Management alternatives of energy wood thinning stands

Energy wood thinning has become a feasible treatment alternative of young stands in Finland. Energy wood thinnings have been carried out mainly in stands where precommercial thinning has been neglected and the harvesting conditions for industrial wood thinning are difficult. Despite of its positive effects on harvesting costs and on renewable energy potential, whole-tree harvesting has been constantly criticized for causing growth loss. In this paper, the profitability of energy wood thinning was studied in 20 Scots pine-dominated stands where energy wood thinning was carried out. The growth of the stands after thinning was predicted with the help of Motti-stand simulator. Entire rotation time of the stands was simulated with different management alternatives. The intensity of first thinning and recovery level of logging residues varied between alternatives. In order to attain acceptable harvesting conditions, industrial wood thinning had to be delayed. The effect of energy wood thinning on subsequent stem wood growth was almost the same as in conventional thinning. Whole-tree harvesting for energy proved to be profitable alternative if the stumpage price is around 3€ m⁻³, the interest rate is 3% or 5% and the removal of pulpwood is less than 20 m³ ha⁻¹. If the harvestable pulpwood yield is over 20 m³ ha⁻¹, integrated harvesting of industrial and energy wood or delayed industrial wood harvesting becomes more profitable.     

Using modified foragers to harvest short-rotation poplar plantations

In Italy, short rotation coppice (SRC) has become very popular in recent years, with over 4000 ha already planted – almost exclusively with clonal poplar. Commercial harvesting operations are dominated by modified foragers, equipped with dedicated SRC headers. At present, contractors use two main header types: German Claas HS-2 and Italian GBE. The former fits smaller foragers with a power below 300 kW, the latter is used on larger harvest units. This study models the performance of modified foragers on a range of short-rotation poplar plantations. Data were collected from 45 operations, covering a total of 118 ha and producing over 4400 green tonnes of wood chips. The average yield of the fields harvested during the trials was about 23 gt ha^?1 year^?1 (at a moisture content of 59%), and machine productivity ranged from 9 to 70 green tonnes per scheduled machine hour (gt SMH^?1), with an average value of 35 gt SMH^?1. A model was developed to predict harvesting performance and cost, showing that harvesting cost can be maintained below the 15 € gt^?1 (2 € GJ^?1) level, if field stocking exceeds 40 gt ha^?1.     

Above-ground biomass production and nutrient accumulation in young stands of silver birch on abandoned agricultural land

During the last decade, more than 400 000 ha of agricultural land was abandoned in Estonia. Such areas are often characterized by rapid natural afforestation with silver birch, which has led to an increase both in the woodland area and in the area of silver birch stands. However, many bioenergetic aspects related to birch stands growing on arable land are still poorly understood. The main aim of the present study was to investigate the above-ground biomass production, nutrient (NPK) accumulation, and foliar characteristics of young silver birch stands on abandoned agricultural land. Five 8-year-old stands of silver birch growing on different soil types were included in the study.The density of the studied stands varied from 3060 to 36 200 trees per ha and their above-ground biomass varied from 6.0 to 22.9 t DM ha⁻¹. The largest share in the above-ground biomass of the birches (59–80%) was from the stems. The mean stem mass of the birches ranged from 0.29 to 1.79 kg, and the mean total above-ground biomass ranged from 0.36 to 3.03 kg. The leaf area index for the studied stands varied from 1.21 to 4.64 m² m⁻², being the highest for the stand of medium density. Mean single leaf area varied from 9.4±0.2 to 15.4±0.3 cm², leaf weight per area varied from 61.1±0.4 to 77.5±0.5 g m², and specific leaf area varied from 13.2±0.1 to 16.8±0.1 m² kg⁻¹. However, no significant differences were found between stand density and the foliar characteristics. There was a strong positive correlation between soil nitrogen concentration and leaf nitrogen concentration (R=0.92); regarding phosphorus concentration, the corresponding correlation was weak (R=0.52) and regarding potassium concentration, no significant correlation was found. The amount of nitrogen accumulated in the above-ground part of the silver birch stands varied between 42.4 and 145.8 kg ha⁻¹, the amount of phosphorus, between 5.9 and 27.9 kg ha⁻¹, and the amount of potassium, between 7.2 and 78.6 kg ha⁻¹. The N:P:K ratios for the foliage were comparable. It is evident that the proportion of nitrogen and phosphorus are close to optimum, while the N:K ratio was lower than optimum value in all cases.     

Mechanized coppice harvesting with new small-scale feller-bunchers: Results from harvesting trials with newly manufactured felling heads in Italy

The revival of coppice management is being considered as one option to satisfy the increasing market demand for wood biomass. Commonly used harvesting systems in coppice forests (CF) are based on motor manual felling, but further mechanization of CF operations is desirable because of increasing labor costs and the high fatality rates associated with motor manual felling.The goal of this study was to determine the machine performance in terms of productivity, cost-effectiveness and cut quality of new feller-bunchers, when used on different types of CF. The study comprised of five tests on different sites in Italy, four of which represented a specific type of CF.Results showed that harvesting productivity varied from 3.1 to 8.6 dry t per scheduled machine hour (SMH) in multi-stem coppice stands (4.5–16 dry m³ SMH⁻¹). Productivity reached 16.2 dry t SMH⁻¹ in a short rotation forestry (SRF) control stand (39.4 dry m³ SMH⁻¹) and it increased with stump mass. Recorded productivities tested in conventional CF were not as high as achieved in single-stem SRF, or in the mechanized felling of comparable softwood stands, but still matched the requirements of commercial mechanized logging. Costs varied between 3.57 and 20.56 € dry t⁻¹ (1.47–14.17 € dry ${\text{m}}^{3^{\mathrm{-}1}}$). Lowest costs were reached in the SRF stand and highest cost in the Mediterranean CF growing on moderate to steep terrain. Shear heads produced poor cuts and single-action shears performed worst. The disc saw produced very low cuts with low damage levels, which might be acceptable even under current cut quality specifications.     

Aboveground tree biomass in a recovering tropical sal (Shorea robusta Gaertn. f.) forest of Eastern Ghats,India

Aboveground biomass of individual tree species by component and total biomass per unit area for four different stages of a recovering tropical dry deciduous forest stands, dominated by sal (Shorea robusta Gaertn. f.) of the Eastern Ghats, India were investigated during 2001–2002. Different periods of recovering (2, 4, 6, and 10-year) forest stands (84°13′E, 20°29′N) were selected in the Kandhamal district of Orissa, India and sample trees of all species were harvested. Tree species diversity was 23, 23, 21 and 22 in 2, 4, 6, and 10-year recovering stands, respectively. Species-wise Ixora pavetta showed the highest biomass in 2 and 4-year stands while Shorea robusta in 6 and 10-year stands. Component-wise, in all species, bole–wood contribution ranged between 22.6% and 60.9%. Aboveground tree biomass, in all the stands, was dominated by Shorea robusta, which ranged between 12.68 and 231.91 Mg ha⁻¹. Total aboveground tree biomass was 30.12, 49.21, 107.54 and 261.08 Mg ha⁻¹ in 2, 4, 6 and 10-year stands, respectively.     

The economical and environmental performance of miscanthus and switchgrass production and supply chains in a European setting

The purpose of this study is to analyse the economical and environmental performance of switchgrass and miscanthus production and supply chains in the European Union (EU25), for the years 2004 and 2030. The environmental performance refers to the greenhouse gas (GHG) emissions, the primary fossil energy use and to the impact on fresh water reserves, soil erosion and biodiversity. Analyses are carried out for regions in five countries. The lowest costs of producing (including storing and transporting across 100 km) in the year 2004 are calculated for Poland, Hungary and Lithuania at 43–64 € per oven dry tonne (odt) or 2.4–3.6 € GJ^?1 higher heating value. This cost level is roughly equivalent to the price of natural gas (3.1 € GJ^?1) and lower than the price of crude oil (4.6 € GJ^?1) in 2004, but higher than the price of coal (1.7 € GJ^?1) in 2004. The costs of biomass in Italy and the United Kingdom are somewhat higher (65–105 € odt^?1 or 3.6–5.8 € GJ^?1). The doubling of the price of crude oil and natural gas that is projected for the period 2004–2030, combined with nearly stable biomass production costs, makes the production of perennial grasses competitive with natural gas and fossil oil. The results also show that the substitution of fossil fuels by biomass from perennial grasses is a robust strategy to reduce fossil energy use and curb GHG emissions, provided that perennial grasses are grown on agricultural land (cropland or pastures). However, in such case deep percolation and runoff of water are reduced, which can lead to overexploitation of fresh water reservoirs. This can be avoided by selecting suitable locations (away from direct accessible fresh water reservoirs) and by limiting the size of the plantations. The impacts on biodiversity are generally favourable compared to conventional crops, but the location of the plantation compared to other vegetation types and the size and harvesting regime of the plantation are important variables.     

Feasibility assessment of poplar bioenergy systems in the Southern Europe

A detailed reliability assessment of bioenergy production systems based on poplar cultivation was made. The aim of this assessment was to demonstrate the Economic feasibility of implementing poplar biomass production for power generation in Spain. The assessment considers the following chain of energy generation: cultivation and harvesting, and transportation and electricity generation in biomass power plants (10, 25 and 50 MW). Twelve scenarios were analysed in accordance with the following: two harvesting methods (high density packed stems and chip production in the field), two crop distributions around the power plant and three power plant sizes. The results show that the cost of biomass delivered at power plant ranges from 18.65 to 23.96 € Mg^?1 dry basis. According to power plant size, net profits range from 3 to 22 million € per yr.Sensibility analyses applied to capital cost at the power plant and to biomass production in the field demonstrate that they do not affect the feasibility of these systems. Reliability is improved if benefits through selling CO₂ emission credits are taken into account.This study clears up the Economic uncertainty of poplar biomass energy systems that already has been accepted as environmentally friendlier and as offering better energetic performance.     

Estimation of chemical traits in poplar short-rotation coppice at stand level

In order to improve qualitative traits of harvestable biomass and enhance its conversion into second generation biofuels (e.g. bioethanol), much attention should be paid to manage woody-energy plantations. This work represents an attempt to estimate chemical composition of biomass at stand level in poplar plantations. Based on the relationship between chemical traits of stem cross-sections and the corresponding distribution of diameter classes within the whole plantations, three different harvesting cycles were compared in terms of biomass yield and chemical composition. Under 2-year rotation, the stand showed the lower biomass annual yield (11.7 tDM ha^?1 y^?1) and the lower cellulose (42.5%) and the higher lignin (22%) proportion. On the contrary, under the 4-year cutting cycle, annual yield was not only higher (18.4 tDM ha^?1 y^?1), but the biomass also presented the highest cellulose (51.6%) and the lower lignin (19%) share. These results suggest that different management practices, including the cutting cycle, may affect not only yields but also qualitative traits of harvestable biomass of poplar short-rotation coppice.     

The potential biomass for energy production in the Czech Republic

Biomass production is a promising alternative for the Czech Republic's (CZ) agricultural sector. Biomass could cover the domestic bio-energy demand of 250 PJ a⁻¹ (predicted for 2030), and could be exported as bio-fuels to other EU countries. This study assesses the CZ's biomass production potential on a regional level and provides cost–supply curves for biomass from energy crops and agricultural and forestry residues. Agricultural productivity and the amount of land available for energy crop production are key variables in determining biomass potentials. Six scenarios for 2030 with different crop-yield levels, feed conversion efficiencies and land allocation procedures were built. The demand for food and fodder production was derived from FAO predictions for 2030. Biomass potential in the CZ is mainly determined by the development of food and fodder crop yields because the amount of land available for energy crop production increases with increasing productivity of food and fodder crops. In most scenarios the NUTS-3 regions CZ020, 31 and 32 provided the most land for energy-crop production and the highest biomass potentials. About 110 PJ a⁻¹, mostly from agricultural and forestry residues, can be provided from biomass when the present Czech agricultural productivity is maintained. About 195 PJ a⁻¹ (105 PJ from energy crops) can be provided when production systems are optimised with regard to fertilizer regimes and 365 PJ a⁻¹ (290 PJ from energy crops) when the yield level of Dutch agriculture is reached. Costs for woody biomass decrease with increasing plantation yield and range between 2.58 and 4.76 € GJ⁻¹. It was concluded that Czech agriculture could provide enough biomass for domestic demand and for export if agricultural productivity is increased.     

Economics of willow growing in Northern Ireland

This paper reviews the e economics of short rotation coppice willow as an energy crop in Northern Ireland. Gross margins are presented for willow production and compared with, in the particular circumstances of Northern Ireland, equivalent outputs from grain production, lowland sheep and suckler cow production. The model used indicated a gross margin of £45 ha⁻¹ yr⁻¹ for a 12 tDM ha⁻¹ annual coppice crop without subsidies where the crop value was placed at £40 t⁻¹. This was equivalent to a 7 t winter wheat crop at £70 t⁻¹ and compared favourably with both lowland sheep and suckler cows.Currently the industry in Northern Ireland is at a very early stage of development and this imposes cost penalties on the pioneer growers. This situation is compared with the situation in Sweden where there is an established industry of 15,000 ha, where costs are significantly lower. Gross margin for the pioneer grower in Northern Ireland is about £100 ha⁻¹ yr⁻¹ less than for Swedish willow growers.     

Evaluation of integrated harvesting systems in pine stands of the southern United States

We investigated the addition of a small chipper to mechanized, tree-length harvesting systems to produce biomass chips from tops, limbs, and underbrush in planted southern pine stands. The systems were examined in three replicated studies involving clearcuts and thinnings in 2006 and 2007 in the US state of Georgia. Biomass from understory stems ranged from 8.3 to 59.0 green tonnes per hectare in the three studies. Chipping the limbs and tops of merchantable stems did not reduce the production of roundwood, but only produced 7–11 t ha^?1 of biomass. Harvesting understory biomass in addition to chipping limbs and tops worked well with clearcut harvests, but reduced roundwood production by 50% in thinnings. Small chippers added to roundwood operations appear to have limited potential in current market conditions, but should become a viable option as stronger markets for biomass chips develop.     

Long-term yield potential of switchgrass-for-biofuel systems

Limited information is available regarding biomass production potential of long-term (>5- yr-old) switchgrass (Panicum virgatum L.) stands. Variables of interest in biomass production systems include cultivar selection, site/environment effects, and the impacts of fertility and harvest management on productivity and stand life. We studied biomass production of two upland and two lowland cultivars under two different managements at eight sites in the upper southeastern USA during 1999–2001. (Sites had been planted in 1992 and continuously managed for biomass production.) Switchgrass plots under lower-input management received 50 kg N ha⁻¹ yr⁻¹ and were harvested once, at the end of the season. Plots under higher-input management received 100 kg N ha⁻¹ (in two applications) and were harvested twice, in midsummer and at the end of the season. Management effects on yield, N removal, and stand density were evaluated. Annual biomass production across years, sites, cultivars, and managements averaged 14.2 Mg ha⁻¹. Across years and sites, a large (28%) yield response to increased inputs was observed for upland cultivars; but the potential value of higher-input management for lowland cultivars was masked overall by large site×management interactions. Nitrogen removal was greater under the higher-input system largely due to greater N concentrations in the midsummer harvests. Management recommendations (cultivar, fertilization, and harvest frequency), ideally, should be site and cultivar dependent, given the variable responses reported here.     

The impact of sustainability criteria on the costs and potentials of bioenergy production – Applied for case studies in Brazil and Ukraine

The goal of this paper is to analyse the impact of the implementation of a certification system on the management system (costs) of and the availability of land (quantity) for bioenergy production. Twelve socio-economic areas of concern (food supply, child labour, (minimum) wages, employment, health care and education) and environmental areas of concern (soil erosion, depletion of fresh water resources, nutrient losses and soil nutrient depletion, pollution from chemicals and biodiversity) are included. Since there is no generally accepted definition of sustainability, a loose and strict set of criteria are defined. Short rotation coppice (SRC) production systems in Ukraine and South East Brazil in 2015 are taken as case studies. The results indicate that it seems feasible to produce biomass for energy purposes at reasonable cost levels and meeting strict sustainability criteria at the same time. The loose set of criteria has no impact on the costs of energy crop production, which are calculated to be 1.7 € GJ^?1 in Brazil and 2.1 € GJ^?1 in Ukraine. The strict set of criteria results in an increase of the costs of energy crop production by 42 % in Brazil and 14 % in Ukraine. In general, compliance with strict socio-economic criteria has a limited impact on the costs, because SRC is relatively labour extensive. Strict environmental criteria likely have a larger impact.     

Performance of simulated flexible integrated gasification polygeneration facilities,Part B: Economic evaluation.

This paper investigates the economics of integrated gasification polygeneration (IG-PG) facilities and assesses under which market conditions flexible facilities outperform static facilities. In this study, the facilities use Eucalyptus wood pellets (EP), torrefied wood pellets (TOPS) and Illinois #6 coal as feedstock to produce electricity, FT-liquids, methanol and urea. All facilities incorporate CCS. The findings show production costs from static IG-PG facilities ranging between 12 and 21 €/GJ using coal, 19–33 €/GJ using TOPS and 22–38 €/GJ using EP, which is above the average market prices. IG-PG facilities can become competitive if capital costs drop by 10%–27% for coal based facilities. Biomass based facilities will need lower biomass pellet prices or higher CO₂ credit prices. Biomass becomes competitive with coal at a CO₂ credit price of 50–55 €/t CO₂. Variations in feedstock, CO₂ credit and electricity prices can be offset by operating a feedstock flexible IG-PG facility, which can switch between coal and TOPS, thereby altering its electricity production. The additional investment is around 0.5% of the capital costs of a dedicated coal based IG-PG facility. At 30 €/t CO₂, TOPS will be the preferred feedstock for 95% of the time at a feedstock price of 5.7 €/GJ. At these conditions, FT-liquids (gasoline/diesel) can be produced for 15.8 €/GJ (116 $/bbl). Historic records show price variations between 5.7 and 7.3 €/GJ for biomass pellet, 1.0–5.6 €/GJ for coal and 0–32 €/t CO₂. Within these price ranges, coal is generally the preferred feedstock, but occasionally biomass is preferred. Lower biomass prices will increase the frequency of switching feedstock preference from coal to biomass, raising the desire for flexibility. Of the three investigated chemicals, an IG-PG facility producing FT-liquids benefits the most from flexibility. Our study suggests that if the uncertainty in commodity prices is high, a small additional investment can make flexible IG-PG facilities attractive.     

Nutrient removal and bio-energy production from Netley-Libau Marsh at Lake Winnipeg through annual biomass harvesting

The primary goal of this research study was to evaluate the concept of combining bio-power production and nutrient removal by yearly biomass harvesting during ice-covered periods at Netley-Libau Marsh on Lake Winnipeg. Depending on the extent of vegetation within the marsh on any given year, removal rates range from 1.026 to 1.368 kt (3.1–4.2% of total Red River loading to Lake Winnipeg) of total nitrogen and 188–227 t (3.8–4.7% of total loading) of total phosphorus by harvesting 60% of the marsh area and 75% of the emergent parts of the vegetation. The effective management of water levels within the marsh was critical for vegetation growth and diversity. Suggestions on biomass harvesting and utilization methods were provided and a number of technologies were examined for the conversion of the harvested biomass to energy. The power produced in these systems ranged from 1.75 to 4.71 MW and, for some of the technologies, usable cogeneration heat was produced as a potential added value. CO₂ emission credits of 55.07 kt y⁻¹ can be expected with possible additional GHG credits for methane and NO_x displacement.     

Feasibility of pico-hydro and photovoltaic hybrid power systems for remote villages in Cameroon

Pico-hydro (pH) and photovoltaic (PV) hybrid systems incorporating a biogas generator have been simulated for remote villages in Cameroon using a load of 73 kWh/day and 8.3 kWp. Renewable energy systems were simulated using HOMER, the load profile of a hostel in Cameroon, the solar insolation of Garoua and the flow of river Mungo. For a 40% increase in the cost of imported power system components, the cost of energy was found to be either 0.352 €/kWh for a 5 kW pico-hydro generator with 72 kWh storage or 0.396 €/kWh for a 3 kWp photovoltaic generator with 36 kWh storage. These energy costs were obtained with a biomass resource cost of 25 €/tonne. The pH and PV hybrid systems both required the parallel operation of a 3.3 kW battery inverter with a 10 kW biogas generator. The pH/biogas/battery systems simulated for villages located in the south of Cameroon with a flow rate of at least 92 l/s produced lower energy costs than PV/biogas/battery systems simulated for villages in the north of Cameroon with an insolation level of at least 5.55 kWh/m²/day. For a single-wire grid extension cost of 5000 €/km, operation and maintenance costs of 125 €/yr/km and a grid power price of 0.1 €/kWh, the breakeven grid extension distances were found to be 12.9 km for pH/biogas/battery systems and 15.2 km for PV/biogas/battery systems respectively. Investments in biogas based renewable energy systems could thus be considered in the National Energy Action Plan of Cameroon for the supply of energy to key sectors involved in poverty alleviation.     

A full economic analysis of switchgrass under different scenarios in Italy estimated by BEE model

Three different scenarios of switchgrass (Panicum virgatum L.) cultivation (high, mild and low) in two different environmental conditions (North and South Italy) were economically analysed by the computerized model BEE. The dataset was mostly generated from an 8.6 ha field of switchgrass planted in 2002 at the University of Bologna (North Italy). Annual equivalent costs (AEC) and break-even yield (BEY, i.e. the dry matter yield at which cost equals selling price) of each scenario were calculated to assess the feasibility of each scenario. AEC ranged from €511 to €1.257 ha⁻¹ being always higher in northern than southern regions. As expected, BEY varied to an extent depending on input levels. BEY was clearly higher under intensive cropping systems (H_S) compared to mild-(M_S) and low-input (L_S) scenarios. However, even for M_S or L_S, BEY generally exceeded the harvested yield. Therefore, we can conclude that, at the market price of €55 Mg⁻¹ (dry basis), switchgrass can be hardly grown both in North and South Italy. However, the biomass market price appeared surprisingly underestimated if compared to the unit energy price of crude oil, therefore a desirable increase of biomass price could be expected in the next few years. Sensitivity analysis showed that biomass price strongly affects BEY, and this was especially found in H_S. Furthermore, the differences in BEY between L_S and H_S clearly decreased with increasing market prices. Therefore, H_S could be better indicated than L_S at high market prices. Switchgrass was found to be more profitable than some conventional crops to an extent depending on the yield higher than BEY (Y_i). At the current biomass price, Y_i was from less than 1 Mg ha⁻¹ (maize and alfalfa) to more than 4 Mg ha⁻¹ (sugarbeet).     

Engineering,nutrient removal,and feedstock conversion evaluations of four corn stover harvest scenarios

Crop residue has been identified as a near-term source of biomass for renewable fuel, heat, power, chemicals and other bio-materials. A prototype one-pass harvest system was used to collect residue samples from a corn (Zea mays L.) field near Ames, IA. Four harvest scenarios (low cut, high-cut top, high-cut bottom, and normal cut) were evaluated and are expressed as collected stover harvest indices (CSHI). High-cut top and high-cut bottom samples were obtained from the same plot in separate operations. Chemical composition, dilute acid pretreatment response, ethanol conversion yield and efficiency, and thermochemical conversion for each scenario were determined. Mean grain yield in this study (10.1 Mg ha⁻¹ dry weight) was representative of the average yield (10.0 Mg ha⁻¹) for the area (Story County, IA) and year (2005). The four harvest scenarios removed 6.7, 4.9, 1.7, and 5.1 Mg ha⁻¹ of dry matter, respectively, or 0.60 for low cut, 0.66 for normal cut, and 0.61 for the total high-cut (top+bottom) scenarios when expressed as CSHI values. The macro-nutrient replacement value for the normal harvest scenario was $57.36 ha⁻¹ or $11.27 Mg⁻¹. Harvesting stalk bottoms increased stover water content, risk of combine damage, estimated transportation costs, and left insufficient soil cover, while also producing a problematic feedstock. These preliminary results indicate harvesting stover (including the cobs) at a height of approximately 40 cm would be best for farmers and ethanol producers because of faster harvest speed and higher quality ethanol feedstock.     

Effects of wood ash and nitrogen fertilization on Scots pine crown biomass

The crown biomass, being one of the most susceptible components of the above-ground tree biomass, could respond positively to environmental changes and temporary increase in nutrient availability. The influence of wood ash and nitrogen fertilization on crown biomass was studied in a 40-year-old Scots pine (Pinus sylvestris L.) stand growing on a Haplic Arenosol. The 36-model trees for the crown biomass measurements were sampled for 3 growing seasons after the application of 5.0 t wood ash ha⁻¹, 180 kg N ha⁻¹, 2.5 t wood ash ha⁻¹ plus 180 kg N ha⁻¹, and control (untreated plots). The masses of the current, 1-year-old and older needles and shoots, and branches were measured. A significant influence on the current year needles and shoots was found after the application of 180 kg N ha⁻¹ or 2.5 t wood ash ha⁻¹ plus 180 kg N ha⁻¹. When wood ash was applied in combination with nitrogen, an extra response tendency of the crown growth, especially of the top and the middle sections of the crown, was determined. However, there was no short-term influence of wood ash on crown biomass growth.     

Kudzu [Pueraria montana (Lour.) Merr. Variety lobata]: A new source of carbohydrate for bioethanol production

We determined the amount of standing biomass of kudzu (Pueraria montana var lobata) in naturally infested fields in Maryland and Alabama, USA. At each site, we evaluated the carbohydrate content of roots, stems, and leaves. For a third site from Georgia, we evaluated the carbohydrate content of kudzu roots of varying diameters. Belowground biomass in Alabama exceeded 13 t ha^?1, and contained an average of 37% fermentable carbohydrates (sucrose, glucose, and starch). Roots from Georgia of all size classes contained over 60% fermentable carbohydrates. Biomass and carbohydrate levels in roots from Maryland were low compared to plants growing in Alabama and Georgia, producing 5 t ha^?1 of roots with 20% non-structural carbohydrate. Stems from Alabama and Maryland contained 1–3% carbohydrates. Based on the yield and carbohydrate content, we estimate wild kudzu stands in Alabama and Georgia could produce 5–10 t ha^?1 of carbohydrate, which would rival carbohydrate production from maize and sugar cane fields. If economical harvesting and processing techniques could be developed, the kudzu infesting North America has the potential to supplement existing bioethanol feedstocks, which could be of significance to the rural economy of the southeastern USA.