The way forward in biochar research: targeting trade‐offs between the potential wins

Biochar application to soil is currently widely advocated for a variety of reasons related to sustainability. Typically, soil amelioration with biochar is presented as a multiple‐‘win’ strategy, although it is also associated with potential risks such as environmental contamination. The most often claimed benefits of biochar (i.e. the ‘wins’) include (i) carbon sequestration; (ii) soil fertility enhancement; (iii) biofuel/bioenergy production; (iv) pollutant immobilization; and (v) waste disposal. However, the vast majority of studies ignore possible trade‐offs between them. For example, there is an obvious trade‐off between maximizing biofuel production and maximizing biochar production. Also, relatively little attention has been paid to mechanisms, as opposed to systems impacts, behind observed biochar effects, often leaving open the question as to whether they reflect truly unique properties of biochar as opposed to being simply the short‐term consequences of a fertilization or liming effect. Here, we provide an outline for the future of soil biochar research. We first identify possible trade‐offs between the potential benefits. Second, to be able to better understand and quantify these trade‐offs, we propose guidelines for robust experimental design and selection of appropriate controls that allow both mechanistic and systems assessment of biochar effects and trade‐offs between the wins. Third, we offer a conceptual framework to guide future experiments and suggest guidelines for the standardized reporting of biochar experiments to allow effective between‐site comparisons to quantify trade‐offs. Such a mechanistic and systems framework is required to allow effective comparisons between experiments, across scales and locations, to guide policy and recommendations concerning biochar application to soil.     

Book Review Section

This article argues that education policy should support school-university partnerships that place preservice music teachers with their college professors in a laboratory school environment. With roots in Dewey's experimental school of 1896, the laboratory concept is a variation of the professional development schools now in vogue. The policies recommended here are not tied directly to this school-university partnership model, but they do support the collaborative concept. Policy recommendations include re-conceptualization of the student teaching experience; compensation of faculty members through financial incentives and professional development credits; and consideration for university faculty members engaged in such partnerships when determining workload and reviewing teaching, scholarship, and service for tenure or promotion decisions. The policy recommendations call for the creation of release time for school personnel to meet with university personnel to plan and assess the partnered collaboration, and for funding to support ongoing collaborative research by university and school personnel.     

生物炭影响作物生长及其与化肥混施的增效机制研究进展

利用秸秆型生物炭进行还田改土不仅具有提升作物产量的潜力,而且能够产生明显的环境效益,现已成为当今国内外农业领域的研究热点.本文综述了近年来国内外有关生物炭添加影响作物生长的分子调控机制研究,尤其关注了生物炭与作物根系的互作效应;介绍了生物炭与化肥混施的生物学效应及可能的增效机制;展望了今后的研究方向,以期促进我国相关领域的研究.国内外的最新研究表明:生物炭土壤添加改善植物生长的关键是生长素相关信号转导分子,通过促进植物细胞扩增、细胞壁松弛、水及营养的转运等相关基因的表达,有利于植物的新陈代谢及生长.生物炭及其与根系的相互作用能够直接或间接地影响土壤物理、化学、生物因子,从而在炭、肥互作增效过程中起主导调控作用.     

Biochar – synergies and trade‐offs between soil enhancing properties and C sequestration potential

The characterization of biochar has been predominantly focused around determining physicochemical properties including chemical composition, porosity and volatile content. To date, little systematic research has been done into assessing the properties of biochar that directly relate to its function in soil and how production conditions could impact these. The aim of this study was to evaluate how pyrolysis conditions can influence biochar's potential for soil enhancing benefits by addressing key soil constraints, and identify potential synergies and restrictions. To do this, biochar produced from pine wood chips (PC), wheat straw (WS) and wheat straw pellets (WSP) at four highest treatment temperatures (HTT) (350, 450, 550 and 650 °C) and two heating rates (5 and 100 °C min^?1) were analysed for pH, extractable nutrients, cation exchange capacity (CEC), stable‐C content and labile‐C content. Highest treatment temperature and feedstock selection played an important role in the development of biochar functional properties while overall heating rate (in the range investigated) was found to have no significant effect on pH, stable‐C or labile‐C concentrations. Increasing the HTT reduced biochar yield and labile‐C content while increasing the yield of stable‐C present within biochar. Biochar produced at higher HTT also demonstrated a higher degree of alkalinity improving biochar's ability to increase soil pH. The concentration of extractable nutrients was mainly affected by feedstock selection while the biochar CEC was influenced by HTT, generally reaching its highest values between 450–550 °C. Biochar produced at ≥550 °C showed high combined values for C stability, pH and CEC while lower HTTs favoured nutrient availability. Therefore attempts to maximize biochar's C sequestration potential could reduce the availability of biochar nutrients. Developing our understanding of how feedstock selection and processing conditions influence key biochar properties can be used to refine the pyrolysis process and design of ‘bespoke biochar’ engineered to deliver specific environmental functions.     

Cost-benefit analysis of using biochar to improve cereals agriculture

Biochar has received considerable scientific attention in the past decade as a possible method for carbon storage and increasing agricultural yields. Despite this promise, however, economic assessments of biochar are yet to definitively establish the value of the technology, primarily due to discrepancy between observed short-term agronomic benefits and expectations of biochar as a lasting soil improver. This study investigated the economic value of biochar as an agricultural technology for long-term improvement of arable farming. From presently available field trial data, the costs and benefits of using biochar technology to enhance cereals agriculture were evaluated in two generalized geo-economic agricultural scenarios: North-Western Europe (NWE) and Sub-Saharan Africa (SSA). Cost models were developed to estimate the total cost of biochar from initial biomass feedstock acquisition to final soil application for each agricultural setting. Benefits of biochar application were estimated by statistical meta-analysis of crop yield data from published biochar field trials to find the increase in cereal grain yield attributable to biochar application for both NWE (+0.07 to +0.28 t ha⁻¹ yr⁻¹) and SSA (+0.18 to +1.00 t ha⁻¹ yr⁻¹). The grain yield improvement from a one-time biochar application was assumed to persist without decay for an independently varying time period, and the increase in grain production then monetised using projected future commodity prices. The Net Present Value (NPV) of applying biochar was then calculated by setting present total costs against present total benefits as a function of biochar performance longevity. Biochar application was found to carry a positive NPV for cereal cropping in SSA in several scenarios where the duration of the biochar yield effect was assumed to extend 30 years into the future. Conversely, NWE biochar scenarios were all found to have negative NPVs even when the benefits time span was indefinitely stretched.     

Efforts for a Circular Economy in China: A Comprehensive Review of Policies

Circular economy concepts, practices, and policies are increasingly drawing attention as important means for the pursuit of sustainable development. This article uses a conceptual framework to catalogue and investigate policy efforts for the circular economy in China. Based on the framework, policy prototypes and specific examples are identified: resource‐oriented, production‐oriented, waste, and use‐oriented and life cycle policies. A comprehensive review of 280 related policies shows that China has a long history of resource‐oriented policies and implemented production‐oriented policies very quickly after the year 2000. China's policies toward the circular economy became more comprehensive through time, with a broad engagement of government agencies, an extensive and progressive coverage of recycling opportunities, production initiatives across multiple scales, and use of different policy instruments. The continuous progress has been driven by proactive state actors and their learning from the international society. The current policy framework, however, is concerned more with the means rather than the ends of the circular economy, and relies too much on direct subsidies and other financial incentives. Policy making can be improved by more explicit consideration of the whole production life cycle and use of market‐based policy design.     

Life-cycle based government policies a survey

This paper examines how different Life-Cycle Assessment (LCA) approaches, from full LCA’s to more qualitative LCA’s, are being used internationally in the development of government policies. Examples from 14 countries are provided for recent initiatives in various forms of policy which were developed to move national environmental policies toward the more life-cycle based programs. They indicate that a broader frame of reference is beginning to be used by those who write such policies. Discussion is also provided on the barriers that slow the adoption of life-cycle approaches in the development of government policies.     

Biochar Production and Application in Forest Soils-A Critical Review

The increasing deforestation with an alarming rate is the prime cause of upsetting the balance in the natural ecosystem and the livelihood of local communities. Sustainable forest management and reforestation efforts can equilibrium this destruction and maintain the protected areas. In this regard, soil management strategies for reforestation of the degraded forest land can be helpful. In this review, the potential of using biochar, a solid carbon rich product of biomass thermochemical conversion, as a soil amendment in forest soils has been discussed. The production procedures of biochar, availability of feedstocks and the biochar properties are discussed using the existing knowledge. The positive effects of biochar are soil quality depended and change with varying geographical locations. Therefore, long-term field trials examining a range of biochars, soils, and forest types are required for a better understanding of this issue. Careful planning to match biochar with the soil properties is essential to obtain maximum benefits of biochar as a soil amendment.     

Adoption of Policy Incentives and Land Use: Lessons From Frontier Agriculture in Southeastern Peru

Literature on environmental change often highlights the importance of public policies as a key driver of land use and land cover change. However, demonstration of policy impacts in agricultural settings has been hampered by the lack of systematic analysis across landholders, who may not universally adopt government policy incentives, or time periods, which may be associated with differing policy regimes. This paper evaluates the importance of voluntary adoption of policy incentives offered by Peruvian government administrations over two decades for land-use among small farmers in the Peruvian Amazon. The analysis focuses on whether farmers adopted one or more policy incentives in order to observe the effects on land uses including mature forest, agricultural crops, cattle pasture, and secondary growth. We employ multivariate statistical models to estimate the effects of policy adoption while controlling for other factors. The findings show that distinct policies are associated with particular land-uses and largely follow expectations. Specifying policy incentives promulgated by governments and differentiating among adopters and non-adopters advances understanding of the impacts of public policies on land use.     

Biochar supply-chain and challenges to commercialization

Produced through pyrolysis, biochars are used as a soil amendment. Differences in feedstock and processing result in differentiated products which impact their values in different soil conditions. Despite the enormous potential, biochars have not been widely used. This paper overviews the benefits and potential demand for biochar and features of supply chain, and identifies opportunities for viable introduction of biochars. The value of biochars should be evaluated as a part of the pyrolysis system that coproduces biochars and biofuels. Biochars can improve agricultural productivity and soil functioning and contribute to climate change mitigation through carbon sequestration. Furthermore, it can provide extra benefit by contributing to fire prevention. The cost of biochar system depends on the costs of feedstock acquisition, transportation, and processing. Biochar is most likely to be adopted in locations with marginal land and high-value crop, and near low-cost feedstock sources. The adoption of biochar can be enhanced by compensation for carbon sequestration, further investment in research, and learning of producers to enhance efficiency of the supply chain.     

Perennial biomass cropping and use: Shaping the policy ecosystem in European countries

Demand for sustainably produced biomass is expected to increase with the need to provide renewable commodities, improve resource security and reduce greenhouse gas emissions in line with COP26 commitments. Studies have demonstrated additional environmental benefits of using perennial biomass crops (PBCs), when produced appropriately, as a feedstock for the growing bioeconomy, including utilisation for bioenergy (with or without carbon capture and storage). PBCs can potentially contribute to Common Agricultural Policy (CAP) (2023–27) objectives provided they are carefully integrated into farming systems and landscapes. Despite significant research and development (R&D) investment over decades in herbaceous and coppiced woody PBCs, deployment has largely stagnated due to social, economic and policy uncertainties. This paper identifies the challenges in creating policies that are acceptable to all actors. Development will need to be informed by measurement, reporting and verification (MRV) of greenhouse gas emissions reductions and other environmental, economic and social metrics. It discusses interlinked issues that must be considered in the expansion of PBC production: (i) available land; (ii) yield potential; (iii) integration into farming systems; (iv) R&D requirements; (v) utilisation options; and (vi) market systems and the socio-economic environment. It makes policy recommendations that would enable greater PBC deployment: (1) incentivise farmers and land managers through specific policy measures, including carbon pricing, to allocate their less productive and less profitable land for uses which deliver demonstrable greenhouse gas reductions; (2) enable greenhouse gas mitigation markets to develop and offer secure contracts for commercial developers of verifiable low-carbon bioenergy and bioproducts; (3) support innovation in biomass utilisation value chains; and (4) continue long-term, strategic R&D and education for positive environmental, economic and social sustainability impacts.     

The Chilean Espinal: Restoration for a Sustainable Silvopastoral System

The mediterranean habitats of central Chile are rich in endemic species, but threatened by land‐use changes. In this context, we suggest that restoration of the traditional espinal silvopastoral system could improve its sustainability and conservation value. Past research on the espinal embraced negative stereotypes of peasants, the tree Acacia caven, and the semiarid landscape to recommend abandoning the silvopastoral system. We think that recommendation is premature and ignores the value of the espinal as a classical Chilean cultural landscape. Drawing on lessons from silvopastoral systems in Latin America and the Mediterranean, here we suggest several management interventions and incentives that could be developed to restore the espinal. Particular challenges in espinal include low biomass production due to the semiarid climate and the lack of a traditional sustainable timber or non‐timber product of A. caven. Our recommendations include sustainable production and use of biochar and bark extracts from A. caven to improve espinal soils, the promotion of shrubs and the use of small mammal disturbances, and their artificial analogs to improve A. caven reproduction, and rotational livestock herding to form mosaic landscapes. These techniques could lead to higher forage biomass and increased livestock weights. Incentive structures to implement these management activities could include tax benefits for private protected area (IUCN category VI) creation, REDD+ and PES programs, along with promotion of the cultural value of the espinal. Further research is urgently called for on ecosystem services, ecological baselines, biochar, and other management and incentive structures that could be applied in the espinal.     

Incentives for biodefense countermeasure development

Therapeutics and vaccines are available for only a fraction of biological threats, leaving populations vulnerable to attacks involving biological weapons. Existing U.S. policies to accelerate commercial development of biodefense products have thus far induced insufficient investment by the biopharmaceutical industry. In this article, we examine the technical, regulatory, and market risks associated with countermeasure development and review existing and proposed federal incentives to increase industrial investment. We conclude with several recommendations. To increase industry's engagement in biodefense countermeasure development, Congress should expand BioShield funding, giving HHS the flexibility to fund a portfolio of biodefense countermeasures whose revenues are comparable to those of commercial drugs. Congress should establish tradable priority review vouchers for developers of new countermeasures. A National Academy of Sciences or National Biodefense Science Board should formally evaluate incentive programs and a government-managed "Virtual Pharma," in which HHS contracts separate stages of research, development, and production to individual firms.     

Pyrogenic carbon capture and storage

The growth of biomass is considered the most efficient method currently available to extract carbon dioxide from the atmosphere. However, biomass carbon is easily degraded by microorganisms releasing it in the form of greenhouse gases back to the atmosphere. If biomass is pyrolyzed, the organic carbon is converted into solid (biochar), liquid (bio‐oil), and gaseous (permanent pyrogas) carbonaceous products. During the last decade, biochar has been discussed as a promising option to improve soil fertility and sequester carbon, although the carbon efficiency of the thermal conversion of biomass into biochar is in the range of 30%–50% only. So far, the liquid and gaseous pyrolysis products were mainly considered for combustion, though they can equally be processed into recalcitrant forms suitable for carbon sequestration. In this review, we show that pyrolytic carbon capture and storage (PyCCS) can aspire for carbon sequestration efficiencies of >70%, which is shown to be an important threshold to allow PyCCS to become a relevant negative emission technology. Prolonged residence times of pyrogenic carbon can be generated (a) within the terrestrial biosphere including the agricultural use of biochar; (b) within advanced bio‐based materials as long as they are not oxidized (biochar, bio‐oil); and (c) within suitable geological deposits (bio‐oil and CO₂ from permanent pyrogas oxidation). While pathway (c) would need major carbon taxes or similar governmental incentives to become a realistic option, pathways (a) and (b) create added economic value and could at least partly be implemented without other financial incentives. Pyrolysis technology is already well established, biochar sequestration and bio‐oil sequestration in soils, respectively biomaterials, do not present ecological hazards, and global scale‐up appears feasible within a time frame of 10–30 years. Thus, PyCCS could evolve into a decisive tool for global carbon governance, serving climate change mitigation and the sustainable development goals simultaneously.     

生物炭对菜园土壤微生物功能多样性的影响

研究生物炭的施用及其与不同肥料混施对菜园土壤中微生物群落功能多样性的影响,为农业废弃物的合理利用和菜园土优化培肥提供科学依据和理论指导。以清远市连州县代表性菜园土(属肥熟旱耕人为土)为研究对象,通过盆栽试验,利用BIOLOG方法对10个施肥处理(对照CK(0%生物碳+无肥)、T1(0%生物碳+0.1%商品有机肥)、T2(0.1%生物碳+无肥)、T3(0.25%生物碳+无肥)、T4(0.5%生物碳+无肥)、T5(1%生物碳+无肥)、T6(100(N)+30(P_2O_5)+75(K_2O)mg/kg干土)、T7(0.1%生物碳+0.1%商品有机肥)、T8(0.1%生物碳+100(N)+0(P_2O_5)+75(K_2O)mg/kg干土)、T9(0.1%生物碳+100(N)+30(P_2O_5)+75(K_2O)mg/kg干土)、T10(0.1%生物碳+0.1%商品有机肥+100(N)+0(P_2O_5)+75(K_2O)mg/kg干土))的土壤微生物群落功能多样性进行分析。结果表明:(1)T1和T3处理比其它处理显著提高土壤微生物对碳源的利用率(P0.05),但生物炭施用量增加会降低平均颜色变化率(AWCD值);(2)T1处理可以显著提高土壤微生物的群落物种均匀度(Mclntosh指数),而T3处理显著提高土壤微生物的物种丰富度和均匀度(Shannon和Mclntosh指数);(3)T1和T3处理对聚合物类、碳水化合物类、羧酸类、氨基酸类和酚类碳源利用率最高;(4)添加化肥处理中磷肥的施用可以提高土壤微生物活性,增加土壤微生物碳源利用能力,而氮肥和钾肥的添加显著降低了土壤微生物的碳源利用能力;(5)主成分分析表明,T1、T2和T3处理的微生物碳代谢功能群结构相似;单施有机肥或适量生物炭对土壤微生物群落结构的影响较混合施用更为显著;化学磷肥的添加及在施用化肥的基础上配施适量生物炭改变了土壤微生物对碳源种类的利用。     

An appraisal of the utility of biochar in a rotation involving tobacco–rice in southern China

The employment of biochar in crop production can not only improve soil quality, but also helps the field ecosystem to fix carbon and reduce emissions. Although the benefits of their application in crop production have been more and more confirmed, it is not clear when it comes to the acidic soil of tobacco and rice rotation. A tobacco–rice rotation experiment was conducted in southern China to probe the application value of biochar under these conditions. Three biochar application rates were employed in this experiment. BC0 (without biochar), BC25 (25 t ha⁻¹), and BC50 (50 t ha⁻¹). The findings show that biochar significantly boosted soil fertility and crop yields. Meanwhile, the soil organic carbon of tobacco rice rotation field with biochar increased by 31.76%. After a whole growth period of tobacco and rice, the cumulative emission reduction of CO₂ and N₂O from the soil by biochar were 15,944 kg ha⁻¹ and 1810 g ha⁻¹, respectively. The use of biochar not only significantly improved the bacterial diversity of tobacco and rice rotation soil, but also altered the original microbial community structure. The profusion of Proteobacteria and Acidobacteria was reduced and the abundance of Actinobacteria and Bacteroidetes was enhanced in the treatments with biochar. Among them, Sphingomonadales, Planctomycotes, and Ktedonobacteria, which are beneficial to plant growth and soil health, have become key phylotypes. The carbon balance analysis data show that the net carbon sequestration of the two treatments with biochar is positive, while that of the treatment without biochar is negative. In terms of economic benefit, the application of biochar increased the average of 2.055 CNY kg⁻¹ consumed energy (CE) in the whole tobacco–rice rotation system. The ecological benefit was 0.51 kg C kg⁻¹ CE. In conclusion, biochar can be effectively used in the practice of tobacco–rice rotation and acidic soil improvement in southern China.     

The ethics of biofuels

The rapid development and adoption of biofuels has been driven by a wide range of targets and other policy instruments, but first‐generation biofuels have been widely criticized. In light of the development of new biofuel technologies that aim to avoid the problems of the past, the Nuffield Council on Bioethics conducted an 18‐month inquiry on the ethical, social and policy issues raised by both current and future biofuels. The Council concludes that many biofuels policies fail to take consideration of important ethical principles, such as protecting human rights, environmental sustainability, climate change mitigation, just reward, and equitable distribution of costs and benefits. It proposes an overarching ethical standard for biofuels, enforced by a certification scheme for all biofuels produced in and imported into Europe and ideally worldwide.     

The effect of consumption and production policies on circular economy business models: A machine learning approach

The circular economy (CE) is attracting increasing interest, as it can bring environmental, social, and economic benefits. However, policymakers and scholars appear to concentrate more on the production side of CE, while consumption, and particularly policies that affect consumption have received less attention and their effect is ambiguous. This paper investigates the effect of CE consumption policies on circular economy business models (CEBMs) in firms, but also examines the interplay this type of policies have with CE production policies to have a broader picture of the circular economy policy framework and the relevance of each type of policy on firms. While previous studies assume rational and passive consumer behavior, this paper borrows from a natural resource-based view and stakeholder theory, arguing that consumers have a proactive attitude toward the consumption of environmentally friendly products. Moreover, we use institutional theory as an analytical framework for modeling the effects of a particular policy framework on the CEBM. Our analysis combines classical econometric methods with machine learning approaches, employing data from the EU. The results show that CE policies aimed at promoting consumption have a direct and positive effect on CEBMs. This paper also confirms that a wide portfolio of CE policies on production and consumption has a greater effect on the development of CEBMs, due to the complementarity of CE consumption and production policies. Moreover, we show that in interaction with CE production policies, CE policies on consumption have an even greater effect on CEBMs in firms than would have been anticipated.     

生物质炭生物与非生物氧化特性研究进展

生物质炭是由植物生物质热解炭化产生的一类高度芳香化难熔性固态物质。生物质热解炭化还田能否成为人类应对全球气候变化的重要途径直接取决于其在土壤生态系统中的稳定性。生物质炭稳定性的研究对科学计算和评估土壤生态系统生物质炭输入的碳固持与减排作用具有重要现实意义。重点概述了土壤生态系统生物质炭生物与非生物氧化特性、影响因素及其机理研究进展,并对生物质炭在土壤环境中的稳定性预测模型研究进行了分析。在此基础上,今后需针对不同类型旱地土壤生态系统和不同类型稻田土壤生态系统生物质炭稳定性及其机理开展研究,并进一步开展土壤生态系统生物质炭稳定性预测模型研究。     

‘Bioenergy from cattle manure? Implications of anaerobic digestion and subsequent pyrolysis for carbon and nitrogen dynamics in soil’

Cattle manure can be processed to produce bioenergy, resulting in by‐products with different physicochemical characteristics. To evaluate whether application of such bioenergy by‐products to soils would be beneficial compared with their unprocessed counterpart, we quantified differences in greenhouse gas emissions and carbon (C) and nitrogen (N) dynamics in soil. Three by‐products (¹⁵N‐labeled cattle manure, from which anaerobic digestate was obtained, which was subsequently pyrolysed) were applied to a loess and a sandy soil in a laboratory incubation study. The highest losses of soil C from biological activity (CO₂ respiration) were observed in manure treatments (39% and 32% for loess and sandy soil), followed by digestate (31% and and 18%), and biochar (15% and and 7%). Emissions of nitrous oxide (N₂O) ranged from 0.6% of applied N from biochar to 4.0% from manure. Isotope labeling indicated that manure N was most readily mineralized, contributing 50% to soil inorganic N. The anaerobic digestate was the only by‐product increasing the mineral N pool, while reducing emissions of N₂O compared with manure. In biochar treatments, less than 18.3% of soil mineral N derived from the biochar, while it did not constrain mineralization of native soil N. By‐products of anaerobic digestion and pyrolysis revealed soil fertility in addition to environmental benefits. However, the reported advantages lessen when the declining yields of C and N over the bioenergy chain are considered.