968 resultados para soil depth change


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Includes bibliography

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Climate change is anticipated to have potentially disastrous impacts on the economic viability of the agricultural sector, insomuch as traditional agricultural practices render the agricultural sector climate-dependent. Increased temperatures and increased intensity, timing and occurrence of hydro events are expected to challenge plant and animal viability. Under such circumstances, vector control is expected to become more difficult, which may further prejudice the prosperity of plant, livestock and fisheries growth. The impact is expected to be on the quality of agricultural produce and thereby, indirectly, on human health outcomes. The key threat mechanisms are debilitated plant vitality and increased propagation of pests, as drought periods increase the breeding of vectors through water pooling and soil erosion associated with the increased intensity of hydro events. In addition, climate change is likely to affect crop productivity in specific geographical areas through its impact on growing seasons and crop patterns, to the extent that crop varieties cannot adapt.

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The economic impact of climate change on root crop, fisheries and vegetable production for Trinidad and Tobago under the A2 and B2 scenarios were modeled, relative to a baseline ―no climate change‖ case, where the mean temperature and rainfall for a base period of 1980 – 2000 was assumed for the years up to 2050. Production functions were used, using ARMA specifications to correct for serial autocorrelation. For the A2 scenarios, rainfall is expected to fall by approximately 10% relative to the baseline case in the 2020s, but is expected to rise thereafter, until by the 2040s rainfall rises slightly above the mean for the baseline case. For the B2 scenario, rainfall rose slightly above the mean for the baseline case in the current decade, but falls steadily thereafter to approximately 15% by the 2040s. Over the same period, temperature is expected to increase by 1.34C and 1.37C under A2 and B2 respectively. It is expected that any further increase in rainfall should have a deleterious effect on root crop production as a whole, since the above mentioned crops represent the majority of the root crops included in the study. Further expected increases in temperature will result in the ambient temperature being very close to the optimal end of the range for most of these crops. By 2050, the value of yield cumulative losses (2008$) for root crops is expected to be approximately 248.8 million USD under the A2 scenario and approximately 239.4 million USD under the B2 scenario. Relative to the 2005 catch for fish, there will be a decrease in catch potential of 10 - 20% by 2050 relative to 2005 catch potentials, other things remaining constant. By 2050 under the A2 and B2 scenarios, losses in real terms were estimated to be 160.2 million USD and 80.1 million USD respectively, at a 1% discount rate. For vegetables, the mean rainfall exceeds the optimal rainfall range for sweet peppers, hot peppers and melongene. However, while the optimal rainfall level for tomatoes is 3000mm/yr, other vegetables such as sweet peppers, hot peppers and ochroes have very low rainfall requirements (as low as 300 mm/yr). Therefore it is expected that any further decrease in rainfall should have a mixed effect on individual vegetable production. It is expected that any further increase in temperature should have a mixed effect on individual vegetable production, though model results indicated that as a group, an increase in temperature should have a positive impact on vegetable production. By 2050, the value of yield cumulative gains (2008$) for vegetables is expected to be approximately 54.9 million USD under the A2 scenario and approximately 49.1 million USD under the B2 scenario, given a 1% discount rate. For root crops, fisheries and vegetables combined, the cumulative loss under A2 is calculated as approximately 352.8 million USD and approximately 270.8 million USD under B2 by 2050. This is equivalent to 1.37% and 1.05% of the 2008 GDP under the A2 and B2 scenarios respectively by 2050. Sea Level Rise (SLR) by 2050 is estimated to be 0.255 m under A2 and 0.215 m under B2. GIS estimation indicated that for a 0.255 m sea level rise, combined with a 0.5 m high tide, there would be no permanent inundation of agricultural land in Trinidad. The total inundation area is 1.18 km2. This occurs only in the Caroni Watershed, on the western coast of Trinidad, and the areas are outside the Caroni Swamp. Even with an additional rise of 0.5 m to simulate a high rainfall event, the estimated inundated area is 4.67 km2, but with no permanent inundation, though likely to be subject to flooding. Based on eleven (11) evaluation criteria, the top potential adaptation options were identified: 1. Use of water saving irrigation systems and water management systems e.g. drip irrigation; 2. Mainstream climate change issues into agricultural management; 3. Repair/maintain existing dams; 4. Alter crop calendar for short-term crops; 5. Adopt improved technologies for soil conservation; 6. Establish systems of food storage; 7. Promote water conservation – install on-farm water harvesting off roof tops; 8. Design and implement holistic water management plans for all competing uses; 9. Build on- farm water storage (ponds and tanks); 10. Agricultural drainage; and 11. Installation of greenhouses. The most attractive adaptation options, based on the Benefit-Cost Ratio are: (1) Build on- farm water storage such as ponds and tanks (2) Mainstreaming climate change issues into agricultural management and (3) Water Harvesting. However, the options with the highest net benefits are, (in order of priority): (1) Build on- farm water storage such as ponds and tanks, (2) Mainstreaming climate change issues into agricultural management and (3) Use of drip irrigation. Based on the area burnt in Trinidad and Tobago between 2005 and 2009, the average annual loss due to fires is 1717.3 ha. At US$17.41 per carbon credit, this implies that for the total land lost to forest fires on average each year, the opportunity cost of carbon credit revenue is 74.3 million USD. If a teak reforestation programme is undertaken in Trinidad and Tobago, the net benefit of reforestation under a carbon credit programme would be 69 million USD cumulatively to 2050.

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Soil physical quality is an important factor for the sustainability of agricultural systems. Thus, the aim of this study was to evaluate soil physical properties and soil organic carbon in a Typic Acrudox under an integrated crop-livestock-forest system. The experiment was carried out in Mato Grosso do Sul, Brazil. Treatments consisted of seven systems: integrated crop-livestock-forest, with 357 trees ha-1 and pasture height of 30 cm (CLF357-30); integrated crop-livestock-forest with 357 trees ha-1 and pasture height of 45 cm (CLF357-45); integrated crop-livestock-forest with 227 trees ha-1 and pasture height of 30 cm (CLF227-30); integrated crop-livestock-forest with 227 trees ha-1 and pasture height of 45 cm (CLF227-45); integrated crop-livestock with pasture height of 30 cm (CL30); integrated crop-livestock with pasture height of 45 cm (CL45) and native vegetation (NV). Soil properties were evaluated for the depths of 0-10 and 10-20 cm. All grazing treatments increased bulk density (r b) and penetration resistance (PR), and decreased total porosity (¦t) and macroporosity (¦ma), compared to NV. The values of r b (1.18-1.47 Mg m-3), ¦ma (0.14-0.17 m³ m-3) and PR (0.62-0.81 MPa) at the 0-10 cm depth were not restrictive to plant growth. The change in land use from NV to CL or CLF decreased soil organic carbon (SOC) and the soil organic carbon pool (SOCpool). All grazing treatments had a similar SOCpool at the 0-10 cm depth and were lower than that for NV (17.58 Mg ha-1).

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Because the agricultural use of tannery sludge may cause increased risks to soils, composting is recognized as one of the most suitable alternative for tannery sludge recycling. Experiments were conducted under field conditions to evaluate the effects of composted tannery sludge (CTS) on the soil microbial biomass and trace elements after two years of consecutive applications. The following five treatments were used: 0 (without CTS application), 5, 10, 20 and 40 ton ha-1 of CTS (dry basis). Soil samples were collected at 60 days after the CTS application at 0-20 cm depth. The CTS application promoted changes in the soil microbial biomass C (SMB-C) and N (SMB-N). In the first year, significant increases in the SMB-C and SMB-N were observed with the application of 10 ton ha-1. Furthermore, CTS application increased the Cr content in the soil after two years of application.

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The tillage comprises on average 25% of the cost of deploying a reed, so this cost reduction measures are desirable since they do not compromise the quality of the operation and longevity of sugarcane. The objective was to evaluate the effect of different tillage systems in Acrustox, correlating soil physical properties and characteristics of sugarcane agroindustrial plant cane and ratoon cane. We used five types of soil tillage, over experimental design in blocks with five replications. The particle size was measured every 0.1 m to 0.4 m depth, through deformed soil samples collected at the end of the first growth cycle of the culture. For other soil physical properties: bulk density, total porosity and water content, assessments were performed at the end of each cycle, collecting soil samples in layers of 0-0.20 to 0.21-0.40 m, in addition to performing the penetration resistance, using a penetrometer impact. The response of sugarcane depending on the types of tillage was determined from the evaluation of productivity per hectare of stem (TCH), sugar (TPH), the values of pol % cane (AP), sugar total recoverable (ATR) and fiber samples collected at harvest stalk of sugarcane plant and ratoon cane. In the tillage studied, there was a change of the physical attributes of the soil, causing reduced productivity in 2009/2010 crop, compared with the 2008/2009 season. In tillage system of furrowing direct lowest result was observed for TCH, especially in 2009/2010 crop, when the difference with conventional tillage was 20.53 Mg ha(-1).

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)