Enhancing Cation Exchange Capacity of Weathered Soils Using Biochar: Feedstock, Pyrolysis Conditions and Addition Rate

The addition of alkaline and high-cation exchange capacity (CEC) biochars is a suitable strategy to increase the CEC of weathered soils. The aim of this study was to evaluate the effect of biochar from different feedstocks and pyrolysis temperatures on the CEC of two contrasting Oxisols. Biochars produced from chicken manure (CM), eucalyptus sawdust (ES), coffee husk (CH) and sugarcane bagasse (SB),plus a control (without biochar), at 350, 450, and 750 °C were mixed with the soils at 2; 5; 10 and 20% (w/w) and incubated for 9 months. Feedstock, pyrolysis temperature and addition rate of biochar were key factors controlling the alteration of soil CEC. The CH biochar pyrolyzed at 350 °C was the most effective matrix at increasing soil CEC. In a rate-dependent way, ES and SB biochars increased C contents of both soils without improving soil CEC. The efficiency of high-ash biochars in enhancing soil CEC in both Oxisols was limited by the alkalization caused by high rates of CH and CM biochars. The increase in CEC is soil-dependent and modulated by high-ash biochar CEC and application rate, as well as by the original soil CECThis study was funded by the National Council for Technological and Scientific Development—CNPq, grants 303899/2015-8 and 307447/2019-7, and the Coordination for the Improvement of Higher Level Education Personnel (CAPES-PROEX AUXPE 593/2018). CAPES provided a PhD scholarship for RRD, and CNPq financed researchscholarshipsforPFT,LCAMandCAS.MASMwouldliketoacknowledgeProjectNo. RTI2018-099417-B-I00 from the Spanish Ministry of Science, Innovation and Universities, cofinanced with EU FEDER fundsPeer reviewe

Influence of pyrolysis temperature on cadmium and zinc sorption capacity of sugar cane straw-derived biochar

The effect of pyrolysis temperature on the characteristics and metal sorption capacity of sugar cane straw derived–biochar (BC) was investigated. Biochar was produced at four temperatures (400, 500, 600, and 700 °C) before characterization for yield, ash and moisture content, pH, EC, pH PZC , elemental composition, nutrient content, CEC, TGA, and functional groups (FT-IR). Biochar alone and in mixtures containing 10%, w/w biochar with one of two different tropical soils (Entisol and Oxisol) was shaken for 24 h with a 2.0 mM solution (pH 4.5) of Zn or Cd in a batch sorption test. Increasing the pyrolysis temperature led to a reduction in the O/C and H/C molar ratios. The sorption capacity of biochar pyrolyzed at 700 °C was nearly four times greater than that produced at 400 °C. In the Entisol mixture, there was an increase up to seven-fold in the sorption of both Cd and Zn compared with the control (without BC). In the Oxisol mixture, there was a maximum 20% increase in sorption compared with the control. For the remediation of Cd- and Zn- contaminated substrates, the use of higher pyrolysis temperature biochars are recommended because of their higher metal sorption capacities

Distribuição espacial de fósforo em Latossolo tratado com lodo de esgoto e adubação mineral

Em solos agrícolas que recebem aplicação de lodo de esgoto pode ocorrer, quando sujeitos à erosão hídrica, intenso transporte de fósforo (P) para trechos inferiores da paisagem e, eventualmente, para os corpos de água. O objetivo com este trabalho foi avaliar a distribuição espacial de P em um Latossolo Vermelho eutroférrico, cultivado com milho. Os tratamentos foram avaliados com aplicação de adubo mineral (AM) e de lodo de esgoto (LE). Amostras de solo foram coletadas seguindo uma grade amostral de 69 pontos em cada tratamento, em duas épocas, no início e no final do ciclo da cultura, em uma área experimental com 10% de declividade. No tratamento AM houve dependência espacial moderada de P no solo ocorrendo maiores concentrações de P na parte inferior do talhão, causada pela erosão do solo. O mesmo padrão foi observado para soma de bases, capacidade de troca catiônica e matéria orgânica do solo. Por outro lado, a aplicação de LE, feita de maneira não uniforme, resulta em sítios com maiores teores de fósforo aleatoriamente distribuídos e correlacionados com a matéria orgânica do solo

Properties of biochar derived from wood and high-nutrient biomasses with the aim of agronomic and environmental benefits

<div><p>Biochar production and use are part of the modern agenda to recycle wastes, and to retain nutrients, pollutants, and heavy metals in the soil and to offset some greenhouse gas emissions. Biochars from wood (eucalyptus sawdust, pine bark), sugarcane bagasse, and substances rich in nutrients (coffee husk, chicken manure) produced at 350, 450 and 750°C were characterized to identify agronomic and environmental benefits, which may enhance soil quality. Biochars derived from wood and sugarcane have greater potential for improving C storage in tropical soils due to a higher aromatic character, high C concentration, low H/C ratio, and FTIR spectra features as compared to nutrient-rich biochars. The high ash content associated with alkaline chemical species such as KHCO₃ and CaCO₃, verified by XRD analysis, made chicken manure and coffee husk biochars potential liming agents for remediating acidic soils. High Ca and K contents in chicken manure and coffee husk biomass can significantly replace conventional sources of K (mostly imported in Brazil) and Ca, suggesting a high agronomic value for these biochars. High-ash biochars, such as chicken manure and coffee husk, produced at low-temperatures (350 and 450°C) exhibited high CEC values, which can be considered as a potential applicable material to increase nutrient retention in soil. Therefore, the agronomic value of the biochars in this study is predominantly regulated by the nutrient richness of the biomass, but an increase in pyrolysis temperature to 750°C can strongly decrease the adsorptive capacities of chicken manure and coffee husk biochars. A diagram of the agronomic potential and environmental benefits is presented, along with some guidelines to relate biochar properties with potential agronomic and environmental uses. Based on biochar properties, research needs are identified and directions for future trials are delineated.</p></div

Values of pH-H₂0 (A), liming value (B), EC—electrical conductivity (C), and CEC—cation exchange capacity (D) as related to biomass and biochars.

<p>CM = chicken manure, ES = eucalyptus sawdust, CH = coffee husk, SB = sugarcane bagasse, and PB = pine bark. Uppercase letters compare pyrolysis temperatures within the same biomass and lowercase letters compare biomass at the same temperature. Bar followed by the same letter do not differ by the Tukey test at <i>p</i> <0.05.</p

Simplified schematic representation in which wood, sugarcane, coffee husk, and chicken manure biochars are typified according to chemical and physiochemical properties and potential for carrying out trials on weathered soils in regard to their potential agronomic or environmental services.

<p>Simplified schematic representation in which wood, sugarcane, coffee husk, and chicken manure biochars are typified according to chemical and physiochemical properties and potential for carrying out trials on weathered soils in regard to their potential agronomic or environmental services.</p

Yield and proximate analysis (volatile matter, ash, carbon fixed) of biochars produced at different pyrolysis temperatures.

<p>Yield and proximate analysis (volatile matter, ash, carbon fixed) of biochars produced at different pyrolysis temperatures.</p