Wood ash residue causes a mixture of growth promotion and toxicity in Lemna minor

Contrasting environmental impacts of nano-biochar and conventional biochar on various organisms

The environmental hazards of nanobiochar (n-BC) require attention due to limited knowledge. This study is the first to explore the effects of biochar size reduction across various organisms, including bacteria (Allivibrio fischeri), plants (Lemna minor, Lepidium sativum), and invertebrates (Daphnia magna, Folsomia candida). Bulk biochar (b-BC) and n-BC were applied in both liquid and solid-phase tests to assess their ecotoxicity. The resulting leachates were tested at concentrations of 2, 10, and 100 mg/L on organisms such as Daphnia magna and Lemna minor. In the solid-phase tests, b-BC and n-BC were added to the OECD soil at concentrations of 1 % and 5 % to evaluate toxicity in Folsomia candida and at concentrations of 1 % to evaluate toxicity in Lepidium sativum. We found n-BC to be significantly more toxic (by 18 % to 2886 %) to A. fischeri than b-BC, with toxicity increasing over time. Low doses (1 %) of both b-BC and n-BC did not cause mortality or inhibit reproduction in F. candida, though b-BC enhanced reproduction (by 30 % to 56 %) compared to n-BC. At a 5 % dose, both b-BC and n-BC inhibited reproduction F. candida, with n-BC being 0.5 to 1.8 times more toxic. Neither b-BC nor n-BC immobilized D. magna, but both inhibited reproduction (by 28 % to 35 %). The nanoscale dimensions of n-BC facilitated bioaccumulation in D. magna, leading to adhesion on the organism's body. The n-BC had a greater impact on plants, both b-BC and n-BC were non-toxic to L. minor, but all n-BC inhibited root growth in L. sativum. These findings highlight the importance of considering biochar size, feedstock, and pyrolysis conditions when evaluating environmental risks, ensuring safe use in sustainable agriculture.

Increasing Fertilization Efficiency of Biomass Ash by the Synergistically Acting Digestate and Extract from Water Plants Sequestering CO2 in Sorghum Crops

The utilization of biomass ash in sustainable agriculture and increasing its fertilizing efficiency by biological agents, potentially sequestering CO2, have become important issues for the global economy. The aim of this paper was to investigate the effects of ash from sorghum (Sorghum bicolor L. Moench) and Jerusalem artichoke (Helianthus tuberosus L.) biomass, a biogas plant digestate, and a Spirodela polyrhiza extract, acting alone or synergistically, on soil fertility and the development, health and physiological properties of sorghum plants. The results show novel information concerning differences in the composition and impact of ash, depending on its origin, soil properties and sorghum plant development. Sorghum ash was more effective than that from Jerusalem artichoke. Ash used alone and preferably acting synergistically with the digestate and Spirodela polyrhiza extract greatly increased soil fertility and the growth, biomass yield and health of sorghum plants. These improvements were associated with an increased chlorophyll content in leaves, better gas exchange (photosynthesis, transpiration, stomatal conductance), greater enzyme activity (acid and alkaline phosphatase, RNase, and total dehydrogenase), and a higher biomass energy value. The developed treatments improved environmental conditions by replacing synthetic fertilizers, increasing the sequestration of CO2, solving the ash storage problem, reducing the need for pesticides, and enabling a closed circulation of nutrients between plant and soil, maintaining high soil fertility.

Ashes from challenging fuels in the circular economy

In line with the objectives of the circular economy, the conversion of waste streams to useful and valuable side streams is a central goal. Ash represents one of the main industrial side-products, and using ashes in other than the present landfilling applications is, therefore, a high priority. This paper reviews the properties and utilization of ashes of different biomass power plants and waste incinerations, with a focus on the past decade. Possibilities for ash utilization are of uttermost importance in terms of circular economy and disposal of landfills. However, considering its applicability, ash originating from the heat treatment of chemically complex fuels, such as biomass and waste poses several challenges such as high heavy metal content and the presence of toxic and/or corrosive species. Furthermore, the physical properties of the ash might limit its usability. Nevertheless, numerous studies addressing the utilization possibilities of challenging ash in various applications have been carried out over the past decade. This review, with over 300 references, surveys the field of research, focusing on the utilization of biomass and municipal solid waste (MSW) ashes. Also, metal and phosphorus recovery from different ashes is addressed. It can be concluded that the key beneficial properties of the ash types addressed in this review are based on their i) alkaline nature suitable for neutralization reactions, ii) high adsorption capabilities to be used in CO2 capture and waste treatment, and iii) large surface area and appropriate chemical composition for the catalyst industry. Especially, ashes rich in Al2O3 and SiO2 have proven to be promising alternative catalysts in various industrial processes and as precursors for synthetic zeolites.

Effects of Soil Amendment With Wood Ash on Transpiration, Growth, and Metal Uptake in Two Contrasting Maize (Zea mays L.) Hybrids to Drought Tolerance

Wood ash as a soil amendment has gained wide spread acceptance in the recent years as a sustainable alternative to chemical fertilizers, although information regarding the effects of its application on maize growth and yield in the context of climate change and increasing drought severity is lacking till date. In the present study, field and pot trials were carried out at the experimental farm of the University of Padova at Legnaro (NE Italy) in a silty-loam soil in order to investigate the effects of soil amendment with wood ash (0.1% w/w, incorporated into the 0.2-m top soil) on the bioavailability of mineral elements and their uptake by maize. Characteristics analyzed included plant growth, leaf transpiration dynamics, and productivity in two contrasting hybrids, P1921 (drought sensitive) and D24 (drought tolerant). Wood ash contained relevant amounts of Ca, K, Mg, P, and S, and hazardous levels of Zn (732 mg kg^-1), Pb (527 mg kg^-1), and Cu (129 mg kg^-1), although no significant changes in total soil element concentration, pH, and electrical conductivity were detected in open field. Ash application led to a general increasing trend of diethylene triamine penta-acetic acid (DTPA)-extractable of various elements, bringing to higher grain P in D24 hybrid, and Zn and Ni reductions in P1921 hybrid. Here, the results demonstrated that ash amendment enhanced shoot growth and the number of leaves, causing a reduction of harvest index, without affecting grain yield in both hybrids. The most relevant result was a retarded inhibition of leaf transpiration under artificial progressive water stress, particularly in the drought-tolerant D24 hybrid that could be sustained by root growth improvements in the field across the whole 0-1.5 m soil profile in D24, and in the amended top soil in P1921. It is concluded that woody ash can be profitably exploited in maize fertilization for enhancing shoot and root growth and drought tolerance, thanks to morphological and physiological improvements, although major benefits are expected to be achieved in drought tolerant hybrids. Attention should be payed when using ash derived by metal contaminated wood stocks to avoid any health risk in food uses.

Effects of Soil Amendment With Wood Ash on Transpiration, Growth, and Metal Uptake in Two Contrasting Maize (Zea mays L.) Hybrids to Drought Tolerance

Wood ash as a soil amendment has gained wide spread acceptance in the recent years as a sustainable alternative to chemical fertilizers, although information regarding the effects of its application on maize growth and yield in the context of climate change and increasing drought severity is lacking till date. In the present study, field and pot trials were carried out at the experimental farm of the University of Padova at Legnaro (NE Italy) in a silty-loam soil in order to investigate the effects of soil amendment with wood ash (0.1% w/w, incorporated into the 0.2-m top soil) on the bioavailability of mineral elements and their uptake by maize. Characteristics analyzed included plant growth, leaf transpiration dynamics, and productivity in two contrasting hybrids, P1921 (drought sensitive) and D24 (drought tolerant). Wood ash contained relevant amounts of Ca, K, Mg, P, and S, and hazardous levels of Zn (732 mg kg^-1), Pb (527 mg kg^-1), and Cu (129 mg kg^-1), although no significant changes in total soil element concentration, pH, and electrical conductivity were detected in open field. Ash application led to a general increasing trend of diethylene triamine penta-acetic acid (DTPA)-extractable of various elements, bringing to higher grain P in D24 hybrid, and Zn and Ni reductions in P1921 hybrid. Here, the results demonstrated that ash amendment enhanced shoot growth and the number of leaves, causing a reduction of harvest index, without affecting grain yield in both hybrids. The most relevant result was a retarded inhibition of leaf transpiration under artificial progressive water stress, particularly in the drought-tolerant D24 hybrid that could be sustained by root growth improvements in the field across the whole 0-1.5 m soil profile in D24, and in the amended top soil in P1921. It is concluded that woody ash can be profitably exploited in maize fertilization for enhancing shoot and root growth and drought tolerance, thanks to morphological and physiological improvements, although major benefits are expected to be achieved in drought tolerant hybrids. Attention should be payed when using ash derived by metal contaminated wood stocks to avoid any health risk in food uses.

Exploring the use of Dicranopteris pedata ash as a rare earth fertilizer to Ipomoea aquatica Forsskal

This study examines a new method to dispose the biomass of a rare earth elements (REE) hyperaccumulator, Dicranopteris pedata, as a REE containing additive of a basal fertilizer for agricultural application. The D. pedata laminas were calcinated to fabricate ashes. The total REE content was 2.65 % for AshDp500, and 4.12 % for AshDp815, respectively. However, as for the heavy metals, Cd or Pb, a higher content could be found in AshDp500 than in AshDp815. The elemental contents of D. pedata ashes are qualified for fertilizer application. Pot experiments were then conducted to investigate the effects of AshDp815 on both the yield and quality of Ipomoea aquatica Forsskal grown in a yellow brown earth, or in a red soil. The application of the ashes increased the I. aquatica height, biomass, vitamin C, soluble protein, and soluble sugar contents, but decreased the I. aquatica nitrate and free amino acids contents. Furthermore, none of the microelements of I. aquatica leaf exceeded the Chinese national standard. The observations indicate the favorable effect of using D. pedata ash on the growth of I. aquatica which is most likely the result from the fertilizer effects of both macroelements and REE present in the ash.