Temporal Variability of Soil CO2 Emission Contrasting Degraded and Managed Pasture in Brazil

AbstractGrazing areas represent the largest agricultural areas in Brazil, occupying more than 172 million hectares, about 20% of the agricultural land (IBGE, 2007). Despite the large areas of degraded pasture, little information exists about the temporal variation of soil properties including nutrients and soil carbon dynamic (Cerri et al., 2004). This study aimed to measure soil FCO2 from degraded and managed pasture areas, describing their temporal variability correlated to the environmental variables. Our study was carried out at two pasture areas located in Mococa city, São Paulo State Brazil. On March 04, 2013, 2 grids of 100 × 100 m with 102 samples points were installed in DP (Degraded pasture) and managed pasture (MP). Measurements of soil CO2 emissions (FCO2), soil temperature (Tsoil) and water content of soil (WCsoil) were initiated onMarch 12th, resulting 8 measuring days. Higher difference of emission between both areasoccurred during the first days, probably due to a huge precipitation influence (accumulated 80mm). In the first study day (12th), emission values were 8.73 ± 0.38 versus 4.47 ± 0.21μmol m-2 s-1, in DP and MP, respectively. In the last study day, March 19th, emissions in both areas were closer without remarkable rain influence (7.43 ± 0.54 and 5.98 ± 0.17μmol m-2 s-1). Total emission calculated by the area bellow the emission curves resulted 640.7 versus 440.0kg CO2-C ha-1 in DP and MP, respectively, corresponding to an additional emission of 200.6kg CO2-C ha-1 from DP or, 735.5kg CO2 released to the atmosphere, contributing to the Climate Change. The potential for soil C sequestration in pasture soils is strictly related to their management, and the rate and mechanism of soil C losses in pasture soils can affect this potential, with soils functioning as an atmospheric CO2 sinking or emitter

Greenhouse gas emission associated with sugar production in southern Brazil

<p>Abstract</p> <p>Background</p> <p>Since sugarcane areas have increased rapidly in Brazil, the contribution of the sugarcane production, and, especially, of the sugarcane harvest system to the greenhouse gas emissions of the country is an issue of national concern. Here we analyze some data characterizing various activities of two sugarcane mills during the harvest period of 2006-2007 and quantify the carbon footprint of sugar production.</p> <p>Results</p> <p>According to our calculations, 241 kg of carbon dioxide equivalent were released to the atmosphere per a ton of sugar produced (2406 kg of carbon dioxide equivalent per a hectare of the cropped area, and 26.5 kg of carbon dioxide equivalent per a ton of sugarcane processed). The major part of the total emission (44%) resulted from residues burning; about 20% resulted from the use of synthetic fertilizers, and about 18% from fossil fuel combustion.</p> <p>Conclusions</p> <p>The results of this study suggest that the most important reduction in greenhouse gas emissions from sugarcane areas could be achieved by switching to a green harvest system, that is, to harvesting without burning.</p

Greenhouse gas balance due to the conversion of sugarcane areas from burned to green harvest in Brazil

Strategies for the reduction of greenhouse gas emission in agriculture have been debated for some time, especially in Brazil, where the agricultural sector is an important contributor to the national emission balance. The present study focuses on the change in greenhouse gas balance from the conversion of sugarcane areas from burned to green harvest, considering both agricultural and mobile sources. The results are presented in terms of CO(2) equivalent, using the gases CO(2), CH(4) and N(2)O, and indicate that N synthetic fertilizer and burning of residues are responsible for the higher emissions observed in green and burned areas, with 1167.6 and 941.0 kg CO(2)equiv.ha(-1) y(-1), respectively. The sugarcane burning plot presented the highest emissions in our scope, with 3103.9 kg CO(2)equiv.ha(-1) y(-1). Our estimates indicate that conversion from burned to green plot could save from 310.7 (not considering soil carbon sequestration) to 1484.0 kg CO(2)equiv.ha(-1) y(-1) (considering soil carbon sequestration). The development of ethanol and sugar production in Brazil should certainly move towards the reduction of burning practice and diesel use, avoiding some tillage operations and should also adopt more efficient fertilization practices to reduce N fertilizer inputs, attaining reduction in greenhouse gas emissions from the sugarcane agricultural sector. (C) 2011 Elsevier B.V. All rights reserved.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES

Greenhouse gas emissions and offset potential from sugarcane straw for bioenergy production in Brazil

This study aims to assess the additional Greenhouse gas (GHG) emissions affected by straw removal from the soil surface in sugarcane areas, including measurement of short-term soil CO2-C emissions plus emissions associated with the recovery and transport operations of straw bales until to the industry gate (diesel emissions) and estimated soil N2O emission, comparing with leaving all straw on the soil surface. Taking into account the main sources evaluated (soil CO2, diesel and N2O from straw), the total additional GHG emissions from the recovery of 6.9 Mg Dry Matter ha-1 (27%) was estimated at 1423 kg CO2eq ha-1, resulting in a carbon footprint of 206.2 kg CO2eq per megagram (Mg) of straw recovered. Applying the parameters cited in this study for electricity generation (GHG emission and offset potential), our results showed an additional GHG emission of (+) 860 kg CO2eq ha-1. Applying the same parameters for second generation (2G) ethanol production replacing gasoline, an avoided GHG emission of (-) 2316 kg CO2eq ha-1 could be achieved. The route of recovering 27% of sugarcane straw from the soil surface through bale system for bioelectricity production using the technical parameters and industrial efficiency rate of this case study resulted in a C footprint of 347 kg CO2eq MWh-1. Improving the efficiency rate for straw conversion in bioelectricity based on its lower heating value could reduce its C footprint to 62.26 kg CO2eq MWh-1 produced. For sugarcane straw recovery at the first cutting cycle in clay soil, the option of producing ethanol 2G could offset GHG emissions once replacing fossil gasoline, resulting in a C footprint of 0.86 kg CO2eq L-1 of 2G ethanol in the agricultural phase, an option to contribute to better sustainability of sugarcane straw recovery, supporting renewable and sustainable bioenergy systems, and reducing the impacts of Global Climate Change

Sustainability of sugarcane production in Brazil. A review

International audienceAbstractBrazil is a major sugarcane producer and its production more than doubled over the last decades to meet global bioenergy demands for reducing crude oil dependency and mitigating climate change. Nevertheless, the adverse effects of this growth on jeopardizing the sustainability of sugarcane production are not known, especially when environmental impacts of agricultural inputs and production processes are not judiciously managed. This article is a comprehensive review of the state-of-the-knowledge and the main advances made thus far in the sugarcane sector. Here, we review the major environmental impacts of rapidly expanding sugarcane plantation on the land use change and its competition with food production, as well as those associated with sugarcane cultivation in Brazil. Our main finding are that sugarcane plantation did not contribute to direct deforestation, and its expansion on degraded pastures with the attendant increased yields of food crops and livestock intensification decreased land competition between food and sugarcane. Non-burning sugarcane harvesting is a win-win strategy because of its benefits involving agronomic and environmental aspects, but soil compaction is among the main issues in sugarcane cropping systems. Sugarcane is highly efficient in terms of nitrogen use efficiency, which is an important factor for its high energy balance. But, special attention should be given regarding emissions of nitrous oxide when straw mulching is combined with application of nitrogen fertilizer and vinasse. Recent advances in the sugarcane sector also show significant reductions in water consumption, making sugarcane ethanol one of the most favorable options in terms of water footprint. Growing realization of a vast potential indicates the need to further enhance the environmental benefits of sugarcane ethanol by optimizing the agricultural production chain. Based on this improved knowledge, the adoption of best management practices is among researchable priorities that can be developed to consolidate the large potential of sugarcane production towards greater sustainability

Greenhouse gas mitigation potential from green harvested sugarcane scenarios in São Paulo State, Brazil

Brazil is a major sugarcane producer and São Paulo State cultivates 5.5 million hectares, close to 50% of Brazil's sugarcane area. The rapid increase in production has brought into question the sustainability of biofuels, especially considering the greenhouse gas (GHG) emissions associated to the agricultural sector. Despite the significant progress towards the green harvest practices, 1.67 million hectares were still burned in São Paulo State during the 2011 harvest season. Here an emissions inventory for the life cycle of sugarcane agricultural production is estimated using IPCC methodologies, according to the agriculture survey data and remote sensing database. Our hypothesis is that 1.67 million hectares shall be converted from burned to green harvest scenarios up to years 2021 (rate 1), 2014 (rate 2) or 2029 (rate 3). Those conversions would represent a significant GHG mitigation, ranging from 50.5 to 70.9 megatons of carbon dioxide equivalent (Mt CO2eq) up to 2050, depending on the conversion rate and the green harvest systems adopted: conventional (scenario S1) or conservationist management (scenario S2). We show that a green harvest scenario where crop rotation and reduced soil tillage are practiced has a higher mitigation potential (70.9 Mt CO2eq), which is already practiced in some of the sugarcane areas. Here we support the decision to not just stop burning prior to harvest, but also to consider other better practices in sugarcane areas to have a more sustainable sugarcane based ethanol production in the most dense cultivated sugarcane region in Brazil. © 2013 Elsevier Ltd. All rights reserved