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Edmundo Barrios - One of the best experts on this subject based on the ideXlab platform.
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agroforestry boosts soil health in the Humid and sub Humid Tropics a meta analysis
Agriculture Ecosystems & Environment, 2020Co-Authors: Mary Nyawira Muchane, Gudeta W Sileshi, Sofia Gripenberg, Mattias Jonsson, Lorena Pumarino, Edmundo BarriosAbstract:Agroforestry has been increasingly recognized as a key example of agroecological praxis contributing to the sustainable intensification of food production while providing a number of additional benefits to society. However, a quantitative synthesis of the impact of agroforestry on soil health and associated ecosystem services in the Humid and sub-Humid Tropics is still lacking. The objective of this study was to quantify the contribution of agroforestry practices to soil-mediated ecosystem services, specifically, regulation of soil erosion, storage of soil organic carbon (SOC) and nitrogen (N), availability of soil N and phosphorus (P) to crops, and alleviation of soil acidity across the Humid and sub-Humid Tropics. The analysis demonstrated that agroforestry can reduce soil erosion rates by 50 % compared to crop monocultures. This finding is supported by higher infiltration rates, lower runoff, higher proportion of soil macroggregates, and greater stability of soil structure under agroforestry. SOC increased by 21 %, N storage increased by 13 %, available N by 46 % and available P by 11 % while soil pH increased by 2% under agroforestry compared to crop monocultures. We conclude that agroforestry can make significant contributions to provision of soil-mediated ecosystem services in the Humid and sub-Humid Tropics.
Gudeta W Sileshi - One of the best experts on this subject based on the ideXlab platform.
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agroforestry boosts soil health in the Humid and sub Humid Tropics a meta analysis
Agriculture Ecosystems & Environment, 2020Co-Authors: Mary Nyawira Muchane, Gudeta W Sileshi, Sofia Gripenberg, Mattias Jonsson, Lorena Pumarino, Edmundo BarriosAbstract:Agroforestry has been increasingly recognized as a key example of agroecological praxis contributing to the sustainable intensification of food production while providing a number of additional benefits to society. However, a quantitative synthesis of the impact of agroforestry on soil health and associated ecosystem services in the Humid and sub-Humid Tropics is still lacking. The objective of this study was to quantify the contribution of agroforestry practices to soil-mediated ecosystem services, specifically, regulation of soil erosion, storage of soil organic carbon (SOC) and nitrogen (N), availability of soil N and phosphorus (P) to crops, and alleviation of soil acidity across the Humid and sub-Humid Tropics. The analysis demonstrated that agroforestry can reduce soil erosion rates by 50 % compared to crop monocultures. This finding is supported by higher infiltration rates, lower runoff, higher proportion of soil macroggregates, and greater stability of soil structure under agroforestry. SOC increased by 21 %, N storage increased by 13 %, available N by 46 % and available P by 11 % while soil pH increased by 2% under agroforestry compared to crop monocultures. We conclude that agroforestry can make significant contributions to provision of soil-mediated ecosystem services in the Humid and sub-Humid Tropics.
Cheryl A Palm - One of the best experts on this subject based on the ideXlab platform.
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potential of agroforestry for carbon sequestration and mitigation of greenhouse gas emissions from soils in the Tropics
Nutrient Cycling in Agroecosystems, 2005Co-Authors: Georg Cadisch, Cheryl A Palm, Patrick Mutuo, Alai Albrech, Louis V VerchoAbstract:Losses of carbon (C) stocks in terrestrial ecosystems and increasing concentrations of greenhouse gases in the atmosphere are challenges that scientists and policy makers have been facing in the recent past. Intensified agricultural practices lead to a reduction in ecosystem carbon stocks, mainly due to removal of aboveground biomass as harvest and loss of carbon as CO2 through burning and/or decomposition. Evidence is emerging that agroforestry systems are promising management practices to increase aboveground and soil C stocks and reduce soil degradation, as well as to mitigate greenhouse gas emissions. In the Humid Tropics, the potential of agroforestry (tree-based) systems to sequester C in vegetation can be over 70 Mg C ha−1, and up to 25 Mg ha−1 in the top 20 cm of soil. In degraded soils of the sub-Humid Tropics, improved fallow agroforestry practices have been found to increase top soil C stocks up to 1.6 Mg C ha−1 y−1 above continuous maize cropping. Soil C accretion is linked to the structural development of the soil, in particular to increasing C in water stable aggregates (WSA). A review of agroforestry practices in the Humid Tropics showed that these systems were able to mitigate N2O and CO2 emissions from soils and increase the CH4 sink strength compared to cropping systems. The increase in N2O and CO2 emissions after addition of legume residues in improved fallow systems in the sub-Humid Tropics indicates the importance of using lower quality organic inputs and increasing nutrient use efficiency to derive more direct and indirect benefits from the system. In summary, these examples provide evidence of several pathways by which agroforestry systems can increase C sequestration and reduce greenhouse gas emissions.
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mitigating ghg emissions in the Humid Tropics case studies from the alternatives to slash and burn program asb
Environment Development and Sustainability, 2004Co-Authors: Cheryl A Palm, Meine Van Noordwijk, Thomas P Tomich, Steve Vosti, James Gockowski, Julio Alegre, Lou VerchotAbstract:Tropical forest conversion contributes as much as 25% of the net annual CO2 emissions and up to 10% of the N2O emissions to the atmosphere. The net effect on global warming potential (GWP) also depends on the net fluxes of greenhouse gases from land-use systems following deforestation. Efforts to mitigate these effects must take into account not only the greenhouse gas fluxes of alternative land-use systems but also the social and economic consequences that influence their widespread adoption. The global alternatives to slash-and-burn program (ASB) investigated the net greenhouse gas emissions and profitability of a range of land-use alternatives in the Humid Tropics. The analysis showed that many tree-based systems reduced net GWP compared to annual cropping and pasture systems. Some of these systems are also profitable in terms of returns to land and labor. The widespread adoption of these systems, however, can be limited by start-up costs, credit limitations, and number of years to positive cash flow, in addition to the higher labor requirements. Projects that offset carbon emissions through carbon sinks in land use in the Tropics might be a means of overcoming these limitations. A synthesis of the findings from this program can provide guidelines for the selection and promotion of land-use practices that minimize net global warming effects of slash-and-burn.
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agroforestry in acid soils of the Humid Tropics
Advances in Agronomy, 1991Co-Authors: L T Szott, Cheryl A Palm, Pedro A SanchezAbstract:Publisher Summary The majority of the soils in the Humid Tropics are acidic and infertile. Agroforestry systems are the most appropriate forms of sustainable, productive management of soils in the Humid Tropics because perennial woody vegetation can recycle nutrients, maintain soil organic matter, and protect the soil from surface erosion and runoff. This chapter evaluates three agroforestry systems that are helpful to overcome these constraints to production—namely, alley cropping systems; managed leguminous fallows to accelerate the restoration of soil fertility and reduce the duration of the fallow period; and fruit tree-annual crop sequential cropping systems. These technologies represent a range of agroforestry options, the suitability of which will vary with the relative availabilities of land, labor, and capital. Alley cropping may contribute to the maintenance of soil fertility under annual cropping by improved nutrient cycling, but the system's total labor and possibly capital requirements are likely to be greater than those with shifting cultivation. Hence, the system seems appropriate for situations of limited land availability. In contrast, managed fallows might reduce the duration of the fallow period and improve productivity per unit time by accelerating weed suppression and nutrient accumulation in the fallow biomass. This system requires relatively small quantities of labor and capital, but like most fallow-based systems, it requires moderate to high land availability. Finally, cultivation of fruit trees can help alleviate labor and capital constraints by spreading labor over periods of low demand and by providing additional income through the sale of fruits and other products.
Pedro A Sanchez - One of the best experts on this subject based on the ideXlab platform.
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agroforestry in acid soils of the Humid Tropics
Advances in Agronomy, 1991Co-Authors: L T Szott, Cheryl A Palm, Pedro A SanchezAbstract:Publisher Summary The majority of the soils in the Humid Tropics are acidic and infertile. Agroforestry systems are the most appropriate forms of sustainable, productive management of soils in the Humid Tropics because perennial woody vegetation can recycle nutrients, maintain soil organic matter, and protect the soil from surface erosion and runoff. This chapter evaluates three agroforestry systems that are helpful to overcome these constraints to production—namely, alley cropping systems; managed leguminous fallows to accelerate the restoration of soil fertility and reduce the duration of the fallow period; and fruit tree-annual crop sequential cropping systems. These technologies represent a range of agroforestry options, the suitability of which will vary with the relative availabilities of land, labor, and capital. Alley cropping may contribute to the maintenance of soil fertility under annual cropping by improved nutrient cycling, but the system's total labor and possibly capital requirements are likely to be greater than those with shifting cultivation. Hence, the system seems appropriate for situations of limited land availability. In contrast, managed fallows might reduce the duration of the fallow period and improve productivity per unit time by accelerating weed suppression and nutrient accumulation in the fallow biomass. This system requires relatively small quantities of labor and capital, but like most fallow-based systems, it requires moderate to high land availability. Finally, cultivation of fruit trees can help alleviate labor and capital constraints by spreading labor over periods of low demand and by providing additional income through the sale of fruits and other products.
Catherine Hénault - One of the best experts on this subject based on the ideXlab platform.
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Hydrology of a forested riparian zone in an agricultural landscape of the Humid Tropics
Agriculture Ecosystems and Environment, 2013Co-Authors: Sarah Connor, Paul N. Nelson, John David Armour, Catherine HénaultAbstract:Forested riparian zones are known to reduce movement of nitrogen from farms into streams in temperate areas, but predictive models of nitrogen transport and transformations rely on hydrological understanding, which is limited in the Humid Tropics. As a first step to understanding nitrogen cycling in the forested riparian zone of a lowland Humid tropical agricultural landscape, we studied the hydrology of a riparian site in northeast Australia. The site has undulating topography and a 150-m wide strip of relatively undisturbed forest between sugarcane fields and the perennial stream. Riparian hydrology was dynamic in the wet season with frequent interactions between ground and surface water. Vertical and lateral fluxes of water through the variably saturated zone were high during the wet season due to intense rainfall, permeable soils and a variable discharge zone. However, complete saturation was never observed in the variably saturated zone. During the dry season groundwater movement was slow and the water table was several metres deep throughout most of the site. Uptake of groundwater by vegetation was a significant component of the water balance during the dry season and groundwater discharge to the creek is likely to be negligible at this time. During the wet season, uptake was small relative to other fluxes and the transpiration requirements of the trees could be met by the topsoil for much of the time. The hydrological conditions encountered are likely to exert large and variable influences on the transport and transformations of nitrogen in this part of the landscape. Contrary to the common understanding of riparian zone function, it appears that riparian zones of Humid tropical lowlands are likely to be ineffective at removing nitrogen from groundwater. This will have implications for downstream water quality and ultimately on the quality of water discharging into the Great Barrier Reef lagoon, a sensitive and vulnerable marine environment.