Effects of biochar on dry matter production and competitive ability of Rumex obtusifolius L.

Der Stumpfblättrige Ampfer (Rumex obtusifolius L.) ist ein gefürchtetes Unkraut im intensiv bewirtschafteten Grünland. In dieser Studie wurde untersucht, ob die Biokohle durch eine Verminderung des pflanzenverfügbaren N-Gehaltes im Boden für die Ampfer-Regulierung ein­gesetzt werden kann. Dazu wurde ein Gefäßversuch im Freien durchgeführt. Der Stumpfblättrige Ampfer und zwei Gräser, Italienisches Raygras (Lolium multiflorum) und Wiesen-Knaulgras (Dactylis glomerata), wuchsen in Reinkultur. R. obtusifolius wurde auch in Mischungen mit L. multiflorum angesät. Die Zufuhr von Biokohle zum Boden bewirkte eine Verminderung der Konzentration an N, S, Ca und Mg in der oberirdischen Phytomasse bei allen Arten. Dies dürfte auf einen Verdünnungseffekt zurückzuführen sein. Die K-Konzentration nahm nur beim Stumpfblättrigen Ampfer im Vergleich zur Kontrolle zu. Der höhere K-Gehalt im Boden infolge Biokohle-Zufuhr dürfte dafür verantwortlich sein. Beim Stumpfblättrigen Ampfer war K und nicht N das wachstumslimitierende Nährelement. Ein hoher pflanzenverfügbarer K-Gehalt im Boden dürfte die Massenvermehrung des Stumpfblätt­rigen Ampfers im Grünland deutlich fördern. Durch die Zufuhr von Biokohle und dem daraus resultierenden höheren K-Gehalt im Boden hat das durchschnittliche Spross-Trockengewicht beim Stumpfblättrigen Ampfer um 247%, beim Italienischen Raygras um 65% und beim Wiesen-Knaulgras um 108% im Vergleich zur Kontrolle zugenommen. Durch interspezifische Konkurrenz mit L. multiflorum wurde R. obtusifolius im Sprosswachstum deutlich gehemmt. Die Biokohle hat die Wettbewerbs­fähigkeit des Stumpfblättrigen Ampfers nicht vermindert und kann daher auch nicht zur Ampfer-Regulierung eingesetzt werden. Die vorliegenden Untersuchungsergebnisse können als Grundlage für vorbeugende Maßnahmen zur Ampfer-Regulierung dienen. DOI: 10.5073/JfK.2016.08.03, https://doi.org/10.5073/JfK.2016.08.03Rumex obtusifolius L. (broad-leaved dock) is one of the most troublesome weeds in intensively managed grassland. This study investigated the potential of biochar (BC), produced from woody green waste residues, to support its control. For this purpose, a pot experiment was conducted out of doors in Austria. It was expected that R. obtusifolius could be controlled by reducing available N content in the soil. R. obtusifolius and two grass species, Lolium multiflorum and Dactylis glomerata, were grown from seeds in monocultures, respectively. Moreover, R. obtusifolius was grown in mixtures with L. multiflorum. Due to a pure BC addition to soil (3% by wt), the concentrations of N, S, Ca and Mg in the shoot biomass decreased relative to the control in all three species, suggesting a dilution effect. The K concentration, however, increased only in R. obtusifolius, indicating its high absorp­tion capacity for K. In R. obtusifolius, K rather than N was the most growth-limiting nutrient element. The K level in soil appears to be important in controlling its distribution. To prevent Rumex infestation and/or to reduce existing infestations, a high soil K supply should be avoided. The average shoot dry weight of all three species was significantly higher when BC was applied (by 247%, 65% and 108%, in R. obtusifolius, L. multiflorum and D. glomerata, respectively), presumably because of a better K supply in soil. R. obtusifolius responded to interspecific competition with L. multiflorum by a density-dependent reduction of its shoot growth. BC did not decrease the competitive ability of Rumex in mixtures with Lolium. It is concluded that the addition of woody green waste BC to soil is no successful strategy for controlling R. obtusifolius in grassland. However, the results of this study can serve as a basis for preventive measures to Rumex control. DOI: 10.5073/JfK.2016.08.03, https://doi.org/10.5073/JfK.2016.08.0

Preparation and characterization of novel magnesium composite/walnut shells-derived biochar for as and p sorption from aqueous solutions

Unidad de excelencia María de Maeztu CEX2019-000940-MElevated or unnatural levels of arsenic (As) and phosphorus (P) concentrations in soils and waterbodies from anthropogenic sources can present significant hazards for both natural ecosystems and human food production. Effective, environmentally friendly, and inexpensive materials, such as biochar, are needed to reduce mobility and bioavailability of As and P. While biochar features several physicochemical properties that make it an ideal contaminant sorbent, certain modifications such as mineral-impregnation can improve sorption efficiencies for targeted compounds. Here, we conducted sorption experiments to investigate and quantify the potential utility of magnesium (Mg) for improving biochar sorption efficiency of P and As. We synthesized a Mg-modified walnut shells-derived biochar and characterized its ability to remove As and P from aqueous solutions, thereby mitigating losses of valuable P when needed while, at the same time, immobilizing hazardous As in ecosystems. SEM-EDX, FTIR and elemental analysis showed morphological and functional changes of biochar and the formation of new Mg-based composites (MgO, MgOHCl) responsible for improved sorption potential capacity by 10 times for As and 20 times for P. Sorption efficiency was attributed to improved AEC, higher SSA, chemical forms of sorbates and new sorption site formations. Synthetized Mg-composite/walnut shell-derived biochar also removed >90% of P from real samples of wastewater, indicating its potential suitability for contaminated waterbody remediation

Biochar from Wood Chips and Corn Cobs for Adsorption of Thioflavin T and Erythrosine B

Biochars from wood chips (WC) and corn cobs (CC) were prepared by slow pyrolysis and used for sorption separation of erythrosine B (EB) and thioflavin T (TT) in batch experiments. Biochar-based adsorbents were extensively characterized using FTIR, XRD, SEM-EDX, and XPS techniques. The kinetics studies revealed that adsorption on external surfaces was the rate-limiting step for the removal of TT on both WC and CC biochar, while intraparticle diffusion was the rate-limiting step for the adsorption of EB. Maximal experimental adsorption capacities Q(maxexp) of TT reached 182 +/- 5 (WC) and 45 +/- 2 mg g(-1) (CC), and EB 12.7 +/- 0.9 (WC) and 1.5 +/- 0.4 mg g(-1) (CC), respectively, thereby indicating a higher affinity of biochars for TT. The adsorption mechanism was found to be associated with pi-pi interaction, hydrogen bonding, and pore filling. Application of the innovative dynamic approach based on fast-field-cycling NMR relaxometry indicates that variations in the retention of water-soluble dyes could be explained by distinct water dynamics in the porous structures of WC and CC. The obtained results suggest that studied biochars will be more effective in adsorbing of cationic than anionic dyes from contaminated effluents

Biochar standardization and legislation harmonization

It is a relatively new concept to use biochar as soil amendment and for climate change mitigation. For this reason, the national and supranational legislation in the EU is not yet adequately prepared to regulate both the production and the application of biochar. Driven by this “regulatory gap”, voluntary biochar quality standards have been formed in Europe with the European Biochar Certificate, in the UK with the Biochar Quality Mandate and in the USA with the IBI Standard which is intended to be used internationally. In parallel to this, biochar producers and biochar users in a number of EU countries were partly successful in fitting the new biochar product into the existing national legislation for fertilisers, soil improvers and composts. The intended revision of the EC Regulation 2003/2003 on fertilisers offers the opportunity to regulate the use of biochar at the EU level. This publication summarizes the efforts on biochar standardization which have been carried out by voluntary products standards and illustrates existing legislation in EU member states, which apply to the production and use of biochar. It describes existing and planned EU regulations, which impact biochar applications and it develops recommendations on the harmonization of biochar legislation in the EU.  First published online: 24 Jan 201

The different faces of Biochar: contamination risk versus remediation tool

This article reviews the different aspects of biochar as source and sink of organic and inorganic contaminants. Biochar can contain organic contaminants such as polycyclic aromatic hydrocarbons or heavy metals. As the distribution coefficients of the biochar especially for contaminants are high, the freely dissolved concentrations are low and with that also the bioavailability. The link between biochar’s inherent contaminants and toxicity to soil meso– and macro–fauna remains unclear, with data being often contradictory and influenced by feedstock and pyrolysis conditions. The biochar’s potential to remediate contaminated soils has mainly been addressed in lab studies, but rarely in the field. This far, results have been contradicting. Many studies reported successful immobilization of contaminants but some not. In summary, the ambivalent face of the biochar with regard to contaminants prevails. In future, long term field studies are needed to properly address the sustainability of biochar in this respect. First published online: 02 Feb 201

Effect Of Wood-Based Biochar And Sewage Sludge Amendments For Soil Phosphorus Availability

This study investigated the effects of two biochars (pyrolysed wood chips and garden clippings) on phosphorus (P) availability in a heavy-metal contaminated soil poor in phosphorus. Short-term 14-days incubation experiments were conducted to study how applications of biochars at different rates (1 and 5 %) in combination with (1:1) and without dried sewage sludge from a municipal waste water treatment plant (WWTP) affected the content of soil extractable P. For P-availability analyses deionized water, calcium acetate lactate (CAL), Mehlich 3 and Olsen extraction protocols were applied. In addition, the content of total and mobile forms of potentially toxic heavy metals (PTHM) was studied. Application of both biochars caused a significant decrease of PTHM available forms in sewage sludge amended soil samples. The concentration of total and available P increased with higher biochar and sewage sludge application rates

Biochar application to temperate soils: effects on nutrient uptake and crop yield under field conditions

The benefits of biochar (BC) application to fertile, non-acidic soils in temperate climate regions might not always be as evident as for highly weathered tropical soils. The aim of our study was to investigate the effects of BC on soil characteristics, nutrient uptake and crop yield in field experiments on two temperate soils (Cambisol and Chernozem) in Austria. Maize and wheat (Cambisol), and barley and sunflower (Chernozem) were grown in successive vegetation periods following different BC application rates (0, 24 and 72 t ha-1 at the start of the experiment), supplemented with identical mineral N supply in 33 m² plots. BC treatments showed varying impacts on nutrient uptake of the investigated crops. The first growing season in the Chernozem region was affected by a prolonged drought period, which resulted in positive effects of BC on soil water-holding capacity (WHC) and barley crop yield (+ 10%) for the 72 t ha-1 BC + N treatment compared to a control with identical nutrient supply but without BC. However, maize and wheat grain yield decreased by 46 and 70%, respectively, after the highest BC application rate (72 t ha-1) in an additional treatment without supplementary N-fertilisation. Still, even with high BC application rates we did not observe any adverse effects on crop yield and nutrient uptake, as long as the soil was supplied with sufficient N according to local agricultural practice

Ecological impacts of traditional crop plants - a basis for the assessment of transgenic plants

For risk assessment of transgenic higher plants, pursuant to European Union Directive 94/15/EEC, traits of the organism are important. To verify the assumption that behaviour of a plant can be predicted from its traits, the ecological impacts resulting from the cultivation of eleven non-transgenic crop species were studied. It was hardly possible to infer effects directly from traits. Ecological impacts of agricultural practices are more easily identifiable. Adverse effects linked to certain traits frequently correlate with maladjustment to local environmental conditions (e.g. climate). Less attention is paid to these effects within the scope of conventional risk assessment. It is concluded that: effects cannot be fully anticipated from phenotypic traits, although this is a prerequisite for the currently practised form of risk assessment; the significance of the parameters 'gene transfer' and 'invasiveness' is much lower in practice than indicated by their importance in risk assessment; and ecological impacts of major practical importance are not taken into account, because they concern agricultural practice. Limitation of risk assessment to impacts on ecosystems NOT used agriculturally leads to an unacceptable limitation of the scope of protection. Since only phenotypic traits are deemed significant for possible risk, restriction of risk assessment to transgenic plants seems inappropriate. The introduction of more "ecologically beneficial" breeding goals in terms of a prophylactic and extensive environmental protection is proposed in the long term, to allow more consistent regulations that do not place transgenic plants at a disadvantage. To partially relieve the current shortcomings, Annex II B of EU Directive 94/15/EEC could include (e.g.) a question about whether the genetic modification allows, promotes or requires changes in agricultural practice and possible environmental impacts resulting from practice that has been modified due to the new traits