Eduardo da Silva Matos

O compartimento terrestre é o maior reservatório de carbono no solo e armazena cerca de três vezes mais que o compartimento atmosférico. Porém, a atmosfera tem aumentado suas concentrações, devido as elevadas emissões de gases de efeito estufa, decorrente principalmente do consumo de combustíveis fosseis e queimadas das florestas. O Brasil é um dos maiores emissores, especialmente de dióxido de carbono, pelo qual o setor de mudanças do uso da terra e florestas são responsáveis majoritariamente pelas emissões. O solo em condições naturais tem um equilíbrio entre a entrada e saída de carbono, no entanto quando o solo é cultivado, principalmente com sistemas convencionais, há uma perda significativa dos estoques de carbono do solo. No entanto, quando é adotado manejos conservacionistas ocorre o mecanismo de proteção física do carbono através da formação e estabilização dos agregados, que dificulta o acesso dos microrganismos a decomposição e mantém estocado no solo, o que mitiga a emissão para atmosfera. Diante do exposto, este trabalho teve como objetivo mostrar como os manejos influenciam no estoque de carbono no solo, e como é atuação do mecanismo de proteção física de agregados em sistemas conservacionistas, demostrando como foram os avanços na pesquisa da interação da matéria orgânica com a formação e estabilização de agregados. Stock and Mechanism of Physical Protection of Soil Carbon in Agricultural Managements A B S T R A C TThe terrestrial compartment is the largest carbon reservoir in the soil and stores about three times as much as the atmospheric compartment. However, the atmosphere has increased its concentrations, due to the high emissions of greenhouse gases, mainly due to the consumption of fossil fuels and forest fires. Brazil is one of the largest emitters, especially of carbon dioxide, for which the sector of land use change and forests are responsible for the majority of emissions. Soil under natural conditions has a balance between carbon input and output, however when the soil is cultivated, mainly with conventional systems, there is a significant loss of soil carbon stocks. However, when conservation management is adopted, there is a mechanism for the physical protection of carbon through the formation and stabilization of aggregates, which hinders the access of microorganisms to decomposition and keeps them stored in the soil, which mitigates the emission into the atmosphere. In view of the above, this study aimed to show how the management influences the carbon stock in the soil, and how the mechanism of physical protection of aggregates in conservationist systems works, demonstrating how advances were made in researching the interaction of organic matter with formation and stabilization of aggregates.Key words: aggregates, carbon dioxide, greenhouse effect, crop-livestock-forest integration, organic matter

The objective of this work was to evaluate whether balsa wood plantation and its fertilization can improve soil carbon stocks. Total carbon stocks in the soil-biomass system, at 0.0-0.30 m soil depths, were evaluated under three fertilization strategies, after three and seven years, and compared with carbon stocks from native forest and degraded pasture. At the highest fertilization level, balsa wood showed a carbon stock similar to that of the native forest (65.38 Mg ha-1) and, after seven years, it increased carbon stock by 18% in the soil, and by 42% in the soil-biomass system.

In order to clarify the effect of mixed planting in the dynamics of phosporus (P), we assessed the fractions of this element in mixed plantings of Eucalyptus urophylla × E. grandis (Urograndis) and...

The increase of greenhouse gases in the atmosphere raises the average temperature of the planet, triggering problems that threaten the survival of humans. Protecting the global climate from the effects of climate change is an essential condition for sustaining life. For this reason, governments, scientists, and society are joining forces to propose better solutions that could well-rounded environmentally, social and economic development relationships. International climate change negotiations involve many countries in establishing strategies to mitigate the problem. Therefore, understanding international negotiation processes and how ratified agreements impact a country is of fundamental importance. The purpose of this paper is to systematize information about how climate negotiations have progressed, detailing key moments and results, analyzing the role that Brazil played in the course of these negotiations and the country’s future perspectives.

The aim of this study was to investigate soil C and N stocks and soil physical properties under a cotton (Gossypium hirsutum) based system using no‐till (NT) and conventional tillage (CT). The experiment was established as a randomized block design with four replications of six treatments as follows: [NT1], NT system with crop rotation of cotton/soybean (Glycine max)/maize (Zea mays) + brachiaria (Brachiaria ruziziensis); [NT2], NT system with crop rotation of soybean/maize + brachiaria/cotton; [NT3], NT system with crop rotation of maize + brachiaria/cotton/soybean; [CR1], CT with annual rotation (soybean/cotton); and [CR2], CT with biannual rotation (soybean/soybean/cotton) and [CT1] CT with cotton monoculture. An area of native Cerrado vegetation was used as the reference or baseline. Soil samples were obtained from 0‐ to 5‐, 5‐ to 10‐, 10‐ to 20‐, 20‐ to 30‐, 30‐ to 60‐, and 60‐ to 100‐cm depths. After 9 years of cultivation, soil under NT systems contained higher C concentrations than those under CT (p < 0.05); however, significant differences were restricted to the 0‐ to 5‐cm layer. Stocks of C and N in the 0‐ to 30‐cm depth ranged from 36.2 to 39.8 Mg ha⁻¹and from 2.00 to 2.22 Mg ha⁻¹, respectively. Despite higher C concentration in the upper layer, NT treatments (NT1, NT2, and NT3) had soil C stocks similar to those of CR1 and CT1. In comparison with Cerrado, C stocks in soil under all cultivated treatments were reduced by 27% in the top 1‐m depth, which represents a C loss of 35 Mg C ha⁻¹upon conversion from the Cerrado to cultivated land. The least soil bulk density among all treatments was observed for NT1. However, there were no differences in macroporosity and microporosity among NT and CT systems even after 9 years of cultivation. In comparison with CT, principal benefits of NT systems for C sequestration and soil physical improvements are restricted to the surface layer.

Objetivou-se comparar o sistema de integração lavoura-pecuária-floresta com sistemas exclusivos quanto à assimilação e manutenção do carbono orgânico total (COT) e carbono lábil (CL), após o segundo ano de estabelecimento. Os tratamentos constituíram os seguintes sistemas de produção: floresta de eucalipto (EUC), pastagem com Brachiaria brizantha (PAST), lavoura de soja-milho consorciada com B. brizantha (LAV) e integração lavoura-pecuária-floresta (ILPF). Uma área de fragmento florestal nativo (Mata) e uma de pousio (Pousio) foram utilizadas como referência. A área sob cultivo de EUC obteve o menor teor de COT na camada 0-5cm, enquanto LAV e PAST apresentaram os maiores teores. Por sua vez, os teores de COT para o sistema ILPF, na camada 0-5cm, ficou em uma posição intermediária aos demais. A conversão da vegetação nativa para em cultivo agrícola e florestal contribuiu para a redução dos estoques de COT no solo em 20% na camada de 0-30 cm, representando uma perda de 17,4 Mg ha-1. O efeito do componente florestal na distribuição horizontal do estoque de COT dentro do ILPF foi favorecido no sentido sul, tendência não verificada para CL. Em curto prazo, os impactos dos sistemas conservacionistas sobre os teores de COT e CL do solo foram identificados apenas na camada superficial.Palavras-chave: agrossilvipastoril; permanganato de potássio; matéria orgânica do solo LABILE AND TOTAL CARBON POOLS IN SOIL UNDER INTEGRATED CROP-LIVESTOCK-FOREST SYSTEM IN THE CERRADO/AMAZONIA ECOTONE The aim of this experiment was to evaluate the carbon assimilation and maintenance among an integrated crop-livestock-forest system and nonintegrated systems through the pools of total soil organic carbon (COT) and labile carbon (CL) after the second year of establishment. Treatments comprised the following production systems: eucalyptus forest (EUC), Brachiaria brizantha pasture (PAST), soybean-corn tillage intercropping with B. brizantha (LAV) and integrated crop-livestock-forest system (ILPF). An area of native forest fragment (Mata) and a fallow area (Pousio) were used as references. The effects of the forest component on the COT and CL pools in the ILPF were also evaluated. The area under EUC had the lowest concentration of COT in 0-5cm layer, while LAV and PAST showed higher concentrations. Conversion of natural vegetation to cultivated systems reduced soil C stock by 20% in the 0-30 cm layer which corresponded to 17.4 Mg ha-1. The results suggest that the effect of forest component in the horizontal distribution of the TOC stock was favored in the south face of the ILPF, but this trend was not observed for CL. In a short term, the effects of ILPF on COT and CL pools were not statistically detectable.Keywords: agrosilvopastoral, soil organic matter, potassium permanganate. DOI: http://dx.doi.org/10.5935/2318-7670.v05nespa09

Objetivou-se comparar o sistema de integração lavoura-pecuária-floresta com sistemas exclusivos quanto à assimilação e manutenção do carbono orgânico total (COT) e carbono lábil (CL), após o segundo ano de estabelecimento. Os tratamentos constituíram os seguintes sistemas de produção: floresta de eucalipto (EUC), pastagem com Brachiaria brizantha (PAST), lavoura de soja-milho consorciada com B. brizantha (LAV) e integração lavoura-pecuária-floresta (ILPF). Uma área de fragmento florestal nativo (Mata) e uma de pousio (Pousio) foram utilizadas como referência. A área sob cultivo de EUC obteve o menor teor de COT na camada 0-5cm, enquanto LAV e PAST apresentaram os maiores teores. Por sua vez, os teores de COT para o sistema ILPF, na camada 0-5cm, ficou em uma posição intermediária aos demais. A conversão da vegetação nativa para em cultivo agrícola e florestal contribuiu para a redução dos estoques de COT no solo em 20% na camada de 0-30 cm, representando uma perda de 17,4 Mg ha-1. O efeito do componente florestal na distribuição horizontal do estoque de COT dentro do ILPF foi favorecido no sentido sul, tendência não verificada para CL. Em curto prazo, os impactos dos sistemas conservacionistas sobre os teores de COT e CL do solo foram identificados apenas na camada superficial

Resumo O objetivo deste trabalho foi avaliar, em condição de chuva natural, a perda de solo e água em sistemas de produção com integração lavoura-floresta ou com sucessão soja-milho. O experimento foi realizado em Latossolo Vermelho-Amarelo com textura muito argilosa, em uma região de transição Cerrado/Amazônia. Os seguintes usos e coberturas do solo foram avaliados: sistema integração lavoura-floresta; lavoura com sucessão soja-milho+braquiária; e solo descoberto. As lavouras foram cultivadas em sistema plantio direto em sucessão soja-milho+braquiária, todos os anos, independentemente do sistema de produção. A perda de solo por erosão hídrica, nos três anos avaliados, foi de 0,215 Mg ha-1 por ano, no sistema integração lavoura-floresta, e de 0,753 Mg ha-1 por ano na lavoura com sucessão soja-milho. Estes valores situaram-se abaixo do limite de tolerância, que é de 11,1 Mg ha-1 por ano, e os menores valores observados com a integração lavoura-floresta apontam para o elevado potencial conservacionista desse sistema.

In temperate regions, cultivation of Robinia pseudoacacia L. has recently received considerable attention because it is a fast-growing species for biomass and bioenergy production, while acting as a potential carbon (C) sink to counterbalance carbon dioxide (CO₂) emissions and an alternative to agricultural crops on marginal sites. The objective of our work was to compare total organic carbon (TOC), total nitrogen (TN), and organic C fractions in postlignite mining soils under different development stages of R. pseudoacacia. Soil samples from three different depths (0–3, 3–10 and 10–30 cm) were taken in plantations 2, 3, 4, and 14 years old (R2, R3, R4, and R14, respectively). The TOC and TN contents increased with increasing tree age in all layers (P < 0.01). In the top 30 cm, TOC and TN stocks ranged from 11.7 to 59.8 Mg C ha⁻¹ and from 0.30 to 2.61 Mg N ha⁻¹ at R2 and R14, respectively. The rate of C sequestration was calculated to be 4.0 Mg C ha⁻¹ year⁻¹. Microbial biomass C and N were strongly correlated to TOC (r² = 0.96 – 0.81; P < 0.001) and TN contents (r² = 0.92 – 0.91; P < 0.001). The light fraction C (C_LF) accounted for 15–30% and the heavy fraction C for 70% of TOC in all layers. In the 0- to 3-cm layer, C_LF increased by 0.5 g kg⁻¹ year⁻¹. The results indicate that plantations of R. pseudoacacia are an attractive alternative to increase soil C contents in reclaimed lignite mining soils. In the short term, microbial biomass C and light fraction C are sensitive and provide an appropriate measure to assess soil C changes caused by cultivation of R. pseudoacacia.