Soil carbon sequestration in grass and grass-legume pastures in the western Brazilian Amazon.

Land use change from native forests to pastures in the tropics have impact on global carbon (C) cycle through increased rates of C emissions to the atmosphere and the loss of above- and belowground C accumulation and storage capacity (SILVER et al., 2000). This study was conducted to determine the carbon stock in a Ultisol under a pure Brachiaria humidicola (Rendle) Scheick pasture and a mixed pasture of B. humidicola and Arachis pintoi Krapov. & W. C. Greg cv. BRS Mandobi, both without fertilization.

Soil carbon stock in integrated crop-livestock-forest system in the Central Region of Minas Gerais.

2016

Soil carbon stock and origin in tropical soil under sugar cane management afther deforestation.

2008

Soil carbon and nitrogen in pasture soil reforested with eucalyptus and guachapele.

Apesar de os teores de matéria orgânica serem normalmente baixos em solos arenosos, ela é responsável por quase a totalidade da CTC, armazenamento de água e disponibilidade de nutrientes desses solos. A avaliação de sistemas de exploração florestais alternativos, com vistas em incrementar a acumulação de C e N, devem ser incentivados. Este estudo compara plantios puros e mistos de Eucalyptus grandis e Pseudosamanea guachapele, leguminosa fixadora de N2, em relação os estoques de C e N do solo. Os plantios foram realizados em áreas anteriormente manejadas com Panicum maximum num Planossolo, que, por pelo menos dez anos, não recebeu qualquer fertilizante. Para estimar o C e o N estocado, foram retiradas amostras das camadas de 0-2,5; 2,5-5,0; 5,0-7,5; 7,5-10,0; 10,0-20,0 e 20,0-40,0 cm tanto nos plantios puros e mistos, quanto na área de pasto. A técnica da abundância natural do 13C foi utilizada na estimativa do C originado das árvores nos 10 cm superficiais. Os estoques de C e N, no plantio misto atingiu valores de 23,83 e 1,74 Mg ha-1, respectivamente. Nos puros, de guachapele e eucalipto, e no pasto os estoques de C estimados foram de 14,20; 17,19 e 24,24 Mg ha-1, respectivamente. Para os mesmos tratamentos, os estoques de N foram estimados em 0,83; 0,99 e 1,71 Mg ha-1, respectivamente. Mais de 40 % do C do solo sob o plantio misto foram estimados como sendo derivados das árvores, enquanto nos plantios puros de eucalipto e guachapele, a contribuição do C das árvores ficou em 19 e 27 %, respectivamente. Esses resultados evidenciam que a presença da leguminosa no plantio consorciado aumenta os estoques de C e N do solo.

Carbon sequestration associated to the land-use and land-cover changes in the forestry sector in Southern Brazil.

We studied the Paraíba do Sul river watershed , São Paulo state (PSWSP), Southeastern Brazil, in order to assess the land use and cover (LULC) and their implication s to the amount of carbon (C) stored in the forest cover between the years 1985 and 2015. Th e region covers a n area of 1,395,975 ha . We used images made by the Operational Land Imager (OLI) sensor (OLI/Landsat - 8) to produce mappings , and image segmentation techniques to produce vectors with homogeneous characteristics. The training samples and the samples used for classification and validation were collected from the segmented image. To quantify the C stocked in aboveground live biomass (AGLB) , we used an indirect method and applied literature - based reference values. The recovery of 205,690 ha of a secondary Native Forest (NF) after 1985 sequestered 9.7 Tg (Teragram) of C . Considering the whole NF area (455,232 ha), the amount of C accumulated al ong the whole watershed was 3 5 .5 Tg , and the whole Eucalyptus crop (EU) area (113,600 ha) sequester ed 4. 4 Tg of C. Thus, the total amount of C sequestered in the whole watershed (NF + EU) was 3 9 . 9 Tg of C or 1 45 . 6 Tg of CO 2 , and the NF areas were responsible for the large st C stock at the watershed (8 9 %). Therefore , the increase of the NF cover contribut es positively to the reduction of CO 2 concentration in the atmosphere, and Reducing Emissions from Deforestation and Forest Degradation (REDD + ) may become one of the most promising compensation mechanisms for the farmers who increased forest cover at their farms.

Soil organic carbon, carbon stock and their relationships to physical attributes under forest soils in Central Amazonia.

The soil carbon under Amazonian forests has an important roles in global changing, making information on the soil content and depths of these stocks are considerable interest in efforts to quantify soil carbon emissions to the atmosphere.This study quantified the content and soil organic carbon stock under primary forest up to 2 m depth, at different topographic positions, at Cuieiras Biological Reserve, Manaus/ ZF2, km 34, in the Central Amazon, evaluating the soil attributes that may influence the permanence of soil carbon. Soil samples were collected along a transect of 850 m on topographic gradient Oxisol (plateau), Ultisol (slope) and Spodosol (valley). The stocks of soil carbon were obtained by multiplying the carbon content, soil bulk density and trickiness of soil layers. The watershed was delimited by using STRM and IKONOS images and the carbon contend obtained in the transects was extrapolated as a way to evaluate the potential for carbon stocks in an area of 2678.68 ha. The total SOC was greater in Oxisol followed by Spodosol and Ultisol. It was found direct correlations between the SOC and soil physical attributes. Among the clay soils (Oxisol and Ultisol), the largest stocks of carbon were observed in Oxisol at both the transect (90 to 175.5 Mg C ha-1) as the level of watershed (100.2 to 195.2 Mg C ha-1). The carbon stocks under sandy soil (Spodosol) was greater to clay soils along the transect (160-241 Mg C ha-1) and near them in the Watershed (96.90 to 146.01 Mg C ha-1).

Integração lavoura-pecuária-floresta como estratégia para aumentar a produtividade e prover serviços ambientais no noroeste do Paraná.

RESUMO: Os solos da região Noroeste do Paraná apresentam cerca de 85 a 90% de areia e níveis críticos de nutrientes, conferindo alta suscetibilidade à erosão e baixa capacidade de armazenamento de água. Além disso, a região apresenta clima quente, tornando-a bastante vulnerável a estresses abióticos. Uma das estratégias para aumentar a produtividade e, ao mesmo tempo, incrementar serviços ambientais é aumentar a diversidade de atividades, por meio do sistema de integração lavoura-pecuária-floresta (iLPF). O sistema iLPF pode conferir maior taxa de sequestro de carbono, conservação da biodiversidade e melhoria da qualidade do solo, água e ar, em comparação a sistemas não integrados. No município de Santo Inácio, PR, foram conduzidas por cinco anos duas áreas com sistema iLPF. Nos três primeiros anos de condução, foi possível conciliar a produção de grãos (soja), forragem (Brachiaria ruziziensis e B brizantha ) e madeira (eucalipto), sem que um componente prejudicasse o outro. A partir do terceiro ano, as árvores interferiram expressivamente na produtividade de grãos e forragem, indicando a necessidade de redução do número de árvores por área. O iLPF é um sistema de produção relevante para aumentar a provisão de bens e serviços ecossistêmicos na região Noroeste do Paraná, mas que ainda precisa de ajustes tecnológicos para incrementar os ganhos econômicos e ambientais. ABSTRACT: Most soils in Northwest of Paraná state, Brazil, are sandy (85 to 90% sand), with critical nutrient levels, high susceptibility to erosion and low water storage capacity Moreover, the region?s warm weather confers to these soils high vulnerability to abiotic stresses The diversification of production via adoption of integrated cropping-livestock-forestry (ICLF) systems is an important strategy to increase productivity and, simultaneously enhance ecosystem services. ICLF systems can increase carbon sequestration, conserve biodiversity and improve soil, water and air quality, compared with specialized production systems. Two trials were carried out for five years using ICLF in Santo Inácio county in Paraná state, Brazil. In the first three years, it was possible to harmonize production of grains (soybean), fodder (Brachiaria ruziziensis and brizantha) and wood (Eucalyptus) without negative effects of three components on each other. After the third year, the trees significantly reduced grain yield and fodder production, indicating the need for thinning to reduce tree interference. The ICLF system is relevant to increase the delivery of ecosystem goods and services in Northwestern Paraná, though technological adjustments are needed to increase its economic and environmental gains.

Biocarvão no solo: aspectos agronômicos e ambientais.

Embora a prática do uso do carvão vegetal no solo visando a melhoria do desenvolvimento das plantas seja milenar, pouco se sabe sobre os efeitos técnicos de sua aplicação, sobretudo em longo prazo. Assim, tendo as terras pretas de índio (TPIs) como modelo de sustentabilidade do solo em função da presença de carbono pirogênico (C-pyr), na última década os estudos acerca do uso de materiais ricos nessa forma de carbono (biocarvão) se intensificaram. Diversos estudos têm abordado os efeitos da aplicação de biocarvão no solo e seus efeitos sobre os atributos físicos, químicos e biológicos do solo, sobre a matéria orgânica, ciclos biogeoquímicos do carbono, desempenho agronômico de culturas anuais, espécies florestais, olerículas, emissão de gases de efeito estufa (N2O, CO2 e CH4) e mais recentemente os efeitos sobre a dinâmica de pesticidas no solo. Nesse sentido, esse trabalho aborda algumas características do uso do biocarvão no solo, com enfoque na sua produção, matéria prima, características físicas e químicas, aspectos agronômicos e ambientais do uso em solos e como substratos agrícolas.

Beyond conservation agriculture.

ABSTRACT: Global support for Conservation Agriculture (CA) as a pathway to Sustainable Intensification is strong. CA revolves around three principles: no-till (or minimal soil disturbance), soil cover, and crop rotation. The benefits arising from the ease of crop management, energy/cost/time savings, and soil and water conservation led to widespread adoption of CA, particularly on large farms in the Americas and Australia, where farmers harness the tools of modern science: highly-sophisticated machines, potent agrochemicals, and biotechnology. Over the past 10 years CA has been promoted among smallholder farmers in the (sub-) tropics, often with disappointing results. Growing evidence challenges the claims that CA increases crop yields and builds-up soil carbon although increased stability of crop yields in dry climates is evident. Our analyses suggest pragmatic adoption on larger mechanized farms, and limited uptake of CA by smallholder farmers in developing countries. We propose a rigorous, context-sensitive approach based on Systems Agronomy to analyze and explore sustainable intensification options, including the potential of CA. There is an urgent need to move beyond dogma and prescriptive approaches to provide soil and crop management options for farmers to enable the Sustainable Intensification of agriculture.

MAGGnet: an international network to foster mitigation of agricultural greenhouse gases.

Research networks provide a framework for review, synthesis and systematic testing of theories by multiple scientists across international borders critical for addressing global-scale issues. In 2012, a GHG research network referred to as MAGGnet (Managing Agricultural Greenhouse Gases Network) was established within the Croplands Research Group of the Global Research Alliance on Agricultural Greenhouse Gases (GRA). With involvement from 46 alliance member countries, MAGGnet seeks to provide a platform for the inventory and analysis of agricultural GHG mitigation research throughout the world. To date, metadata from 315 experimental studies in 20 countries have been compiled using a standardized spreadsheet. Most studies were completed (74%) and conducted within a 1-3-year duration (68%). Soil carbon and nitrous oxide emissions were measured in over 80% of the studies. Among plant variables, grain yield was assessed across studies most frequently (56%), followed by stover (35%) and root (9%) biomass. MAGGnet has contributed to modeling efforts and has spurred other research groups in the GRA to collect experimental site metadata using an adapted spreadsheet. With continued growth and investment, MAGGnet will leverage limited-resource investments by any one country to produce an inclusive, globally shared meta-database focused on the science of GHG mitigation.

Monitoramento do estoque de carbono no solo no sistema de Integração Lavoura-Pecuária-Floresta em área de cerrado de Minas Gerais.

2016

Carbon in humic fractions of organic matter in soil treated with organic composts under mango cultivation.

Soil organic matter (SOM) plays a key role in maintaining the productivity of tropical soils, providing energy and substrate for the biological activity and modifying the physical and chemical characteristics that ensure the maintenance of soil quality and the sustainability of ecosystems. This study assessed the medium-term effect (six years) of the application of five organic composts, produced by combining different agro-industrial residues, on accumulation and chemical characteristics of soil organic matter. Treatments were applied in a long-term experiment of organic management of mango (OMM) initiated in 2005 with a randomized block design with four replications. Two external areas, one with conventional mango cultivation (CMM) and the other a fragment of regenerating Caatinga vegetation (RCF), were used as reference areas. Soil samples were collected in the three management systems from the 0.00-0.05, 0.05-0.10, and 0.10-0.20 m layers, and the total organic carbon content and chemical fractions of organic matter were evaluated by determining the C contents of humin and humic and fulvic acids. Organic compost application significantly increased the contents of total C and C in humic substances in the experimental plots, mainly in the surface layer. However, compost 3 (50 % coconut bagasse, 40 % goat manure, 10 % castor bean residues) significantly increased the level of the non-humic fraction, probably due to the higher contents of recalcitrant material in the initial composition. The highest increases from application of the composts were in the humin, followed by the fulvic fraction. Compost application increased the proportion of higher molecular weight components, indicating higher stability of the organic matter.

Carbon Stocks in Compartments of Soil Organic Matter 31 Years after Substitution of Native Cerrado Vegetation by Agroecosystems.

ABSTRACT: Changes in carbon stocks in different compartments of soil organic matter of a clayey Latossolo Vermelho Distrófico (Typic Haplustox), caused by the substitution of native savanna vegetation (cerrado sensu stricto) by agroecosystems, were assessed after 31 years of cultivation. Under native vegetation, a stock of 164.5 Mg ha-1 C was estimated in the 0.00-1.00 m layer. After 31 years of cultivation, these changes in soil C stocks were detected to a depth of 0.60 m. In the case of substitution of cerrado sensu stricto by no-tillage soybean-corn rotation, a reduction of at least 11 % of the soil C pools was observed. However, the adoption of no-tillage as an alternative to tillage with a moldboard plow (conventional system) reduced CO2 emissions by up to 12 %.

Relationships between labile soil organic carbon fractions under different soil management systems.

ABSTRACT: The study of labile carbon fractions (LCF) provides an understanding of the behavior of soil organic matter (SOM) under different soil management systems and cover crops. The aim of this study was to assess the effect of different soil management systems with respect to tillage, cover crop and phosphate fertilization on the amount of the LCF of SOM. Treatments consisted of conventional tillage (CT) and no-tillage (NT) with millet as the cover crop and a no-tillage system with velvet bean at two phosphorus dosages. Soil samples were collected and analyzed for organic carbon (OC), C oxidizable by KMnO4 (C-KMnO4), particulate OC (POC), microbial biomass carbon and light SOM in the 0.0-0.05, 0.05-0.10 and 0.10-0.20 m soil layers. The Carbon Management Index (CMI) was calculated to evaluate the impacts of soil management treatments on the quality of the SOM. The different LCFs are sensitive to different soil management systems, and there are significant correlations between them. C-KMnO4 is considered the best indicator of OC carbon lability. In the soil surface layers, the CT reduced the carbon content in all of the labile fractions of the SOM. The use of phosphorus led to the accumulation of OC and carbon in the different soil fractions regardless of the tillage system or cover crop. The application of phosphate fertilizer improved the ability of the NTsystem to promote soil quality, as assessed by the CMI.

Influence of Pseudomonas putida AF7 inoculation on soil enzymes.

There has been some concern about the environmental impact of microbial agents. Pseudomonas may be used as bioremediator and as biopesticide. In this study, we report the use of soil enzyme assays as biological indicator of possible negative effects in soil functioning after the P. putida AF7 inoculation. For that, P. putida AF7 was originally isolated from the rizosphere of rice and was inoculated on three soil types: Rhodic Hapludox (RH), Typic Hapludox (TH); and Arenic Hapludult (AH). The acid phosphatase, b-glucosidase and protease enzymes activities were measured for three period of evaluation (7, 14 and 21 days). In general, the enzymatic activities pre- sented variation among the tested soils. The highest activities of b-glucosidase and acid phosphatase were observed in the RH and AH soils, while the protease activity was higher in the TH soil. Also, the soil charac- teristics were measured for each plot. The activity of enzymes from the carbon cycle was positively correlated with the N and the P and the enzyme from the nitrogen cycle was negatively correlated with N and C.org. The presented data indicate that soil biochemical properties can be an useful tool for use as an indicator of soil perturba- tions by microbial inoculation in a risk assessment.