Carlos Eduardo Pellegrino Cerri

Tropical agriculture and global warming: impacts and mitigation options

O uso intensivo da terra invariavelmente causa efeitos negativos ao ambiente e producao agricola se praticas conservativas nao forem adotadas. Reducao na quantidade de materia orgânica do solo significa emissao de gases (principalmente CO2, CH4, N2O) para a atmosfera e aumento do aquecimento global. A sustentabilidade do solo e tambem afetada, uma vez que a qualidade da materia orgânica remanescente muda. Alteracoes podem ser verificadas, por exemplo, pela desagregacao do solo e mudanca na sua estrutura. As consequencias sao erosao, reducao na disponibilidade de nutrientes para as plantas e baixa capacidade de retencao de agua no solo. Estes e outros fatores refletem negativamente na produtivade das culturas e sustentabilidade do sistema solo-planta-atmosfera. Ao contrario, a adocao de boas praticas de manejo, tal como o sistema plantio direto, pode parcialmente reverter o processo, uma vez que objetiva o aumento das entradas de material orgânico no solo e/ou diminuicao das taxas de decomposicao da materia orgânica do solo.

A social and ecological assessment of tropical land uses at multiple scales: the Sustainable Amazon Network

Science has a critical role to play in guiding more sustainable development trajectories. Here, we present the Sustainable Amazon Network (Rede Amazônia Sustentável, RAS): a multidisciplinary research initiative involving more than 30 partner organizations working to assess both social and ecological dimensions of land-use sustainability in eastern Brazilian Amazonia. The research approach adopted by RAS offers three advantages for addressing land-use sustainability problems: (i) the collection of synchronized and co-located ecological and socioeconomic data across broad gradients of past and present human use; (ii) a nested sampling design to aid comparison of ecological and socioeconomic conditions associated with different land uses across local, landscape and regional scales; and (iii) a strong engagement with a wide variety of actors and non-research institutions. Here, we elaborate on these key features, and identify the ways in which RAS can help in highlighting those problems in most urgent need of attention, and in guiding improvements in land-use sustainability in Amazonia and elsewhere in the tropics. We also discuss some of the practical lessons, limitations and realities faced during the development of the RAS initiative so far.

Potencial de sequestro de carbono em diferentes biomas do Brasil

SUMMARY : POTENTIAL OF SOIL CARBON SEQUESTRATION INDIFFERENT BIOMES OF BRAZIL Soil is an important pool for C stocks and plays a fundamental role in greenhouse gasemissions and consequently in climatic changes. Land use change can cause either a negativeor a positive effect in terms of greenhouse gas emissions to the atmosphere. However, theintensification of global warming has been confirmed, related mainly to the increase ofgreenhouse gas emissions from burning of fossil fuel, deforestation, and adoption of inadequateagricultural land management practices. An inadequate soil use does not only contribute tointensified greenhouse effects but also creates problems related to soil sustainability due to thedegradation of soil organic matter, which negatively reflects on soil physical and chemicalattributes, as well as on its biodiversity. On the other hand, best management practices thatmaintain or even increase soil organic matter contents can minimize the effects of globalwarming. Examples of such management practices are no-tillage, rehabilitation of degradedpasture, reforestation of marginal lands and elimination of the burning activity among others.The aim of this review was to evaluate some of the main greenhouse gas sources related toagriculture and land use change, to present strategies to mitigate these emissions and to increaseC sequestration in the soil-plant system, in three of the main biomes of Brazil.Index terms: land use change, greenhouse gas emissions, soil carbon stocks, global warming.

Net greenhouse gas fluxes in Brazilian ethanol production systems

Biofuels are both a promising solution to global warming mitigation and a potential contributor to the problem. Several life cycle assessments of bioethanol have been conducted to address these questions. We performed a synthesis of the available data on Brazilian ethanol production focusing on greenhouse gas (GHG) emissions and carbon (C) sinks in the agricultural and industrial phases. Emissions of carbon dioxide (CO2) from fossil fuels, methane (CH4) and nitrous oxide (N2O) from sources commonly included in C footprints, such as fossil fuel usage, biomass burning, nitrogen fertilizer application, liming and litter decomposition were accounted for. In addition, black carbon (BC) emissions from burning biomass and soil C sequestration were included in the balance. Most of the annual emissions per hectare are in the agricultural phase, both in the burned system (2209 out of a total of 2398 kg Ceq), and in the unburned system (559 out of 748 kg Ceq). Although nitrogen fertilizer emissions are large, 111 kg Ceq ha−1 yr−1, the largest single source of emissions is biomass burning in the manual harvest system, with a large amount of both GHG (196 kg Ceq ha−1 yr−1). and BC (1536 kg Ceq ha−1 yr−1). Besides avoiding emissions from biomass burning, harvesting sugarcane mechanically without burning tends to increase soil C stocks, providing a C sink of 1500 kg C ha−1 yr−1 in the 30 cm layer. The data show a C output: input ratio of 1.4 for ethanol produced under the conventionally burned and manual harvest compared with 6.5 for the mechanized harvest without burning, signifying the importance of conservation agricultural systems in bioethanol feedstock production.

The Amazon Frontier of Land-Use Change: Croplands and Consequences for Greenhouse Gas Emissions

Abstract The Brazilian Amazon is one of the most rapidly developing agricultural frontiers in the world. The authors assess changes in cropland area and the intensification of cropping in the Brazilian agricultural frontier state of Mato Grosso using remote sensing and develop a greenhouse gas emissions budget. The most common type of intensification in this region is a shift from single- to double-cropping patterns and associated changes in management, including increased fertilization. Using the enhanced vegetation index (EVI) from the Moderate Resolution Imaging Spectroradiometer (MODIS) sensor, the authors created a green-leaf phenology for 2001–06 that was temporally smoothed with a wavelet filter. The wavelet-smoothed green-leaf phenology was analyzed to detect cropland areas and their cropping patterns. The authors document cropland extensification and double-cropping intensification validated with field data with 85% accuracy for detecting croplands and 64% and 89% accuracy for detecting single- a...

Nitrous oxide emissions in agricultural soils: a review

The greenhouse gases concentration in the atmosphere have significantly increased since the beginning of the Industrial Revolution. The most important greenhouse gases are CO 2 , CH 4 and N 2 O, with CH 4 and N 2 O presenting global warming potentials 25 and 298 times higher than CO 2 , respectively. Most of the N 2 O emissions take place in soils and are related with agricultural activities. So, this review article aimed at presenting the mechanisms of N 2 O formation and emission in agricultural soils, as well as gathering and discussing information on how soil management practices may be used to reduce such emissions. The N 2 O formation in the soil occurs mainly through nitrification and denitrification processes, which are influenced by soil moisture, temperature, oxygen concentration, amount of available organic carbon and nitrogen and soil C/N ratio. Among these factors, those related to soil could be easily altered by management practices. Therefore, understanding the processes of N 2 O formation in soils and the factors influencing these emissions is fundamental to develop efficient strategies to reduce N 2 O emissions in agricultural soils.

Acid rain and nitrogen deposition in a sub-tropical watershed (Piracicaba): ecosystem consequences.

High levels of wet N and acidic deposition were measured in southeast Brazil. In this study we addressed the sensitivity of water bodies and soils to acidification and N deposition in the Piracicaba River basin (12,400 km2). Average acid neutralization capacity (ANC) at 23 river sampling sites varied from 350 to 1800 microeq l(-1). Therefore, rivers and streams in the Piracicaba basin are well buffered, if the lower limit of 200 microeq l(-1) is assumed as an indication of poorly buffered waters. ANC is increased by untreated wastewaters discarded into rivers and streams of the region. Average NO3 concentrations varied from 20 to 70 microeq l(-1). At the most polluted river sites, NO3 concentration is not highest, however, probably due to NO3 reduction and denitrification. Most of the nitrogen in streams is also provided by wastewaters and not by wet deposition. The majority of the soils in the basin, however, are acidic with a low base cation content and high aluminum concentration. Therefore, soils in this basin are poorly buffered and, in areas of forest over sandy soils, acidification may be a problem.

Propriedades químicas de um Neossolo Quartzarênico sob diferentes sistemas de manejo no Cerrado mato-grossense

O objetivo deste trabalho foi avaliar o efeito de diferentes usos da terra e sistemas de manejo do solo, nas caracteristicas quimicas de um Neossolo Quartzarenico, no Cerrado de Mato Grosso. Os tratamentos estudados foram: cerrado nativo; uma pastagem de baixa produtividade com 22 anos de implantacao; plantio convencional com 1 e 4 anos de uso e diferentes sucessoes de culturas; e plantio direto com 5 anos de implantacao. Foram determinados os teores de carbono e nitrogenio, pH, acidez potencial, capacidade de troca de cations (CTC), fosforo disponivel, bases trocaveis e saturacao por bases do solo. Os valores mais baixos de pH, fosforo disponivel, potassio, calcio e magnesio foram observados nas areas sob cerrado e pastagem, e a menor concentracao de carbono no solo sob pastagem refletiu menor CTC do solo. A aplicacao do calcario nos tratamentos com plantio convencional e direto favorece o aumento das concentracoes de calcio e magnesio no solo. Nesses sistemas, a saturacao por bases (V%) do solo e mais elevada nas areas com maior tempo de implantacao (4 e 5 anos). Embora o Neossolo Quartzarenico possua limitacoes para o cultivo, em razao de sua baixa fertilidade natural, se adequadamente manejado, este solo apresenta potencial para o cultivo agricola.

Soil carbon stocks and changes after oil palm introduction in the Brazilian Amazon

As oil palm has been considered one of the most favorable oilseeds for biodiesel production in Brazil, it is important to understand how cultivation of this perennial crop will affect the dynamics of soil organic carbon (SOC) in the long term. The aim of this study was to evaluate the changes in soil C stocks after the conversion of forest and pasture into oil palm production in the Amazon Region. Soil samples were collected in March 2008 and September 2009 in five areas: native forest (NARF), pasture cultivated for 55 years (PAST), and oil palm cultivated for 4 (OP‐4), 8 (OP‐8) and 25 years (OP‐25), respectively. Soils were sampled in March 2008 to evaluate the spatial variability of SOC and nitrogen (N) contents in relation to the spacing between trees. In September 2009, soils were sampled to evaluate the soil C stocks in the avenues (inter rows) and frond piles, and to compare the total C stocks with natural forest and pasture system. Soil C contents were 22–38% higher in the area nearest the oil palm base (0.6 m) than the average across the inter row (0–4.5 m from the tree), indicating that the increment in soil organic matter (SOM) must have been largely derived from root material. The soil C stocks under palm frond piles were 9–26% higher than in the inter rows, due to inputs of SOM by pruned palm fronds. The soil carbon stocks in oil palm areas, after adjustments for differences in bulk density and clay content across treatments, were 35–46% lower than pasture soil C stocks, but were 0–18% higher than the native forest soil C content. The results found here may be used to improve the life cycle assessment of biodiesel derived from palm oil.

Greenhouse gas emissions from alternative futures of deforestation and agricultural management in the southern Amazon.

The Brazilian Amazon is one of the most rapidly developing agricultural areas in the world and represents a potentially large future source of greenhouse gases from land clearing and subsequent agricultural management. In an integrated approach, we estimate the greenhouse gas dynamics of natural ecosystems and agricultural ecosystems after clearing in the context of a future climate. We examine scenarios of deforestation and postclearing land use to estimate the future (2006–2050) impacts on carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) emissions from the agricultural frontier state of Mato Grosso, using a process-based biogeochemistry model, the Terrestrial Ecosystems Model (TEM). We estimate a net emission of greenhouse gases from Mato Grosso, ranging from 2.8 to 15.9 Pg CO2-equivalents (CO2-e) from 2006 to 2050. Deforestation is the largest source of greenhouse gas emissions over this period, but land uses following clearing account for a substantial portion (24–49%) of the net greenhouse gas budget. Due to land-cover and land-use change, there is a small foregone carbon sequestration of 0.2–0.4 Pg CO2-e by natural forests and cerrado between 2006 and 2050. Both deforestation and future land-use management play important roles in the net greenhouse gas emissions of this frontier, suggesting that both should be considered in emissions policies. We find that avoided deforestation remains the best strategy for minimizing future greenhouse gas emissions from Mato Grosso.