Wood Ash Application Research Articles

Environmental impact assessment of wood ash utilization in forest road construction and maintenance — A field study

The ever increasing use of wood material as fuel for green energy production requires innovative, environmentally safe strategies for recycling of the remaining wood ash. Utilizing wood ash in forest road construction and maintenance to improve mechanical stability has been suggested as a feasible recycling option. To investigate the environmental impact of wood ash application in forest road maintenance, a two-year field experiment was conducted at two Austrian forest sites (Kobernausserwald (KO) (soil pH5.5) and Weyregg (WE) (pH7.7)) differing in their soil chemical properties. Two different ashes, one produced by grate incineration (GA) and the other by fluidized bed incineration in a mixture with 15vol% burnt lime (FBA), were incorporated in repeated road sections at a 15:85% (V/V) ash-to-soil rate. Leaching waters from the road body were collected and analyzed for 32 environmentally relevant parameters over two years. Upon termination of the experiment, sub-road soil samples were collected and analyzed for ash-related changes in soil chemistry. Even though a larger number of parameters was affected by the ash application at the alkaline site (WE), we observed the most pronounced initial increases of pH as well as Al, As, Fe, Mn, Ni, Co, Cu, Mo, and NO2− concentrations in leachates beneath GA-treated road bodies at Kobernausserwald due to the lower soil buffer capacity at this site. Despite the observed effects our results indicate that, when specific requirements are met (i.e. appropriate ash quality, sufficient soil buffer capacity below the road body, and single time-point ash incorporation within several decades), wood ash application in forest road construction is generally environmentally acceptable.

Use of different organic fertilizers on soil fertility improvement, growth and head yield parameters of cabbage (Brassica oleraceae L)

Field experiment was carried out in Akure in the rainforest zone of Nigeria to determine the effect of poultry manure, wood ash and rice bran on the soil fertility improvement, growth and head yield of cabbage (Brassica oleraceae L) in 2011 and 2012 cropping seasons. The three organic fertilizer treatments were applied each at 6 t/ha with a reference treatment NPK 15-15-15 applied at 300 kg/ha and a control treatment arranged in a randomized complete block design with three replicates. The results showed significant increases (P < 0.05) in the growth and head yield parameters of cabbage crop under the different organic fertilizers compared to the control treatment. The application of poultry manure resulted in the highest values of cabbage plant height, stem girth, leaf number, leaf area, head weight, head length and head girth followed by NPK 15-15-15, wood ash and rice bran, respectively. Cabbage head weight, head girth, head length, plant height, stem girth, leaf number and leaf area increased by 17, 18, 8,17, 19, 10 and 16 %, respectively, with application of poultry manure compared to NPK fertilizer. Also, these parameters increased by 23, 21, 13 29, 25, 17 and 45 % compared to the wood ash treatment. The highest values of soil pH, Ca and Mg were obtained under wood ash application, while the highest values of soil O.M and moderate values of soil P, K, Ca and Mg were obtained under poultry manure application. Moderate values of soil pH, K, Ca and low % N were also recorded under rice bran treatment. However, the highest K/Ca, K/Mg and P/Mg ratios of 93.1, 74.1 and 572.1, respectively, were obtained under NPK 15-15-15 fertilizer application compared to 2:1 K/Ca, 2:1 K/Mg and 16:1 P/Mg in rice bran treatment. The poultry manure applied at 6 t/ha gave the best results in improving soil fertility, growth and head yield of cabbage, and this was because of its balanced nutrient composition and the least C/N ratio.

Chemical and microbiological properties of alpine forest soils: Effects of pelletized ashes in a short-term trial

The application of wood ash to forest soils has been used to compensate nutrient loss and avoid soil and water acidification. Using ashes in a non-stabilized form might negatively affect forest ecosystems. Bearing this in mind, together with landscape restrictions and socio-economic parameters, it underlines the importance of using pelletized ashes as soil additives in alpine areas. Therefore, in this study we evaluated the effects of pelletized ashes on the chemical and microbiological properties of four soils representative for the central Alps [rendzic Leptosol (L), fibric Histosol (H), haplic Podzol (P), and dystric Cambisol (Cm)] in a microcosm trial during 22weeks. The following ash-pellet treatments were at a ratio equivalent to 2Mgha−1: pellets without any additive (A); or in combination with bark, compost, and digestate (B–D). A control without ashes (Ct) was also included.Weekly measurements of pH and electrical conductivity (EC) from the soil leachates were performed. A higher pH, relative to Ct, was found in treatment A for Podsol. Additionally, treatments B and C led to a pH rise in Leptosol. Electrical conductivity, total C and N, and inorganic N forms were not significantly affected by the pelletized treatments regardless the soil type. A similar trend was recorded for pH and EC levels from the leachate samples. A lower metabolic quotient (qCO2), relative to Ct, was recorded in Podsol following treatment A. However, when pellet ashes were applied in combination with digestate, a higher qCO2 than that in Ct was found for this type of soil, which might indicate a lower microbial C utilization efficiency and/or microbial stress. This latter treatment also resulted in a lower dehydrogenase activity in Podsol, whilst soil protease activity and N mineralization were not affected in any of the studied soils. We conclude that ash amendment in pellets form on certain soils improves their acidity levels without causing extreme effects.

Effect of wood ash application on the morphological, physiological and biochemical parameters of Brassica napus L.

The present study was conducted to determine the effect of wood ash application on different parameters of Brassica napus L. including seed germination, seedling growth, fresh and dry biomass, water content in seedlings, photosynthetic pigments, soluble sugars, total protein and cell viability. In addition, the effect of wood ash on soil microflora and accumulation of trace elements in seedlings were determined. The seeds of B. napus were grown at different doses of wood ash (0, 1, 10, 25, 50 and 100 g (wood ash)/kg (soil)) and the effect on various parameters was determined. Wood ash significantly inhibited seed germination at doses above 25 g/kg and there was no germination at 100 g/kg of wood ash. At lower concentrations of wood ash, most of the growth parameters of seedlings were stimulated, but at higher concentrations of wood ash most of the studied parameters were adversely affected. Wood ash was found to be very detrimental to B. napus when applied above 25 g/kg. Wood ash application resulted in an increased bioaccumulation of trace elements in seedlings of B. napus. Almost all trace elements were significantly higher in seedlings grown in wood ash above 10 g/kg as compared to the control. An increase in total microbial count was observed with wood ash treatment which was statistically significant at 1 and 10 g/kg of wood ash. It is concluded that at very high concentration, wood ash can be detrimental to plants; however, its application at lower application rate can be recommended.

Effects of Wood Ash on the Chemical Properties of Soil and Crop Vitality in Small Plot Experiments/ Fahamu hatása a talaj kémiai jellemzőire és a termény vitalitására egy kisparcellás kísérletben

Abstract Wood-burning power plants and heating plants produce a great amount of wood ash as a by-product of the combustion process. In 2009 we launched an experiment in which we examined the composition of ash, the nutrient supplying capacity of soil mixed with ash, and the availability of its constituents. In the spring of 2010, we conducted small plot experiments using wood ash applications equivalent to 0; 1; 2.5; 5 and 10 t of wood ash/ha, on slightly acidic clay loam soil using white mustard and rye grass as the test plants. The pH value of the soil rose in a statistically verifiable way as a result of the ash treatments. After the application of ash, the P2O5 and K2O-content of the soil rose significantly; the treatments also increased the magnesium and sulphur content of the arable soil as well as the level of Zinc among the microelements. However, none of the wood ash applications caused verifiable changes in the number of shoots, in the green mass, or in the height of test plants. The increased nutrient supply of the soil through the treatments was not reflected in the nutrient content of the plants during the first year.

Application of body size spectra to nematode trait-index analyses

Current trait-based indices of soil fauna for assessing soil quality rely on extensive knowledge of life history traits for hyper-diverse groups. We look at the effects of clear-cut forest harvesting and subsequent wood ash application on the free-living nematode community using trait-based indices and body size spectra. We test the hypothesis that body size is a unifying trait and that the body size spectra can be used to demonstrate changes in soil quality while overcoming taxonomic impediments. Undisturbed boreal forest floor soils were compared with clear-cut sites amended with zero, one-half calcium equivalent wood ash, equivalent calcium reintroduction, and twice calcium reintroduction. Total abundance, trait-based metrics for the Maturity Index, and two metrics of body size spectra were calculated. Nematode abundance was not a good indicator of soil disturbance, while traditional trait-based approaches (the summed Maturity Index) demonstrated predicted changes in community structure. Analysis of two types of body size spectra elucidated how the community had changed under disturbance, and revealed that smaller bodied organisms were lost under ash amended treatments compared to both clear-cut and undisturbed forest. Using the body size spectra for nematodes is a simple addition to current trait-based approaches that can supplement soil assessments for disturbance and quality without requiring taxonomic expertise.

ESTIMATION OF LOSSES IN STORED MAIZE CAUSED BY CORCYRA CEPHALONICA STAINTON IN SOUTHERN RAJASTHAN AND THEIR ECO- FRIENDLY MANAGEMENT.

ABSTRACT Corcyra cephalonica Stainton is a notorious pest of stored cereals and cereal commodities in India as well as in other tropical and subtropical regions of the world. An experiment was conducted on extent of damage of C. cephalonica in maize under different storage structures during, 2010-2011, revealed that the maximum infested grain samples (61.53%) were recorded from grain stored in loose storage during June-July, 2011. Whereas, infested grain samples were not found from the grain stored in metal bin during November-December, 2010. The maximum weight loss (7.46%) was recorded in grain samples collected from loose storage in Udaipur district during June-July, 2011. No weight loss in grains were recorded in the samples collected from metal bin in Chittorgarh and Udaipur district during November-December 2010. In the quantitative and qualitative studies conducted in the selected districts observed that the maximum germination (78.00%) and protein content (8.60%) were recorded in the samples collected from metal bin in Chittorgarh district during November-December, 2010, while maximum carbohydrate content (72.00%) was recorded in maize samples collected from metal bin in Rajsamand district during November-December 2010. The minimum germination (62.00%) and carbohydrate content (66.50%) were recorded in maize samples collected from loose storage in Udaipur district; whereas, minimum protein content (6.70%) was recorded from loose storage in Chittorgarh district during June-July 2011. The studies conducted on efficacy of different grain protectants against C. cephalonica revealed that the highest larval mortality (82.20%), pupal mortality (10.00%) and minimum adult emergence (6.00%) were recorded in case of application neem leaf powder at 10g/kg seed, after 40 days of release. Application of wood ash at 15g/kg seed was found least effective.

Effects of wood chip ash fertilization on soil chemistry in a Norway spruce plantation on a nutrient-poor soil

Harvest of forest biomass for energy production may lead to export of nutrients from the forest. Recirculation of nutrients from wood chip combustion by ash spreading in forests has been proposed as a means for counteracting the nutrient export. This study was carried out to examine the effect of wood chip ash application on soil chemistry in a 44-year-old Norway spruce (Picea abies) plantation on a nutrient-poor soil in Denmark and to investigate the effect of applying different ash types and doses. Soil samples were collected and analyzed 2.5years (3 growing seasons) after ash application. This study shows that, regardless of ash formulation, preparation or dose, application of wood ash to forest soil has a liming effect in the O-horizon manifested as an increase in CECe, BS and pH. This effect was not seen in the mineral soil within the time frame of this study. At the same time, an increase in Cd was found in the O-horizon, corresponding to the amount added in the ashes. Generally, no other increase in soil contents of the heavy metals was seen. Hardening of the wood ash did not decrease the chemical impact on the soil chemistry as compared to non-treated ash whereas an increase in ash application dose increases the liming effect.

Reduced global warming potential after wood ash application in drained Northern peatland forests

Past land use change has converted vast areas of Northern peatland by drainage to agricultural or forested land. This change often reduces the greenhouse gas (GHG) sink strength of peatlands or turns them even from sinks to sources, which affects the global climate. Therefore, there is a need for suitable mitigation options for GHG emissions from drained peatlands. Addition of wood ash to peatland forests has been suggested as such a measure, but the overall effect on the global warming potential (GWP) of these ecosystems is still unclear. In order to fill this knowledge gap, we investigated three drained peatland forests in Sweden that had been fertilized with wood ash and monitored stand growth as well as the GHG emissions from soil, i.e. net effluxes of carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O). Our results show that over the first five to eight years after wood ash application, tree growth was enhanced at all sites. This was accompanied by generally little changes in the GHG emissions. Overall, we found that wood ash application reduced the GWP of drained peatland forests. Even though that our study was limited to eight years after wood ash application, we can conclude that in the short term wood ash application may be a suitable mitigation option for GHG emissions from Northern drained peatland forests.

The application of wood ash as a reagent in acid mine drainage treatment

The paper deals with a possible utilisation of wood ash as a reagent in treating acid mine drainage (AMD) from opencast mining of brown coal. Wood ash samples were obtained having combusted deciduous and coniferous tree wood in a household furnace. The dominant mineral phases in wood ash are calcite, quartz, lime and periclase. The used AMD is characteristic of high contents of sulphates, iron, manganese, heavy metals and low pH. The AMD treatment process included dosing of wood ash to adjust pH values about 8.3 (a dose of 0.5gl−1) or calcium hydroxide (a dose of 0.2gl−1) for comparison. The reaction time was 20min. Dosing of wood ash in AMD resulted in an increase of pH in solution from 3.5 to 8.3, which caused the removal of metal ions mainly by precipitation, co-precipitation and adsorption. Comparing the application of Ca(OH)2 in AMD treatment, at an almost identical pH value the concentrations fell in both cases for Fe, Mn, As, Co, Cu, Ni, Zn, Mg, Al and Mo. Applying wood ash the drop was even more distinct in Mn, Zn and Mg. The results of sedimentation tests in an Imhoff cone confirm that the settling capacities of sludge using wood ash are significantly better than when using calcium hydroxide in acid mine drainage treatment.

Increased bioavailability of metals in two contrasting agricultural soils treated with waste wood-derived biochar and ash

Recycled waste wood is being increasingly used for energy production; however, organic and metal contaminants in by-products produced from the combustion/pyrolysis residue may pose a significant environmental risk if they are disposed of to land. Here we conducted a study to evaluate if highly polluted biochar (from pyrolysis) and ash (from incineration) derived from Cu-based preservative-treated wood led to different metal (e.g., Cu, As, Ni, Cd, Pb, and Zn) bioavailability and accumulation in sunflower (Helianthus annuus L.). In a pot experiment, biochar at a common rate of 2 % w/w, corresponding to ∼50 t ha(-1), and an equivalent pre-combustion dose of wood ash (0.2 % w/w) were added to a Eutric Cambisol (pH 6.02) and a Haplic Podzol (pH 4.95), respectively. Both amendments initially raised soil pH, although this effect was relatively short-term, with pH returning close to the unamended control within about 7 weeks. The addition of both amendments resulted in an exceedance of soil Cu statutory limit, together with a significant increase of Cu and plant nutrient (e.g., K) bioavailability. The metal-sorbing capacity of the biochar, and the temporary increase in soil pH caused by adding the ash and biochar were insufficient to offset the amount of free metal released into solution. Sunflower plants were negatively affected by the addition of metal-treated wood-derived biochar and led to elevated concentration of metals in plant tissue, and reduced above- and below-ground biomass, while sunflower did not grow at all in the Haplic Podzol. Biochar and ash derived from wood treated with Cu-based preservatives can lead to extremely high Cu concentrations in soil and negatively affect plant growth. Identifying sources of contaminated wood in waste stream feedstocks is crucial before large-scale application of biochar or wood ash to soil is considered.

Evaluation of liming properties and potassium bioavailability of three Atlantic Canada wood ash sources

Sharifi, M., Cheema, M., Mahoney, K., LeBlanc, L. and Fillmore, S. 2013. Evaluation of liming properties and potassium bioavailability of three Atlantic Canada wood ash sources. Can. J. Plant Sci. 93: 1209–1216. Wood ash has the potential to enhance productivity in agricultural systems by influencing soil pH and nutrient availability. The liming properties and fertility values of wood ash from three Atlantic wood ash sources were evaluated in this study. The liming properties were tested using three wood ash sources [JD Irving (IR), New Page (NP), and Brooklyn Power (BP)] and two local lime sources in an 8-mo incubation experiment at 25°C. Soil pH was measured 14 times during the incubation. Availability of potassium (K) in wood ash was evaluated in a greenhouse setting with a K-deficient soil using annual ryegrass as the test plant. Total plant K and P uptake and Mehlich-3 extractable K and P were used as predictors of nutrient bioavailability. Wood ash application increased soil pH to the maximum level within the first 50 d after application and stabilized soil pH for 8 mo. The measured effective calcium carbonate equivalent of ashes relative to Mosher lime average among two soils were in order of BP (32)&gt;IR (25)&gt;NP (16). About 96, 38, and 71% of total K in IR, NP and BP ash sources, respectively, were bioavailable for ryegrass in 115 d. Although soil was not P deficient, soil P bioavailability (Mehlich III extractable P) was enhanced by 14 and 48% in NP and BP wood ash treatments, respectively, whereas P bioavailability decreased by 24% in the IR ash treatment. The results clearly demonstrate that these sources of wood ash can be considered as an effective liming agent and source of K in agricultural production systems.

Evaluation of liming properties and potassium bioavailability of three Atlantic Canada wood ash sources

Sharifi, M., Cheema, M., Mahoney, K., LeBlanc, L. and Fillmore, S. 2013. Evaluation of liming properties and potassium bioavailability of three Atlantic Canada wood ash sources. Can. J. Plant Sci. 93: 1209-1216. Wood ash has the potential to enhance productivity in agricultural systems by influencing soil pH and nutrient availability. The liming properties and fertility values of wood ash from three Atlantic wood ash sources were evaluated in this study. The liming properties were tested using three wood ash sources [JD Irving (IR), New Page (NP), and Brooklyn Power (BP)] and two local lime sources in an 8-mo incubation experiment at 25°C. Soil pH was measured 14 times during the incubation. Availability of potassium (K) in wood ash was evaluated in a greenhouse setting with a K-deficient soil using annual ryegrass as the test plant. Total plant K and P uptake and Mehlich-3 extractable K and P were used as predictors of nutrient bioavailability. Wood ash application increased soil pH to the maximum level ...

Short Communication&lt;br&gt;&lt;br&gt;Use of Indigenous Crop Protection Practices among Legume Crop Farmers in North-Central Nigeria

Legumes occupy a special position in Nigeria’s agricultural landscape. Apart from being relatively affordable sources of protein, legumes have the unique ability of soil enrichment, thus making them suitable in most farming systems in Nigeria. Unfortunately, legume production suffers from several challenges, chief among which is pest and disease infestation. This study investigated the level, types, determinants, and perceived effectiveness of the use of indigenous crop protection practices (ICPPs) among legume farmers in north-central Nigeria. A four-stage random sampling procedure was used to select 327 respondents, consisting of farmers cultivating cow pea, pea nut, and soya bean in Benue, Kogi, and Kwara States. An interviewer-administered questionnaire was used to elicit data from respondents. The study identified major pests and diseases of legumes, noted a rising trend in infestation, and revealed that traditional crop protection practices preponderated over chemical application. However, 29% of respondents used a combination of both methods. The most widely used ICPPs were crop rotation, bush fallowing, cutting of infected plant parts; and application of pepper (Capsicum Annum), neem (Azadirachta Indica) extracts and wood ash to control pests. The use of ICPPs prediction profile featured respondents’ socio-economic and occupational variables. Farm size, income, and age exhibited significant correlations with use of the ICPPs. Convincingly, most respondents perceived the ICPPs to be more effective than chemicals, and that the ICPPs posed minimal risks. It is thus worthwhile to improve ICPPs and incorporate them into the mainstream of agricultural extension service delivery, especially among low-income and youth farmers in Nigeria Nigerian Journal of Technological Research

Soil and tree responses to the application of wood ash containing charcoal in two soils with contrasting properties

Mixed wood ash (MWA), a mixture of fly ash and charcoal generated in power plants, could be used to replenish nutrients and organic matter in intensively managed soils. However, the response of the system will be determined by the soil properties, which will modify the interactions between soil components, microorganisms and plants.The study involved two young Pinus radiata plantations growing on soils that differed in texture, soil organic matter (SOM) and aeration. The soils were treated with MWA alone (a single dose of 4.5tonnesha−1 or three annual doses of 4.5 tonnes ha−1) or with MWA supplemented with P fertilizer (4.5Mg MWA plus 45kgPha−1). Analysis of the MWA revealed that the organic compounds in the ash were strongly aromatic. Although MWA is less reactive than fly wood ash, application of MWA enhanced the long-term nutrient availability and positively affected tree nutrition (mainly for P and K) and growth. Significant tree growth responses were recorded 3yr after the first application. Supplementation with mineral P fertilizer was not required with the larger amounts of MWA (×3 doses). Loss of elements by leaching was low, even in the sandy soil. The SOM content of the sandy soil increased in response to both treatments; this was attributed to the addition of charcoal but also to the higher SOM turnover in the litter. Microbial activity was enhanced in both soils, especially in the sandy soil.In conclusion, the soil response to the application of MWA is greatly influenced by the soil properties; the nutrient and SOM dynamics are directly affected by interactions between the ash and soil components and indirectly by soil biological activity and plant growth.

Soil C and N dynamics, nutrient leaching and fertility in a pine plantation amended with wood ash under Mediterranean climate

Wood ash addition to forest soils can balance exported nutrients by tree harvesting and decrease soil acidity, but its effectiveness in Mediterranean areas has been scarcely evaluated. The aim of the present study was to assess the effects of wood ash application on soil C and N dynamics, nutrient leaching and fertility in a pine stand. Treatments were loose and pelleted ash application (11 Mg ha−1), alone or combined with N fertilizer, and a control treatment. Nutrient leaching and soil chemical and biological properties were periodically evaluated for a 30-month period. Wood ash increased leaching of base cations (Ca, Mg, Na and K) and P, mainly at the beginning of the study. The effect was more pronounced for the loose formulation. As a consequence, a positive effect on soil nutrient availability (exchangeable base cations and extractable P) and soil acidity reduction was observed for the loose formulation in the 0–10-cm soil layer. Carbon and N dynamics were only affected when ash was applied with N fertilizer, which enhanced CO2 flux during the study period.

The response of methane and nitrous oxide fluxes to forest change in Europe

Abstract. Forests in Europe are changing due to interactions between climate change, nitrogen (N) deposition and new forest management practices. The concurrent impact on the forest greenhouse gas (GHG) balance is at present difficult to predict due to a lack of knowledge on controlling factors of GHG fluxes and response to changes in these factors. To improve the mechanistic understanding of the ongoing changes, we studied the response of soil–atmosphere exchange of nitrous oxide (N2O) and methane (CH4) at twelve experimental or natural gradient forest sites, representing anticipated future forest change. The experimental manipulations, one or more per site, included N addition (4 sites), changes of climate (temperature, 1 site; precipitation, 2 sites), soil hydrology (3 sites), harvest intensity (1 site), wood ash fertilisation (1 site), pH gradient in organic soil (1 site) and afforestation of cropland (1 site). On average, N2O emissions increased by 0.06 ± 0.03 (range 0–0.3) g N2O-N m−2 yr−1 across all treatments on mineral soils, but the increase was up to 10 times higher in an acidic organic soil. Soil moisture together with mineral soil C / N ratio and pH were found to significantly influence N2O emissions across all treatments. Emissions were increased by elevated N deposition, especially in interaction with increased soil moisture. High pH reduced the formation of N2O, even under otherwise favourable soil conditions. Oxidation (uptake) of CH4 was on average reduced from 0.16 ± 0.02 to 0.04 ± 0.05 g CH4-C m−2 yr−1 by the investigated treatments. The CH4 exchange was significantly influenced by soil moisture and soil C / N ratio across all treatments, and CH4 emissions occurred only in wet or water-saturated conditions. For most of the investigated forest manipulations or natural gradients, the response of both N2O and CH4 fluxes was towards reducing the overall GHG forest sink. The most resilient forests were dry Mediterranean forests, as well as forests with high soil C / N ratio or high soil pH. Mitigation strategies may focus on (i) sustainable management of wet forest areas and forested peatlands, (ii) continuous forest cover management, (iii) reducing atmospheric N input and, thus, N availability, and (iv) improving neutralisation capacity of acid soils (e.g. wood ash application).

Application of wood ash accelerates soil respiration and tree growth on drained peatland

Forested peatlands contain large pools of terrestrial carbon. As well as drainage, forest management such as fertilizer application can affect these pools. We studied the effect of wood ash (application rates 0, 5 and 15 t ha−1) on the heterotrophic soil respiration (CO2 efflux), cellulose decomposition, soil nutrients, biomass production and amount of C accumulated in a tree stand on a pine‐dominated drained mire in central Finland. The ash was spread 13 years before the respiration measurements. The annual CO2 efflux was statistically modelled using soil temperature as the driving variable. Wood ash application increased the amounts of mineral nutrients of peat substantially and increased soil pH in the uppermost 10 cm layer by 1.5–2 pH units. In the surface peat, the decomposition rate of cellulose in the ash plots was roughly double that in control plots. Annual CO2 efflux was least on the unfertilized site, 238 g CO2‐C m−2 year−1. The use of wood ash nearly doubled CO2 efflux to 420–475 g CO2‐Cm−2 year−1 on plots fertilized with 5–15 t ha−1 of ash, respectively. Furthermore, ash treatments resulted also in increased stand growth, and during the measurement year, the growing stand on ash plots accumulated carbon 11–12 times faster than the control plot. The difference between peat C emission and amount of C sequestered by trees on the ash plots was 43–58 g C m−2, while on the control plot it was 204 g C m−2. Our conclusion is that adding wood ash as a fertilizer increases more C sequestration in the tree stand than C efflux from the peat.

30-Year effects of wood ash and nitrogen fertilization on soil chemical properties, soil microbial processes and stand growth in a Scots pine stand

The effects of different doses of wood ash, given together with urea-N fertilizer, on chemical properties of the organic layer, soil microbial processes related to C and N cycling, and stand growth were studied in a Scots pine (Pinus sylvestris) stand on mineral soil 30 growing seasons after fertilization. The treatments were an unfertilized control, a nitrogen treatment (N) and a combined treatment with N and three different doses of wood ash: 1, 2.5 and 5Mgashha−1 (WA1+N, WA2.5+N and WA5+N). There were six replications in the control and N treatment and two replications in each ash+N treatment. The amount of N applied was 185kgha−1. Compared to the control, the WA5+N treatment significantly increased the pH (0.5 pH units) and decreased the exchangeable acidity in soil (45%). The concentrations of exchangeable Ca, K and Mg in the soil in the WA2.5+N and WA5+N treatments and those of extractable P in all the wood ash+N treatments were significantly higher than in the control and N-alone treatment. The Ca concentrations in the WA2.5+N were two times and in the WA5+N treatment three times that in the control treatment. The mean increment in basal area of the tree stand was significantly higher in the WA1+N and WA2.5+N treatments than in the control or N-alone treatment during the 30-year study period. Although application of wood ash increased the growth response to N, at the end of the study period the response had virtually stopped. To compare the statistical significance of the differences in microbial biomass and activities between different treatments, all six WA+N plots were combined, regardless of the different ash doses. Amounts of C and N in the microbial biomass, the rate of C mineralization (CO2 production) and concentration of K2SO4-extractable dissolved organic carbon were all higher in the WA+N treatment than in the N-alone treatment. The rate of net N mineralization, and the ratios between net N mineralization and C mineralization and between net N mineralization and microbial biomass N were all highest in the WA+N treatment, indicating better availability of N. In all treatments, however, both the rate of net nitrification and the NO3–N concentrations were negligible. In conclusion, wood ash application together with N seems to have very long-term effects on soil chemical properties and microbial processes in C and N cycling which give at least some explanations for the response in tree growth to this treatment.

Initial effects of wood ash application to soil and soil solution chemistry in a small, boreal catchment

With the conception that whole tree harvesting leads to an impoverishment of forest soils wood ash application is recommended, with the foremost benefits being increased pH in soil and subsequent surface waters, and recycling of nutrients from the wood ash.In this investigation a small boreal catchment in central Sweden was studied for 2years before and 2years after treatment with the maximum recommended dose, 3 tonnes/ha, of crushed, self-hardened wood ash. The sampling area was situated in a slope towards a stream, to include the effect on both recharge- and discharge areas with different soil constitutions. The soil solution chemistry, exchangeable pool of cations and potential heavy metal accumulation in berries were studied. Temporary increases in soil solution concentration were found for K in the recharge area and Ca and SO4 in the discharge area when comparing ashed and control areas. No change in exchangeable cations was observed during the study period, and no increase of heavy metals in bilberries did occur. These small changes in the constitution of the soil solution do not suggest wood ash application as a method to improve soil quality in an initial phase.