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 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.

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.