves had the highest Cd concentrations, but the total amounts of Cd were largest in the stems.     

Impacts of paper sludge and manure on soil and biomass production of willow

Land application of organic wastes to short rotation woody crops (SRWC) can reduce the environmental impacts associated with waste disposal and enhance the productivity of biomass production systems. Understanding the potential impacts of organic amendments however, requires the examination of changes in soil characteristics and plant productivity. This study was conducted to evaluate the effect of paper sludge and dairy manure on biomass production of shrub willow (Salix dasyclados SV1) and to determine the impacts of these amendments on soil chemical properties. Treatments included urea, dairy manure and paper sludge separately and in combination, and a control. These materials were applied in the summer of 2005 to two fields of SV1 at different stages of growth: An old field with one year old shoots on a 10 year old root system and a young field which was beginning regrowth after being coppiced at the end of its first growing season. Foliar nutrient concentrations and soil chemical properties were analyzed at the end of the second growing season after treatment application to determine plant response to the fertilization regimes and to determine the effects of fertilization on soil characteristics. Fertilization did not increase biomass production in either field. However, application of the N-poor paper sludge did not reduce yield either. In general, fertilization did not influence soil or foliar chemistry, although there were some exceptions. The lack of response observed in this study is probably related to the nutrient status of the site or losses of applied nutrients.     

Effects of nutrient deprivation on biochemical compositions and photo-hydrogen production of Tetraselmis subcordiformis

Tetraselmis subcordiformis (formerly called Platymonas subcordiformis), a marine green alga, was previously demonstrated to photo-biologically produce hydrogen when treated with CCCP (Carbonyl Cyanide m-Chlorophenylhydrazone). The current results of our studies showed that there was a peak yield of hydrogen by T. subcordiformis at the stationary stage of its algal growth curve, suggesting that starvation of an essential element induced biochemical changes that enhanced hydrogen production by T. subcordiformis. Further investigation indicated that among nitrogen, sulphur and phosphorus (which are major components in the cultivation medium), nitrogen deprivation in the medium reduced the protein content inside the cells of T. subcordiformis, but increased the carbohydrate content over 4 times, resulting in 5.5 times increase in the hydrogen yield.     

Effect of fertilisation on biomass yield,ash and element uptake in SRC willow

Optimal fertilization of short rotation coppice (SRC) willow is important both in terms of economic yield and environmental effect. We measured biomass yield and nutrient uptake in two willow clones, Inger and Tordis, grown on a coarse sandy soil and within six different fertilization regimes. Fertilization treatments were carried out during two two-year harvest rotations, beginning in the 2nd growth year of the plantation. Willow was fertilized as follows with names referring to type of fertilizer and total quantities of nitrogen (kg ha⁻¹) in first and second year within both rotations: 1) Control₀₊₀, 2) NPK₁₂₀₊₀, 3) Slurry₁₈₀₊₀, 4) NPK_120+120, 5) NPK₂₄₀₊₀, 6) Slurry₃₆₀₊₀. Fertilization affected biomass yield significantly but interacted with rotation and clone. In first rotation, fertilization increased dry matter (DM) yield across clones significantly from 3.7 Mg ha⁻¹ y⁻¹ for Control₀₊₀ to 6.5, 6.4 and 5.6 for Slurry₃₆₀₊₀, NPK_120+120 and NPK₂₄₀₊₀, respectively. In second rotation, yield increased from 6.2 Mg ha⁻¹ y⁻¹ to 8.8, 8.2, 7.8 and 7.4 for Slurry₃₆₀₊₀, NPK₂₄₀₊₀, Slurry₁₈₀₊₀ and NPK_120+120, respectively. Biomass dry matter yield per ha increased linearly at 15 kg kg⁻¹ of applied total-N in both rotations. The yield increase in response to fertilization was generally larger in Inger than in Tordis. In general, element concentration in the harvested biomass was either unaffected or slightly reduced by fertilization. In conclusion, yield response to fertilization appears to be primarily related to the quantity of N applied but the effect depended on fertilizer type, harvest rotation and willow clone.     

Experimental studies on cofiring of coal and biomass blends in India

Concerns regarding the potential global environmental impacts of fossil fuels used in power generation and other energy supplies are increasing worldwide. One of the methods of mitigating these environmental impacts is increasing the fraction of renewable and sustainable energy in the national energy usage. A number of techniques and methods have been proposed for reducing gaseous emissions of NO_x,SO₂ and CO₂ from fossil fuel combustion and for reducing costs associated with these mitigation techniques. Some of the control methods are expensive and therefore increase production costs. Among the less expensive alternatives, cofiring has gained popularity with the electric utility producers. This paper discusses the ‘gaseous emission characteristics namely NO_x,SO₂, suspended particulate matter and other characteristics like specific fuel consumption, total fuel required, actual and equivalent evaporation, total cost of fuel, etc. from a 18.68 MW power plant with a travelling grate boiler, when biomass was cofired with bituminous coal in three proportions of 20%, 40% and 60% by mass. Bagasse, wood chips (Julia flora), sugarcane trash and coconut shell are the biomass fuels cofired with coal in this study.     

Productivity, aboveground biomass, nutrient uptake and carbon content in fast-growing tree plantations of native and introduced species in the Southern Region of Costa Rica

Early growth performance of four native and two introduced tree species was studied during six years at 13 sites in the southern region of Costa Rica. Selected study sites represent a wide environmental gradient.The selected species were: Pinus caribaea Morelet var hondurensis (Barret y Golfari) and Gmelina arborea Roxb as the introduced species, and Terminalia amazonia (J.F. Gmelin) Exell, Vochysia ferruginea Mart., Vochysia guatemalensis Donn. Sm. and Hieronyma alchorneoides Fr. Allemao. A study about the distribution of aboveground biomass, nutrients and total carbon content of these young plantations by compartments (branches, stem, bark and leaves) was also conducted. Biomass equations for tree compartments were fitted simultaneously using the data corresponding to 24 trees felled. Total export quantities of nutrient from stem and bark biomass were estimated in order to conduct an evaluation of the potential effect of harvesting these species on soil nutrient reserves. The data presented in this study related to plantation growth, aboveground biomass and nutrient concentration and C content by tree compartment, aboveground biomass equations by tree compartment, soil nutrient reserves, stability indices can be used as a reference for: a) selection of tree species vs site characteristics, b) estimation of nutrient export by stem + bark harvesting, c) planning for a second rotation, c) maintenance of site productivity and d) generate better carbon sequestration estimations.     

Efficient hydrogen gas production from cassava and food waste by a two-step process of dark fermentation and photo-fermentation

A two-step process of sequential anaerobic (dark) and photo-heterotrophic fermentation was employed to produce hydrogen from cassava and food waste. In dark fermentation, the average yield of hydrogen was approximately 199 ml H₂ g⁻¹ cassava and 220 ml H₂ g⁻¹ food waste. In subsequent photo-fermentation, the average yield of hydrogen from the effluent of dark fermentation was approximately 611 ml H₂ g⁻¹ cassava and 451 ml H₂ g⁻¹ food waste. The total hydrogen yield in the two-step process was estimated as 810 ml H₂ g⁻¹ cassava and 671 ml H₂ g⁻¹ food waste. Meanwhile, the COD decreased greatly with a removal efficiency of 84.3% in cassava batch and 80.2% in food waste batch. These results demonstrate that cassava and food waste could be ideal substrates for bio-hydrogen production. And a two-step process combining dark fermentation and photo-fermentation was highly improving both bio-hydrogen production and removal of substrates and fatty acids.     

A novel nutrient control method to deprive green algae of sulphur and initiate spontaneous hydrogen production

The green alga Chlamydomonas reinhardtii has the ability to produce clean and renewable molecular hydrogen through the biophotolysis of water. Hydrogen production takes place under anaerobic conditions, which may be imposed metabolically by depriving the algae of sulphur. Sulphur-deprivation typically requires the spatial and temporal separation of the algal growth and hydrogen production stages. This would typically require separate photobioreactors for each stage as well as a costly and energy intensive medium exchange technique such as centrifugation, making the process difficult to scale up.     

The effect of pH on the production of biohydrogen by clostridia: Thermodynamic and metabolic considerations

This study evaluates the effect of pH (4-7) on fermentative biohydrogen production by utilizing three isolated Clostridium species. Fermentative batch experiments show that the maximum hydrogen yield for Clostridium butyricum CGS2 (1.77 mmol/mmol glucose) is achieved at pH 6, whereas a high hydrogen production with Clostridium beijerinckii L9 (1.72 mmol/mmol glucose) and Clostridium tyrobutyricum FYa102 (1.83 mmol/mmol glucose) could be achieved under uncontrolled pH conditions (initial pH of 6.4-6.6 and final pH of 4-4.2). Low hydrogen yields (0-0.6 mmol/mmol glucose) observed at pH 4 are due likely to inhibitory effects on the microbial growth, although a low pH can be thermodynamically favorable for hydrogen production. The low hydrogen yields (0.12-0.64 mmol/mmol glucose) observed at pH 7 are attributed not only to thermodynamically unfavorable, but also metabolically unfavorable for hydrogen production. The relatively high levels of lactate, propionate, or formate observed at pH 7 reflect presumably the high enzymatic activities responsible for their production, together with the low hydrogenase activity, resulting in a low hydrogen production. A correlation analysis of the data from present and previous studies on biohydrogen production with pure Clostridium cultures and mixed microflora indicates a close relation between the hydrogen yield (YH₂) and the (YH₂)/(2(YHAc+YHBu)) ratio, with the observed correlation coefficient (0.787) higher than that (0.175) between YH₂ and the molar ratio of butyrate to acetate (B/A). Based on the (YH₂)/(2(YHAc+YHBu)) ratios observed at different pHs, a control of pH at 5.5-6.8 would seem to be an effective means to enhance the fermentative biohydrogen production.     

Biomass and root stem production of a colony-forming willow (Salix interior) on highly disturbed,low fertility sites

This study describes biomass production, colony formation, and clonal spread via root stems (RS) of a wide-ranging North American willow species, Salix interior Rowlee (INT), one of the few willows that spread via vegetatively reproduced colonies, which can result in hundreds of upright stems arising from a shallow horizontal root network. Eight INT clones were tested in a common-garden experiment on two distinct site types (shale rock overburden and coarse gravel erosion sediments) with very low nitrogen and nutrients on a former coal mine site. Survival, height growth, aboveground biomass, and number of root stems (NRS) were quantified following 3 years of growth after establishment as rootless stem cuttings. Clonal differences were significant for survival and height at age 3. Survival was significantly greater on the coarse gravel outwash than shale rock overburden after the first and third year, but differences were only significant in the first year. There was a significant positive relationship between height growth and survival, both of which are indicators of plant vigor. Analysis of clonal variation in NRS showed an intermediate level of significance (P = 0.083), and a significant clone by site interaction (P = 0.024). On coarse gravel outwash, the more vigorous clones for height growth also produced more RS, indicating the absence of a potential trade-off in carbohydrate resource allocation between height growth of the ortet (mother plant) and its capacity for colony formation and spread via RS. It appears that RS quickly become independent sources of carbohydrate production. However, there was no relationship between clonal height growth and NRS on the rock overburden. Loose sand and gravel outwash deposits promoted a more rapid spread of the shallow horizontal root network than the less penetrable shale rock overburden that dominates this former coal mine site.     

Improvement of fermentative biohydrogen production by Clostridium butyricum CWBI1009 in sequenced-batch,horizontal fixed bed and biodisc-like anaerobic reactors with biomass retention

A horizontal tubular fixed bed bioreactor (HFBR) and an anaerobic biodisc-like reactor (AnBDR) were designed to both fix Clostridium biomass and enable rapid transfer of the hydrogen produced to gas phase in order to decrease the strong effect of H₂ partial pressure and H₂ supersaturation on the performances of Clostridium strains. The highest H₂ production rate (703 mL H₂/L h) and yield (302 mL/g glucose consumed i.e. 2.4 mol/mol) with the pure culture were recorded in the AnBDR with 300 mL culture medium (total volume 2.3 L) at pH 5.2 and a glucose loading rate of 2.87 g/L h. These results are about 2.3 and 1.3-fold higher than those achieved in the same bioreactor with 500 mL liquid medium and with the same glucose consumption rate. Therefore, our experimentations and a short review of the literature reported in this paper emphasize the relevance of performing bioreactors with high L/G transfer.     

Biological hydrogen production of the genus Clostridium: Metabolic study and mathematical model simulation

The biochemical hydrogen potential (BHP) tests were conducted to investigate the metabolism of glucose fermentation and hydrogen production performance of four Clostridial species, including C. acetobutylicum M121, C. butyricum ATCC19398, C. tyrobutyricum FYa102, and C. beijerinckii L9. Batch experiments showed that all the tested strains fermented glucose, reduced medium pH from 7.2 to a value between 4.6 and 5.0, and produced butyrate (0.37–0.67 mmol/mmol-glucose) and acetate (0.34–0.42 mmol/mmol-glucose) as primary soluble metabolites. Meanwhile, a significant amount of hydrogen gas was produced accompanied with glucose degradation and acid production. Among the strains examined, C. beijerinckii L9 had the highest hydrogen production yield of 2.81 mmol/mmol-glucose. A kinetic model was developed to evaluate the metabolism of glucose fermentation of those Clostridium species in the batch cultures. The model, in general, was able to accurately describe the profile of glucose degradation as well as production of biomass, butyrate, acetate, ethanol, and hydrogen observed in the batch tests. In the glucose re-feeding experiments, the C. tyrobutyricum FYa102 and C. beijerinckii L9 isolates fermented additional glucose during re-feeding tests, producing a substantial amount of hydrogen. In contrast, C. butyricum ATCC19398 was unable to produce more hydrogen despite additional supply of glucose, presumably due to the metabolic shift from acetate/butyrate to lactate/ethanol production.     

Pulling effects of district heating plants on the adoption and spread of willow plantations for biomass: The power plant in Enköping (Sweden)

The development of the willow cultivation for bioenergy in the municipality of Enköping was analysed, with special attention to the changes in the capacity and use of wood fuels of the municipality’s combined power and heat plant, during the period 1986-2005. The evolution is compared with the municipality of Örebro, in Central Sweden, a pioneer in the use of willow plantations. The study was performed including the geographical location of all the plantations and owners using a GIS platform, and a methodology based on n-sigmoidal curves was proposed to study the adoption curves of willow before and after the changes in the district heating plant. The results show significant enlargements of the area planted with willow observed after the enlargement of the plant in 1994; most of these new plantations being located within 30 km from the plant. The method applied seems to be suited to explain the effects in adoption of the power plant. Around 28% of the growers seem to be attributed to the effects of the plant. The results of this study provide empirical evidence of the effect of the district heating systems on the development and promotion of willow plantations. The methodology provided can be valuable in understanding the success or failure of the energy programmes, from the farmer’s perspective, and can aid policy makers in achieving their goals.     

Hydrogen production of Enterobacter aerogenes altered by extracellular and intracellular redox states

Enterobacter aerogenes HU-101, tested for its hydrogen production in batch cultures on various substrates, produced the highest amount of hydrogen when the substrate was glycerol. The yield of hydrogen is a function of the degree to which the substrates are reduced. To examine the effect of intracellular redox state on hydrogen yield, glucose-limiting chemostat cultures were carried out at various pH using strain HU-101 and its mutant AY-2. For both strains, the molar yield and the production rate of hydrogen and the hydrogenase activity in the cell-free extract were optimal at the culture pH of 6.3. The highest NADH/NAD ratio in both strains was also observed at pH 6.3, at which the ratio in AY-2 was more than two-fold that of HU-101. Furthermore, NAD(P)H-dependent hydrogen formation was observed in the cell-free extract of AY-2, and hydrogenase activity was found not in the cytoplasmic but in the cell membrane fraction, suggesting that a high intracellular redox state, that is a high NADH/NAD ratio, would accelerate hydrogen production by driving membrane-bound NAD(P)H-dependent hydrogenase.     

Experimental studies on drying of Zingiber officinale, Curcuma longa l. and Tinospora cordifolia in solar-biomass hybrid drier

An integral type natural convection solar drier has been fabricated and coupled with a biomass stove. Experiments have been conducted to test the performance of the drier by drying of Zingiber officinale (ginger), Curcuma longa l. (turmeric) and Tinospora cordifolia (guduchi) during the summer climate in Delhi. It was found that, during the load test for ginger, 18 kg of fresh product with an initial moisture content of 319.74(db)% was dried to a final moisture content of 11.8(db)% within 33 h. Similarly, moisture content of turmeric and guduchi were reduced from 358.96 to 8.8 and 257.45 to 9.67(db)% during 36 and 48 h of drying, respectively. The drying of these products has also been studied under ‘solar-only’ and open sun in the same climatic conditions and the results indicate that for all the products, drying is faster, and is within 33–48 h in hybrid drier, against 72–120 h in ‘solar-only’ operation of the same drier and 192–288 h in open sun. Efficiency of the drier during its two mode (solar and biomass separately) of operation has been estimated and quality evaluation of under-studied products showed that developed drier is suitable for the drying of these products. The developed drier is a simple system, which can be manufactured locally and can be used for drying of other agricultural products.     

Assessment of the effects of hydrogen pressure on biomass pyrolysis: A study of Euphorbia Rigida, sunflower oil industrial waste and pure cellulose

To assess the effects of mass transfer and hydrogen pressure on the oil yield and quality from cellulosic biomass, fixed-bed pyrolysis (atmospheric pressure) and hydropyrolysis experiments at temperatures between 400 and 650°C have been conducted on sunflower bagasse and pure cellulose. The Euphorbia Rigida was extracted with n-hexane and methanol to remove low molecular mass terpenoids and saccharides so as to elucidate the extent of oil formation and aromatisation from the cellulosic structure. In contrast to coals and oil shales, oil yields from the sunflower bagasse were found to be largely independent of particle size (<1.8 mm) and sweep gas velocity with ca 35–40% w/w oil (dry basis) being obtained at 450–500°C. The use of high hydrogen pressures (> 50 bar) only gave rise to relatively small increases in oil yield but, expressed on a carbon basis, these increases are much greater due to the reduced the oxygen contents of the oils.