ABSTRACT. Biochar is a carbon-rich material produced during organic waste pyrolysis. In this context, two experiments were performed to evaluate the effect of biochar produced from rice husks and cattle manure on soil fertility and common bean production, as well as to identify the optimal dose of cattle manure biochar to be applied. The first experiment (Experiment I) was conducted according to a completely randomized design (factorial scheme 2 × 2 × 2 + 1) with six replicates: two types of biochar (cattle manure biochar and rice husk biochar), with and without acidity correction [addition of calcium carbonate and magnesium carbonate (PA) in a proportion of 4:1 (Ca:Mg) to raise the soil base saturation to 60%], with or without the addition of 120 mg dm-3 of phosphorus (P) as ammonium phosphate, and a control treatment (without biochar, acidity correction, and P). Based on the results of Experiment I, a second experiment was conducted according to a completely randomized design, with five treatments (doses of biochar from cattle manure) and four replications. Rice husk biochar, as a conditioner of soil chemical properties, had less prominent effects than cattle manure biochar. Cattle manure biochar functioned as a corrective for soil acidity and a source of nutrients (mainly phosphorus). The dose corresponding to 5.46% of the soil volume led to the maximum grain production by common bean plants.

ABSTRACT: This study evaluated the levels of heavy metals in the soil and castor bean plant after fertilization with sewage sludge (SS) subjected to different stabilization processes. The study was conducted in a Haplic Cambisol with the following treatments: control (CO), fertilization with solarized sewage sludge (SSS), composted sewage sludge (CSS), vermi composted sewage sludge (VSS), limed sewage sludge (LSS), and mineral fertilizer (MF). The experimental design included a subdivided plot scheme with fertilization being the primary factor and soil layers or leaf parts being the secondary factor. The data obtained were analyzed using analysis of variance and the Scott-Knott test with 5% significance. Fertilization with SSS, CSS, and LSS led to the highest increase in Zn in the soil, mainly in the surface layer. In the leaf tissues, Zn and Cu levels were higher with the CO and SSS treatments, whereas the Ni level was higher with SSS, CSS, VSS, and MF treatments. In general, Zn and Cu levels were higher in the leaf limb than in the petiole, whereas Ni, Pb, and Cr levels were higher in the petiole than in the leaf limb. In any case, no symptoms of toxicity in the plants and no risk of soil contamination were observed with any of the fertilization treatments.

RESUMO: O objetivo deste trabalho foi avaliar os teores de metais pesados no solo e na planta de mamoneira em resposta à adubação com lodo de esgoto (LE) submetido a diferentes processos de estabilização. O experimento foi desenvolvido em Cambissolo Háplico com os tratamentos: testemunha, adubação com LE solarizado, LE compostado, LE vermicompostado, LE caleado e adubação mineral. O delineamento experimental foi em esquema de parcelas subdivididas, sendo as adubações o fator primário e as camadas do solo ou as partes da folha o fator secundário. Os dados obtidos foram submetidos à análise de variância e teste de Scott-Knott a 5% de probabilidade. No solo, as adubações com LE solarizado, compostado e caleado promoveram os maiores incrementos dos teores de Zn, principalmente na camada superficial. No tecido foliar, os teores de Zn e Cu foram mais elevados na testemunha e no LE solarizado, enquanto o Ni foi mais elevado nos LE solarizado, compostado, vermicompostado e na adubação mineral. De modo geral, os maiores teores de Zn e Cu ocorreram no limbo foliar em comparação ao pecíolo, enquanto os teores de Ni, Pb e Cr foram mais elevados no pecíolo do que no limbo foliar. Contudo, não foram constatados sintomas de toxidez nas plantas e nenhum risco de contaminação do solo com os diferentes tipos de adubações realizadas.

RESUMO O cultivo de gramíneas em lodo de esgoto com aeração melhora a qualidade desse fertilizante, uma vez que o crescimento das raízes, a liberação de exsudatos e a oxigenação favorecem a mineralização dos nutrientes e a humificação da matéria orgânica. Assim, o presente trabalho teve como objetivo avaliar a decomposição de lodo de esgoto utilizando-se cultivo com gramínea e aeração para uso como adubo orgânico. O experimento foi realizado no delineamento em blocos casualizados com quatro repetições, num esquema fatorial 2 x 5, correspondendo à presença ou não de cultivo com Pennisetum purpureum em lodo de esgoto, combinado com cinco períodos de aeração: 0, 14, 28, 42 e 60 dias, com vazão de ar de 1.059 dm3.h−1.kg−1 de sólidos voláteis. As análises mostraram que a injeção de ar no lodo de esgoto não influenciou a decomposição da matéria orgânica e a realização de cultivo da gramínea em lodo de esgoto aumentou os teores de N, Ca, S, Na e resíduos minerais solúveis, bem como a condutividade elétrica, indicando sua mineralização. Em contrapartida, o cultivo diminuiu os teores totais de Fe e Pb, propiciando redução no risco de toxidez desses elementos. Para aplicação em solos agrícolas e áreas degradadas, o lodo de esgoto enquadra-se como da classe 2, atendendo completamente à norma vigente. Pelos baixos valores de C orgânico do lodo utilizado, a biomassa vegetal produzida pode ser incorporada ao lodo de esgoto para adequação e registro como fertilizante orgânico.

ABSTRACT The cultivation of grasses in sewage sludge (SS) with aeration improves the quality of this fertilizer, since the growth of the roots, the release of exudates and oxygenation, favor the mineralization of nutrients and the humification of organic matter. Thus, the present work aimed to evaluate the decomposition of SS using grass cultivation and aeration for use as organic fertilizer. The experiment was carried out in a randomized block design with four replications, in a 2 x 5 factorial scheme, corresponding to the presence or absence of culture with Pennisetum purpureum in SS, combined with five periods of aeration: 0, 14, 28, 42, and 60 days, with an air flow of 1,059 dm3.h−1.kg−1 of volatile solids. The analyses showed that the air injection in the SS did not influence the decomposition of organic matter and the cultivation of the grass in SS increased the levels of N, Ca, S, Na and soluble mineral residues, as well as the electrical conductivity, indicating its mineralization. On the other hand, cultivation decreased the total levels of Fe and Pb, providing a reduction in the risk of toxicity of these elements. For application in agricultural soils and degraded areas, the sewage sludge is classified as Class 2, completely complying with the current regulation. Due to the low organic C values of the sludge used, the vegetable biomass produced can be incorporated into it for suitability and registration as organic fertilizer.

RESUMO: Nos últimos anos, tem aumentado o interesse crescente pelo uso de resíduos orgânicos na agricultura. Dessa forma, objetivou-se com este estudo avaliar o biochar e a casca do pequi (Caryocar brasiliense Cambess) nas propriedades químicas do solo e na produção e nutrição de plantas de feijoeiro. O experimento foi realizado em vasos com solo (4 dm3 ~ 5,44 kg), em delineamento experimental inteiramente casualizado, em esquema fatorial 4 x 3 + 2, com quatro repetições. Os tratamentos foram quatro doses de biochar (0,0, 2,5, 5,0, 7,5 e 10,0 % v/v), três tamanhos de partículas diferentes (G1, <0,5 mm; G2, 0,5-1,0 mm e G3, 1,0-2,0 mm) e dois tratamentos controle, um sem e outro com adição de corretivo da acidez do solo. O biochar de casca do pequi atuou como corretivo da acidez do solo e como fonte de potássio para as plantas. Entretanto, em doses mais elevadas de biochar, houve uma diminuição na produção das plantas de feijão devido aos desequilíbrios nutricionais.

ABSTRACT: In recent years there has been a growing interest in the use of organic waste in agriculture. In this way, was aimed with this study to evaluate the biochar from pequi shell (Caryocar brasiliense Cambess) on the soil chemical properties and on the production and nutrition of common bean plants. The experiment was carried out in pots with soil (4 dm3 ~ 5,44 kg), in a completely randomized experimental design, 4 x 3 + 2 factorial scheme, with four replications. The treatments were four doses of biochar (0.0, 2.5, 5.0, 7.5 and 10.0 % v/v), three different particle size (G1, <0.5 mm; G2, 0.5-1,0 mm and G3, 1.0-2.0 mm) and two control treatments, one without and another with addition of soil corrective acidity. The biochar from pequi shell acted as a corrective of soil acidity and as a source of potassium for the plants. However, in higher doses of biochar there was a decrease in bean plants production due to nutritional imbalances.

ABSTRACT The cultivation of grasses in sewage sludge (SS) with aeration has the potential for stabilization of sludge organic matter in the production of organic fertilizer. Thus, the objective of this work was to evaluate the cultivation of Urochloa brizantha and Pennisetum purpureum under aerated system on the chemical and biological attributes of SS to obtain a matured organic fertilizer. The study was conducted in a randomized block design in a 2x2+2 factorial scheme with four replications. Factors consisted of cultivation of P. purpureum or U. brizantha in SS, with or without intermittent aeration. Control treatments were SS without cultivation, with or without aeration. Sewage sludge was collected in layers and the chemical and microbial attributes were evaluated. There was no significant difference between treatments for grass dry matter. The C/N ratio was not matched with organic fertilizer stabilization due to similar losses of C and N (~7%). However, microbial activity was reduced in the presence of plant cultivation demonstrating improvement in the properties of the organic fertilizer produced. Through uni- and multivariate analysis, organic fertilizer produced from SS aerated and cultivated with P. purpureum showed matured organic matter.

ABSTRACT The use of residues for agricultural production is an alternative for the achievement of sustainability. When mixed with diatomaceous earth (DE) from biofuel filtration, sewage sludge (SS) plays an important role as soil conditioning agent. As a result, the objective of this work was to make a DE vermicompost at different proportions: 0; 7.53; 15.06; 22.59 and 30.12% v/v in relation to a SS pre-compost (PC) and gardening pruning residues. The experiment was carried out in 100-L containers in a randomized block design, with 5 treatments and 5 replications, in which Eisenia foetida earthworms were used in the pre-composting and vermicomposting processes. After four months, the physical characteristics of the vermicompost were analyzed. It was verified that the diatomaceous earth can be vermicomposted, even when soaked in biofuel oil, at amounts of up to 30.12% v/v, with no visible physical damage to earthworms and plants, and this proportion of DE reduced the concentration of nutrients, but improved the physical properties of the vermicompost, making it an excellent physical conditioner for use as a substrate of plants and fertilization of soils.

RESUMO Estudos relacionados à adubação nitrogenada e fixação biológica de nitrogênio no aumento da produção de grão-de-bico são considerados escassos em regiões tropicais. Objetivou-se avaliar a inoculação do Rhizobium tropici e doses de N sob condições irrigadas em região tropical nos componentes de produção e desenvolvimento do grão-de-bico, em solos com maior e menor teor de matéria orgânica (MOS). O delineamento foi em blocos ao acaso, com quatro repetições, esquema fatorial 2 x 6, consistindo da presença e ausência da inoculação do R. tropici e seis doses de 0, 25, 50, 75, 100 e 125 kg ha-1 de N na forma de ureia. O estudo foi dividido em duas áreas com distintos teores de matéria orgânica do solo (MOS). Na área com menor teor de MOS (3.55 dag kg-1), a inoculação com R. tropici ou a adubação com 125 kg ha-1 de N aumentaram os teores foliares de nutrientes (N, K, Mg e P) e a massa de grãos por planta, massa de 100 grãos, número de vagens com dois grãos, massa seca de folhas, ramos, índice de clorofila e eficiência agronômica relativa. Com isso, a produtividade foi incrementada em 65%, em comparação ao tratamento testemunha, recomendando-se a aplicação de 100 a 125 kg ha-1 de N com ou sem R. tropici. Na área com maior teor de MOS, a inoculação com R. tropici propiciou maior massa de grãos por plantas, número de vagens com um grão, massa seca de folhas, total e índice de clorofila; a adubação nitrogenada aumentou o teor foliar de N e o índice de clorofila, mas ambos não interferiram na produtividade, não sendo recomendadas. Tais resultados indicam a dependência do manejo da adubação nitrogenada e inoculação com Rhizobium à disponibilidade natural de N na MOS.

ABSTRACT Studies related to nitrogen fertilization and biological nitrogen fixation in the increase of chickpea production are considered scarce in tropical regions. This work aimed to evaluate the inoculation with Rhizobium tropici, and nitrogen fertilization, under irrigated tropical conditions, on the development of chickpea in low and high content of soil organic matter (SOM). The experimental design was in randomized blocks, with four replications, in a 2 x 6 factorial scheme. Treatments, consisted of the presence and absence of inoculation with R. tropici, and six N doses (0, 25, 50, 75, 100, and 125 kg ha-1) in the form of urea. The study was divided into two areas with distinct contents of SOM. In the area with the lowest content of SOM (3.55 dag kg-1), the inoculation with R. tropici or the fertilization with 125 kg ha-1 N increased the leaf content of nutrients (N, K, Mg, and P) and grain mass per plant, 100-grain mass, number of pods with two grains, dry mass of leaves, branches, chlorophyll index, and relative agronomic efficiency. Thus, the yield was increased in 65%, compared to the control treatment, recommending the application of 100 to 125 kg ha-1 of N with or without R. tropici. In the area with the highest content of SOM (7.37 dag kg-1), the inoculation with R. tropici provided a higher grain mass per plants, number of pods with one gain, dry mass of leaves, total dry mass, and chlorophyll index; nitrogen fertilization increased the leaf content of N and the chlorophyll index, although neither factor interfered with the yield, and are not recommended. Such results indicate the dependence of the nitrogen fertilization and inoculation with Rhizobium on the natural availability of N in the SOM.

RESUMO Os solos do Cerrado Brasileiro são geralmente ácidos e com baixa disponibilidade de nutrientes, portanto, o uso de insumos alternativos para melhorar fertilidade deve ser investigado. Os objetivos deste estudo foram avaliar o potencial dos biochars de casca de arroz (BHR) e de esterco bovino (BCM) no aumento da disponibilidade de fósforo e seus efeitos nas propriedades químicas do solo e nas plantas de feijoeiro. Os experimentos foram conduzidos em delineamento inteiramente casualizado, em esquema fatorial 4x2+3, com quatro repetições. Os tratamentos foram quatro doses de biochar (1, 2, 3 e 4% m / v), dois biochars (BRH e BCM) e três tratamentos adicionais (C1, sem calagem e sem fertilização; C2, adição de carbonato de Ca e Mg e Fertilizantes NPK e; C3, adição de silicato de Ca e Mg e fertilizantes NK). Nas maiores doses de BRH houve aumento de 2,7, 5,3 e 2,5 vezes no teor de P extraído por Mehlich 1 e quantificado por colorimentria, por Mehlich 1 e quantificado por espectroscopia e por resina de troca iônica e quantificado por espectroscopia, respectivamente. Para as doses mais altas de BCM, os aumentos no conteúdo de P foram 51,3, 289,2 e 88,4 vezes maiores que em C1, respectivamente, de acordo com os métodos descritos para o BRH. Os biochars aumentaram o pH do solo, a CEC, os teores nutrientes e o crescimento do feijoeiro em relação ao C1, especialmente o BCM. No entanto, a produção de matéria seca foi significativamente menor do que a no C2.

ABSTRACT The soils of the Brazilian Savanna are generally acidic and have low availability of nutrients, so the use of alternative inputs to improve their fertility should be investigated. The objectives of this study were to evaluate the potential of biochars from rice husk (BHR) and from bovine manure (BCM) in increasing phosphorus availability and their effects on soil chemical properties and in common beans plants. The experiments were carried out in a completely randomized design, in a 4x2+3 factorial scheme with four replicates. The treatments were four biochar doses (1, 2, 3 and 4% m/v), two biochars (BRH and BCM) and three additional treatments (C1, no liming and no fertilization; C2, addition of Ca and Mg carbonate and NPK fertilizers and; C3, addition of Ca and Mg silicate and NK fertilizers). In the highest doses of BRH there was an increase of 2.7, 5.3 and 2.5 times in the P content extracted by Mehlich 1 and quantified by colorimentria, by Mehlich 1 and quantified by spectroscopy and by ion exchange resin and quantified by spectroscopy, respectively. For the highest doses of BCM, the increases in P content were 51.3, 289.2 and 88.4 times greater than in C1, respectively, according to the methods described for BRH. The biochars increased soil pH, CEC, nutrient content and the growth of bean plants compared to C1, especially BCM. However, the production of dry matter was significantly lower than that obtained in C2.

Resumo Os sistemas agroflorestais são utilizados para diversificar a produção de alimentos, proporcionar aumento na biodiversidade da fauna e da flora e conservação do carbono e nutrientes no solo. Sendo assim, o objetivo deste estudo foi avaliar a fertilidade e os estoques de carbono (C) e nitrogênio (N) do solo após dez anos de implantação de sistemas agroflorestais (SAFs) no Cerrado mineiro. O estudo foi realizado no Assentamento Agroextrativista Americana, localizado no município de Grão Mogol, mesorregião norte do Estado de Minas Gerais. Foram selecionados três SAFs e duas áreas de vegetação nativa (VN) adjacentes, utilizadas como referência para o estudo, as quais foram agrupados em função da classe de solo: Latossolo Vermelho Amarelo e Cambissolo Háplico. A amostragem do solo foi realizada em março de 2013, dez anos após a implantação dos SAFs, em que amostras compostas foram retiradas das camadas 0-5 e 0-20 cm de profundidade para avaliação dos teores de nutrientes e densidade aparente, e na primeira camada os estoques de C e N do solo. Os SAFs que foram implantados com manejo baseado em desrama e manutenção da diversidade florística contribuíram com e melhoria da qualidade do solo e manutenção da fertilidade e estoques de C em níveis semelhantes à vegetação nativa. Já o SAF que foi implantado com a prévia supressão da vegetação nativa reduziu a diversidade arbórea e, consequentemente, os estoques de C ao longo do tempo. Porém, o manejo com culturas anuais e uso de leguminosas contribuiu para a melhoria da fertilidade do solo e incremento dos teores e estoques de N.

Abstract Agroforestry systems are used to diversify food production, provide an increase in the biodiversity of fauna and flora as well as the conservation of carbon and nutrients in the soil. Thus, the objective of this study was to evaluate the fertility and carbon (C) and nitrogen (N) stocks of the soil after ten years of agroforestry system (SAFs) implantation in the Cerrado biome of Minas Gerais state, Brazil. The study was carried out in the American Agroextractivist Settlement, located in the municipality of Grão Mogol, northern mesoregion of the state of Minas Gerais. Three SAFs and two adjacent native vegetation areas (VNs) were used as reference for the study, which were grouped according to the soil class: Red-Yellow Latosol and Haplic Cambisol. The soil sampling was carried out in March 2013, ten years after the implementation of the SAFs, where composite samples were removed from the 0-5 and 0-20 cm soil depth layers for the evaluation of nutrient contents and apparent density, and in the first layer the soil C and N stocks. SAFs that were deployed with management based on prune trees and maintenance of floristic diversity contributed with the improvement of the soil quality and the maintenance of fertility and C stocks at levels like in native vegetation. On the other hand, the SAF that was implanted with the previous suppression of the native vegetation reduced the tree diversity and, consequently, the C stocks over time. However, management with annual crops and the use of legumes contributed to the improvement of soil fertility and to the increase of N contents and stocks.

RESUMO: O processo de pirólise da biomassa pode ser uma alternativa para o uso agrícola de lodo de esgoto. Este trabalho objetivou avaliar o uso de biochar produzido a partir da mistura de lodo de esgoto e bagaço de cana (BB, 1:1 relação lodo de esgoto e e bagaço de cana) na produção e nutrição de beterraba (Beta vulgaris L.). Conduziu-se um experimento em casa de vegetação com cinco dose de BB: 0, 2,5, 5, 7,5 e 10% v/v, e dois tratamentos adicionais, biochar de lodo de esgoto (BS, 5% v/v) e tratamento convencional (CV) com calagem e fertilizantes minerais. Após 45 dias de incubação dos solos tratados, cultivou-se as plantas por 55 dias. O biochar produzido a partir de lodo de esgoto e bagaço de cana-de-açúcar é uma tecnologia alternativa para reduzir o potencial de contaminação do lodo de esgoto e incorporar formas mais estáveis de carbono ao solo. Embora o biochar tenha aumentado à fertilidade do solo, as raízes finas e a eficiência de absorção de nutrientes pelas plantas de beterraba, a produção de matéria seca total foi significativamente menor que a obtida no tratamento convencional.

ABSTRACT: The biomass pyrolysis process may be an alternative for the agricultural use of sewage sludge. This study aimed to evaluate the use of of biochars from mixture of sewage sludge and sugarcane bagasse (BB, 1:1 relationship sewage sludge and sugarcane bagasse) on sugar beet (Beta vulgaris L.) production and nutrition. A greenhouse experiment was conducted with five application rates of BB: 0, 2.5, 5, 7.5, and 10% (v/v), and two additional treatments, biochar from sewage sludge (BS, application rate 5% (v/v)) and conventional treatment (CV) that received lime and mineral fertilizer. The treated soils were incubated for 45 days, after which, seedlings were cultivated for 55 days. Biochar produce from sewage sludge and sugarcane bagasse is an alternative technology to reduce the potential for contamination of sewage sludge and to incorporate more stable carbon forms in the soil. Although, biochar has increased soil fertility, fine roots and nutrient uptake efficiency by sugar beet plants, total dry matter yield was significantly lower than that obtained in conventional treatment.

RESUMO O grão-de-bico é a terceira leguminosa mais cultivada no mundo. No Brasil cultivos com essa leguminosa são recentes e definições de técnicas de manejo de fertilizantes são escassas. Objetivou-se avaliar a produção de grão-de-bico (BRS Aleppo) e os atributos químicos do solo sob doses de fósforo e molibdênio foliar. O delineamento utilizado foi em blocos ao acaso, com quatro repetições. Para avaliação da produção, adotou-se o esquema fatorial 2 x 5, consistindo de dois manejos da adubação, com ou sem molibdênio e cinco doses de P2O5 (0, 60, 120, 180 e 240 kg ha-1). Para avaliação dos atributos químicos do solo, considerou-se também a amostragem na linha e entre linha de semeadura. A adubação molíbdica propiciou maior massa seca de ramos e da parte aérea. As doses de fósforo aumentaram a massa seca de ramos, folhas e grãos, obtendo-se a produção máxima de 2,83 t ha-1 de grãos na dose 200 kg ha-1 de P2O5. Entretanto a máxima eficiência agronômica (8,30) foi observada com a adição de 150 kg ha-1de P. No solo da linha de cultivo obteve-se maiores teores de P, K, H+Al e P-rem, e diminuição do pH, teor de Ca, SB, T e V, em comparação àquele da entre linha. As doses de fósforo reduziram o pH do solo, aumentaram a T e os teores de P, somente na linha de cultivo, indicando a baixa mobilidade do P e a capacidade de acidificação do superfosfato em solos alcalinos.

ABSTRACT Chickpea is the third most cultivated legume in the world. In Brazil, cropping of this legume is recent and definitions of fertilizer management techniques are scarce. In this study, the objective was to evaluate chickpea (BRS Aleppo) production and soil chemical attributes with and without phosphorus fertilization and leaf-applied molybdenum. A randomized block experimental design was used, with four replications. A 2 x 5 factorial arrangement was used to evaluate production, consisting of two molybdenum fertilization management practices (with and without molybdenum) and five application rates of P2O5 (0, 60, 120, 180, and 240 kg ha-1) in the form of single superphosphate. Soil sampling for evaluation of soil chemical attributes in the crop row and between rows was also considered. Molybdenum fertilization brought about greater stem and aboveground dry matter. Phosphorus fertilization increased stem, leaf, and seed yield, yielding a maximum of 2.83 t ha-1 seed at the rate of 200 kg ha-1 P2O5. However, maximum agronomic efficiency (8.30) was observed with the addition of 150 kg ha-1 P. Soil in the crop row attained higher concentrations of P, K, H+Al, and P-rem and reduction in pH, Ca concentration, SB, T, and V compared to between rows. Phosphorus rates reduced soil pH and increased T and the P concentrations, though only in the plant row. Between the rows, no changes were observed in soil chemical attributes, indicating low mobility of P and the acidification capacity of superphosphate in alkaline soils.

ABSTRACT The aim of this study was to evaluate the soil microbiological attributes of two Agroforestry Systems (AFS) in the city of Grão Mogol-MG considering two soil classes (Udox and Aqualf). Three composite samples were collected from the 0-5 cm soil depth layer. Each sample was subsequently divided into five replications to evaluate the carbon of soil microbial biomass (SMB-C), metabolic quotient (qCO2), microbial quotient (qMIC), basal respiration (SBR) and the soil CO2 efflux. The microbiological attributes of the soil were more influenced by the season than by the AFS group. The BMS-C and SBR were higher in the dry season while the CO2 efflux was higher during the rainy season. The similar values of the microbiological attributes between the evaluated systems indicate that AFS are efficient at incorporating carbon and maintaining the soil biological activity similar to that of native vegetation areas.

RESUMO: A produção de biochar a partir de resíduos orgânicos pode ser uma estratégia agronômica interessante como fonte de nutrientes para as plantas, diminuindo assim, a pressão sobre os recursos naturais. Com o objetivo de avaliar o efeito de biocarvões, produzidos de materiais filtrantes descartados, no crescimento e produção de feijão (Phaseolus vulgaris L.), conduziram-se simultaneamente três experimentos em casa de vegetação. Cada um dos experimentos foi representado pela aplicação de um biochar, os quais foram produzidos a partir de resíduos orgânicos de casca de arroz, serragem e restos de silagem de sorgo, utilizados como material filtrante para o biofertilizante suíno; e os tratamentos avaliados consistiram na adição de cinco níveis de biocarvão, isto é, 0, 2,5%, 5% 7,5% e 10% v/v. Nos três experimentos a aplicação de biochar aumentou a massa seca da raiz, massa seca da parte aérea, massa seca de grãos, número de vagens e número de grãos. Esses resultados indicam que os biochars contribuíram significativamente para o crescimento e produção do feijoeiro.

ABSTRACT: Production of biochar from organic wastes promises to be an interesting source of plant nutrients, thus reducing pressure on natural resources. To assess the effect of biochar prepared from wastes filtration materials on the growth and production of common bean (Phaseolus vulgaris L.), three simultaneous greenhouse experiments were conducted with three different biochar from organic wastes (rice husk, sawdust, and sorghum silage) using as filtration material for swine biofertilizer. In each experiment the treatments consisted of the addition of five different biochar concentrations (0%, 2.5%, 5%, 7.5%, and 10% v/v), arranged in a completely random design, with four repetitions. Application of biochar increased the root dry mass, shoot dry mass, grain dry mass, number of pods and number of grains. These results indicated that biochar contributed significantly to the growth and production of common bean plants.

ABSTRACT: The production of biochar from organic residues promises to be an interesting strategy for the management of organic waste. To assess the effect of biochar on soil properties and the production and nutrition of common bean (Phaseolus vulgaris L.), three simultaneous experiments were conducted in a greenhouse with different biochar from organic residues (rice husk, sawdust, and sorghum silage) used as filtration material for swine biofertilizer. In each experiment the treatments consisted of five different biochar concentrations (0, 25, 50, 75 and 100 L m−3), arranged in a completely randomized design, with four repetitions. In the experiments, the use of biochar increased soil pH, cation exchange capacity, nutrient availability in the soil, and nutrient accumulation in grains. The biochar concentrations corresponding to the maximum production of grain dry matter of bean plants were 100, 68, and 71 L m−3 for biochar from rice husk filter (BRHF), biochar from sawdust filter (BSF), and biochar from sorghum silage filter (BSSF), respectively.

Resumo O objetivo deste trabalho foi avaliar os efeitos da mudança de uso da terra na dinâmica do carbono orgânico, no nitrogênio total e em atributos microbiológicos do solo ao longo do tempo, em cultivos irrigados de cana-de-açúcar. Os sistemas foram avaliados em quatro áreas com cana-de-açúcar, numa cronossequência com 5, 7, 8 e 9 anos de cultivo, além de uma área com vegetação nativa. As amostras foram analisadas quanto ao estoque de C e N e quanto às propriedades microbiológicas do solo. O sistema com 8 anos apresentou os maiores valores de C na biomassa microbiana e de respiração basal, bem como os menores de quociente metabólico (qCO2). Já os maiores valores de estoque de C e N foram observados na área com vegetação nativa. Estes resultados estão associados à deposição constante de serrapilheira e à intensa atividade biológica na vegetação nativa. A deposição de palhada de cana-de-açúcar sobre a superfície, ao longo tempo, melhorou a qualidade do solo e manteve os estoques de C e N semelhantes aos observados na área de vegetação nativa.

Abstract The objective of this work was to evaluate the effects of land use change on the dynamics of organic carbon, on total nitrogen, and on microbial soil properties over time, in irrigated sugarcane crops. The systems were evaluated in four areas with sugarcane in a chronosequence of 5, 7, 8, and 9 years of cultivation, besides a native vegetation area. The soil samples were analyzed for C and N stocks, and for the microbiological properties of the soil. The system with 8 years showed the highest C values of microbial biomass and basal respiration, and the lowest ones for microbial metabolic quotient (qCO2). The highest values of C and N stocks were observed in the native vegetation area. These results are associated with the constant deposition of litter and intense biological activity in the native vegetation. The deposition of sugarcane straw on the soil surface, over time, improved soil quality and kept the soil stocks of C and N similar to those observed in the native vegetation area.