Improving the quality of organic compost of sewage sludge using grass cultivation followed by composting.

Composting is one of the main processes of stabilization of sewage sludge and its association with cultivation in this residue has a great potential to produce stabilized organic fertilizer and, or substrate for plant development. The aim of this work was to evaluate the physical, chemical, and microbial attributes of sewage sludge (SS) aerated and cultivated with Pennisetum purpureum or Urochloa brizantha and, later, composted. The study was installed in a 2x2+2 factorial scheme, with four replications. The factors consisted of cultivation of P. purpureum or U. brizantha in SS for 90 days, with or without intermittent aeration for 60 days. The control treatments were SS without cultivation, with the presence or absence of aeration. After 90 days of cultivation, the grass was cut, crushed, and incorporated into the SS for composting for 60 days. The composted sewage sludge showed an increase of 26, 24, 17, 123, 19, 32, and 7.7% in the levels of P, Ca, Cu, Fe, Mn, Zn, and Pb; and a reduction of 22, 5.2, 26, 30, 8.8, and 70% in the levels of C, N, K, Mg, Ni, and Na, respectively. The levels of Cu, Ni, Zn, and Pb remained below the maximum limit allowed by environmental resolution. The degradation of SS decreased the particle diameter, increasing the bulk density and total porosity, improving the physical properties of the compost. The SS cultivation and composting, regardless of the grass, led to a reduction in pH, basal and accumulated respiration, nitrification index, and C/N ratio and an increase in the CEC/C ratio, showing adequate maturation of the compost produced. Thus, the SS cultivation and composting with grasses were effective for producing matured and quality organic compost with low risk of environmental contamination.

Biochar-cadmium retention and its effects after aging with Hydrogen Peroxide (H2O2).

Cadmium (Cd) is a highly toxic heavy metal that can become available to the environment from a variety of sources. The thermal transformation of organic residues into biochar can be a sustainable way to reduce cadmium environmental availability and, at the same time, a waste management solution. We studied sixteen biochars in two versions: unaged and aged with hydrogen peroxide (H2O2), regarding their Cd retention capacity. Feedstocks used included softwood biochar (SWB), almond shell (ASB), walnut shell (WSB), sewage sludge (SSB), and coconut shell (CSB); production temperatures varied from 450 to 900 °C. The objectives of this research were to understand the role of biochar properties on Cd adsorption rates and to evaluate how properties and adsorption rates vary as a function of H2O2 aging. Feedstock played a more important role than production temperature in determining biochar properties. Cd-adsorption capacity ranged from 0.67 to 415.67 mg/g, and the biochars that adsorbed the most Cd were SSB 700, SWB 800 - i, CSB 600 - m2, ASB 500-1, CSB 600 - m3, WSB 900, and CSB 600. The properties that best explained this variation in Cd retention were ash, sulfur, nitrogen and carbon content. Variation in oxygen content, cation exchange capacity and surface area had less impact of Cd adsorption. The H2O2 aging caused oxygen content to increase in all biochars, but the increase in Cd retention was not significant for the majority of the biochars and aging even reduced the Cd retention in some. Our results may help design biochars with maximized sites for Cd adsorption.

Rhizosphere microbiological processes and eucalypt nutrition: Synthesis and conceptualization.

In this review, we present the state of art regarding rhizosphere effects on eucalypt plantations. It provides a greater understanding of carbon (C) and nitrogen (N) turnover in forest soils. P organic hydrolysis, soil mineral solubilization, indoleacetic acid, gibberellin, resistance factors, and production of siderophores by rhizosphere microbial populations help to explain the tolerance of Eucalyptus plants to biotic and abiotic stresses and the apparent steady-state condition of C and N soil stocks in many planted forests. This work aims to present the main findings on Eucalyptus rhizosphere processes and highlights their importance for trees nutrition, especially for N mineralization triggered by microbial activation or microbial community structure changes regarding the so-called rhizosphere priming effect and N fixation. Furthermore, we present an explanatory conceptual model of the steady-state condition for soil organic matter (SOM) stocks and its relation with fertilization based on a nutrient balance model. This review also considers the main experimental and modeling studies that demonstrate the quantitative importance of rhizosphere processes to Eucalyptus genus and their shortcomings. This provides a framework for process modeling under scenarios of global climate change. A better understanding of rhizosphere microbiological processes may allow improvements in Eucalyptus nutrition and production, as well as in accurate long-term estimates of SOM stocks and C-CO2 exchanges between forest soils and the atmosphere.

Biochar in sugar beet production and nutrition / Biochar na produção e nutrição da beterraba

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 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.

Growth and production of common bean fertilized with biochar / Crescimento e produção de feijoeiro adubado com biocarvão

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.

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.

Caracterização e estoques de carbono de sistemas agroflorestaisno Cerrado de Minas Gerais / Characterization and carbon storage of agroforestry systems in brazilian savannas of Minas Gerais, Brazil

Os sistemas agroflorestais (SAFs) além de geração de renda e conservação da biodiversidade pode ser uma alternativa para a estocagem de carbono. O trabalho teve como objetivo caracterizar três sistemas agroflorestais (SAFs) e estimar os estoques de carbono na fitomassa aérea, na serapilheira e no solo. Os SAFs e suas respectivas vegetações nativas adjacentes foram caracterizados quanto ao número, classificação botânica,distribuição diamétrica e estratificação vertical dos indivíduos arbóreose. Em cada um dos sistemas, foram estimados os estoques de carbono na fitomassa aérea, na serapilheira e no solo. Os SAFs,implantados a partir do manejo da vegetação nativa, apresentaram uma biodiversidade vegetal e estoque de carbono na fitomassa, na serapilheira e no solo semelhantes à área de vegetação nativa adjacente. Por outro lado, os estoques de carbono no SAF implantado em área anteriormente cultivada com culturas anuais apresentou menor diversidade de espécies arbóreas e estoques de carbono na fitomassa, serapilheira e no solo, em relação à vegetação nativa adjacente. Sistemas agroflorestais bem manejados se assemelham à vegetação nativa em estoque de carbono e conservação da biodiversidade dos recursos naturais.

Agroforestry systems (SAFs) as well as income generation and biodiversity conservation can be an alternative to carbon stocks. The study aimed to characterize and estimate the soil and plant carbon stocks of SAFs in Brazilian savannas of Minas Gerais State, Brazil. Three agroforestry systems and their adjacent native vegetation were evaluated. In addition, the forest inventory, the diameter distribution and vertical stratification of tree species were measured. The SAFs deployed from the management of native vegetation had a plant biodiversity and carbon stock in biomass, litter and soil similar to that of the adjacent area of native vegetation. On the other hand, carbon stocks in SAF deployed in the area cultivated with annual crops had lower species diversity and carbon stocks in biomass, litter and soil in relation to native vegetation adjacent. Agroforestry systems well managed have carbon stocks and biodiversity of natural resources like native vegetation.

Atributos químicos do solo adubado com lodo de esgoto estabilizado por diferentes processos e cultivado com girassol / Soil chemical attributes fertilized with sewage sludge stabilized by different processes and cultivated with sunflower

Objetivou-se com este trabalho avaliar os atributos do solo em resposta a adubação com lodo de esgoto submetido a diferentes processos de estabilização. O experimento foi desenvolvido em solo CAMBISSOLO HÁPLICO, com os tratamentos: testemunha (sem adubação), adubação com lodo de esgoto solarizado, adubação com lodo de esgoto compostado, adubação com lodo de esgoto vermicompostado, adubação com lodo de esgoto caleado e adubação química recomendada para a cultura. Utilizou-se o delineamento experimental em blocos casualizados, com 4 repetições. O lodo de esgoto estabilizado de diferentes formas não influenciou os teores de matéria orgânica, o pH, a soma de bases (SB), a saturação por bases (V), a CTC efetiva (CTC(t)), a CTC potencial (CTC(T)) e os teores de H+Al do solo quando comparado à adubação química e ao tratamento sem adubação, exceto o lodo de esgoto caleado, que aumentou o pH, a SB, a V e a CTC(t) do solo.

The objective of this study was to evaluate the soil properties in response to fertilization with sewage sludge under different stabilization processes. The experiment was conducted in Haplic Cambisol, with the treatments: control (without fertilization), fertilization with sewage sludge solarized, fertilization with compost sewage sludge, fertilization with sewage sludge vermicomposted, fertilization with limed sewage sludge and chemical fertilizer recommended for culture. It was used a randomized block design with four replicates. The sewage sludge did not affect the organic matter content, pH, SB, V%, CTC(t), CTC(T) and the contents of H + Al when compared to chemical fertilizer and treatment without fertilization, except the limed sewage sludge, which increased the pH, SB, CTC(t), and V% of the soil.

Produção de porta-enxerto de limão cravo em resposta a adubação organomineral / Produced of rootstock of raugpur lime in response to organic-mineral fertilization

A adubação do substrato pode permitir a obtenção de porta-enxertos de alta qualidade de limão cravo. O presente trabalho teve como objetivo avaliar a produção de porta-enxerto de limão cravo (Citrus limonia Osbeck), em resposta a aplicação em cobertura, de doses de um adubo organomineral, a base de turfa. O experimento foi conduzido em casa de vegetação, sendo as sementes plantadas em tubetes de 50 mL, preenchidos por substrato comercial a base de casca de Pinus e turfa. O delineamento experimental utilizado foi o inteiramente casualizado com 5 tratamentos, 5 repetições e 8 plantas por unidade experimental. Os tratamentos utilizados foram doses (0; 0,5; 1,0; 1,5; 2,0 mL) do produto comercial diluído em 1 litro de água, sendo aplicado 5 mL por tubete semanalmente. As adubações iniciaram aos 70 dias após a semeadura e aos 115 dias foram avaliadas as alturas da planta, número de folhas, diâmetro do caule e massa seca da parte aérea e da raiz e relação entre estas. Para a produção de portas-enxerto vigorosos de limão cravo pode ser aplicado, em cobertura no substrato, uma solução de 2,0 mL do adubo organomineral.

The fertilization of substrate can provided high quality of raugpur lime tree rootstock. This work has the objective to evaluate the production of the raugpur lime tree rootstock (Citrus limonia Osbeck), in response to broadcasting application to organic-mineral fertilizer of substrate. The experiment was developed in a greenhouse conditions in pots filled with commercial substratum based on Pinus rind and turf. The completely randomized experimental design with 5 treatments and, 5 replications and 8 plants per pot was use. The treatments were doses (0; 0.5; 1.0; 1.5; 2.0 mL) of a dilute commercial fertilizer in 1 liter of water, being applied 5 mL in each pot weekly. Fertilizations started 70 days after sowing and 115 days evaluations were perfomed which consisted of plant height, leaf number, diameter stem, weight of the root and shoot dry matter and relationship between these. For the production of vigorous rangpur lime tree rootstock can be applied in brodcasting the substrate, a solution of 2.0 mL of organic mineral fertilizer

Rendimento de feijão e alterações no pH e na matéria orgânica do solo em função de doses de composto de resíduo de algodão / Yield of bean plant and changes in pH and soil organic matter as a function of doses of compost cotton waste

O objetivo do presente trabalho foi avaliar o rendimento de feijão e as alterações no pH e na matéria orgânica do solo após a aplicação do composto de resíduo de algodão. Para tanto, instalou-se o experimento em condições de campo, em um Argissolo Vermelho-Amarelo. O delineamento experimental foi em blocos ao acaso com cinco tratamentos constituídos por doses (0, 20, 40, 60, 80t ha-1) de resíduo de algodão compostado oriundo da indústria têxtil, com cinco repetições. Verificou-se que a aplicação do resíduo de algodão compostado promoveu melhoria nas características produtivas do feijoeiro submetido ao manejo orgânico e elevou os valores de pH e matéria orgânica do solo. Desse modo, o composto utilizado mostrou-se como uma alternativa para a adubação da cultura.

The objective of this research was to evaluate the yield of bean plants and changes in pH and soil organic matter after compost cotton waste application. An experiment was carried out in an Acrisol. The experimental design was of randomized blocks with five levels of cotton waste compost (0, 20, 40, 60, 80t ha-1) from the textile factory, in five replications. The application of the cotton waste compost promoted increase in the growth and productive characteristics in bean crop, and increased the pH values and soil organic matter. Thus, the compost showed as an alternative for fertilization of the culture.