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Agronomy and Crop Sciences

Articles 1 - 11 of 11

Full-Text Articles in Terrestrial and Aquatic Ecology

A Regional Comparison Of Water Use Efficiency For Miscanthus, Switchgrass And Maize, Andy Vanloocke, Tracy E. Twine, Marcelo Zeri, Carl J. Bernacchi May 2015

A Regional Comparison Of Water Use Efficiency For Miscanthus, Switchgrass And Maize, Andy Vanloocke, Tracy E. Twine, Marcelo Zeri, Carl J. Bernacchi

Andy VanLoocke

The production of cellulosic feedstocks for renewable fuels will increase over the coming decades. However, it is uncertain which feedstocks will be best suited for bioenergy production. A key factor dictating feedstock selection for a given region is water use efficiency (WUE), the trade-off between evapotranspiration (ET) and carbon uptake or productivity. Using an ecosystem model, two of the top candidate cellulosic feedstocks, Miscanthus × giganteus (miscanthus) and Panicum virgatum(switchgrass) were compared to Zea mays L. (maize), the existing dominant bioenergy feedstock, with 0 and 25% residue removal for the Midwest US. We determined productivity in three ways: harvested yield …

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Future Carbon Dioxide Concentration Decreases Canopy Evapotranspiration And Soil Water Depletion By Field-Grown Maize, Mir Zaman Hussain, Andy Vanloocke, Matthew H. Siebers, Ursula M. Ruiz-Vera, R. J. Cody Markelz, Donald R. Ort, Carl J. Bernacchi May 2015

Future Carbon Dioxide Concentration Decreases Canopy Evapotranspiration And Soil Water Depletion By Field-Grown Maize, Mir Zaman Hussain, Andy Vanloocke, Matthew H. Siebers, Ursula M. Ruiz-Vera, R. J. Cody Markelz, Donald R. Ort, Carl J. Bernacchi

Andy VanLoocke

Maize, in rotation with soybean, forms the largest continuous ecosystem in temperate North America, therefore changes to the biosphere-atmosphere exchange of water vapor and energy of these crops are likely to have an impact on the Midwestern US climate and hydrological cycle. As a C4 crop, maize photosynthesis is already CO2-saturated at current CO2 concentrations ([CO2]) and the primary response of maize to elevated [CO2] is decreased stomatal conductance (gs). If maize photosynthesis is not stimulated in elevated [CO2], then reduced gs is not offset by greater canopy leaf area, which could potentially result in a greater ET reduction relative …

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Terrestrial Ecosystems In A Changing Environment: A Dominant Role For Water, Carl J. Bernacchi, Andy Vanloocke May 2015

Terrestrial Ecosystems In A Changing Environment: A Dominant Role For Water, Carl J. Bernacchi, Andy Vanloocke

Andy VanLoocke

Transpiration—the movement of water from the soil, through plants, and into the atmosphere—is the dominant water flux from the earth's terrestrial surface. The evolution of vascular plants, while increasing terrestrial primary productivity, led to higher transpiration rates and widespread alterations in the global climate system. Similarly, anthropogenic influences on transpiration rates are already influencing terrestrial hydrologic cycles, with an even greater potential for changes lying ahead. Intricate linkages among anthropogenic activities, terrestrial productivity, the hydrologic cycle, and global demand for ecosystem services will lead to increased pressures on ecosystem water demands. Here, we focus on identifying the key drivers of …

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The Biophysical Link Between Climate, Water, And Vegetation In Bioenergy Agro-Ecosystems, Justin E. Bagley, Sarah C. Davis, Matei Georgescu, Mir Zaman Hussain, Jesse Miller, Stephen W. Nesbitt, Andy Vanloocke, Carl J. Bernacchi May 2015

The Biophysical Link Between Climate, Water, And Vegetation In Bioenergy Agro-Ecosystems, Justin E. Bagley, Sarah C. Davis, Matei Georgescu, Mir Zaman Hussain, Jesse Miller, Stephen W. Nesbitt, Andy Vanloocke, Carl J. Bernacchi

Andy VanLoocke

Land use change for bioenergy feedstocks is likely to intensify as energy demand rises simultaneously with increased pressure to minimize greenhouse gas emissions. Initial assessments of the impact of adopting bioenergy crops as a significant energy source have largely focused on the potential for bioenergy agroecosystems to provide global-scale climate regulating ecosystem services via biogeochemical processes. Such as those processes associated with carbon uptake, conversion, and storage that have the potential to reduce global greenhouse gas emissions (GHG). However, the expansion of bioenergy crops can also lead to direct biophysical impacts on climate through water regulating services. Perturbations of processes …

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The Biophysical Link Between Climate, Water, And Vegetation In Bioenergy Agro-Ecosystems, Andy Vanloocke, Justin E. Bagley, Sarah C. Davis, Mir Zaman Hussain, Jesse Miller, Stephen W. Nesbitt, Carl J. Bernacchi Nov 2014

The Biophysical Link Between Climate, Water, And Vegetation In Bioenergy Agro-Ecosystems, Andy Vanloocke, Justin E. Bagley, Sarah C. Davis, Mir Zaman Hussain, Jesse Miller, Stephen W. Nesbitt, Carl J. Bernacchi

Andy VanLoocke

Land use change for bioenergy feedstocks is likely to intensify as energy demand rises simultaneously with increased pressure to minimize greenhouse gas emissions. Initial assessments of the impact of adopting bioenergy crops as a significant energy source have largely focused on the potential for bioenergy agroecosystems to provide global-scale climate regulating ecosystem services via biogeochemical processes. Such as those processes associated with carbon uptake, conversion, and storage that have the potential to reduce global greenhouse gas emissions (GHG). However, the expansion of bioenergy crops can also lead to direct biophysical impacts on climate through water regulating services. Perturbations of processes …

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Modelling C3 Photosynthesis From The Choroplast To The Ecosystem, Andy Vanloocke, Carl J. Bernacchi, Justin E. Bagley, Shawn P. Serbin, Ursula M. Ruiz-Vera, David M. Rosenthal Aug 2013

Modelling C3 Photosynthesis From The Choroplast To The Ecosystem, Andy Vanloocke, Carl J. Bernacchi, Justin E. Bagley, Shawn P. Serbin, Ursula M. Ruiz-Vera, David M. Rosenthal

Andy VanLoocke

Globally, photosynthesis accounts for the largest flux of CO2 from the atmosphere into ecosystems and is the driving process for terrestrial ecosystem function. The importance of accurate predictions of photosynthesis over a range of plant growth conditions led to the development of a C3 photosynthesis model by Farquhar, von Caemmerer & Berry that has become increasingly important as society places greater pressures on vegetation. The photosynthesis model has played a major role in defining the path towards scientific understanding of photosynthetic carbon uptake and the role of photosynthesis on regulating the earth's climate and biogeochemical systems. In this review, we …

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Future Carbon Dioxide Concentration Decreases Canopy Evapotranspiration And Soil Water Depletion By Field-Grown Maize, Andy Vanloocke, Mir Zaman Houssain, Matthew H. Siebers, Ursula M. Ruiz-Vera, R. J. Cody Markelz, Andrew D. B. Leakey, Donald R. Orr, Carl J. Bernacchi Apr 2013

Future Carbon Dioxide Concentration Decreases Canopy Evapotranspiration And Soil Water Depletion By Field-Grown Maize, Andy Vanloocke, Mir Zaman Houssain, Matthew H. Siebers, Ursula M. Ruiz-Vera, R. J. Cody Markelz, Andrew D. B. Leakey, Donald R. Orr, Carl J. Bernacchi

Andy VanLoocke

Maize, in rotation with soybean, forms the largest continuous ecosystem in temperate North America, therefore changes to the biosphere-atmosphere exchange of water vapor and energy of these crops are likely to have an impact on the Midwestern US climate and hydrological cycle. As a C4 crop, maize photosynthesis is already CO2-saturated at current CO2 concentrations ([CO2]) and the primary response of maize to elevated [CO2] is decreased stomatal conductance (gs). If maize photosynthesis is not stimulated in elevated [CO2], then reduced gs is not offset by greater canopy leaf area, which could potentially result in a greater ET reduction relative …

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A Regional Comparison Of Water Use Efficiency For Miscanthus, Switchgrass And Maize, Andy Vanloocke, Tracy E. Twine, Marcelo Zeri, Carl J. Bernacchi Sep 2012

A Regional Comparison Of Water Use Efficiency For Miscanthus, Switchgrass And Maize, Andy Vanloocke, Tracy E. Twine, Marcelo Zeri, Carl J. Bernacchi

Andy VanLoocke

The production of cellulosic feedstocks for renewable fuels will increase over the coming decades. However, it is uncertain which feedstocks will be best suited for bioenergy production. A key factor dictating feedstock selection for a given region is water use efficiency (WUE), the trade-off between evapotranspiration (ET) and carbon uptake or productivity. Using an ecosystem model, two of the top candidate cellulosic feedstocks, Miscanthus × giganteus (miscanthus) and Panicum virgatum (switchgrass) were compared to Zea mays L. (maize), the existing dominant bioenergy feedstock, with 0 and 25% residue removal for the Midwest US. We determined productivity in three ways: harvested …

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Rising Ozone Concentrations Decrease Soybean Evapotranspiration And Water Use Efficiency Whilst Increasing Canopy Temperature, Andy Vanloocke, Amy M. Betzelberger, Elizabeth A. Ainsworth, Carl J. Bernacchi Jun 2012

Rising Ozone Concentrations Decrease Soybean Evapotranspiration And Water Use Efficiency Whilst Increasing Canopy Temperature, Andy Vanloocke, Amy M. Betzelberger, Elizabeth A. Ainsworth, Carl J. Bernacchi

Andy VanLoocke

Here, we investigated the effects of increasing concentrations of ozone ([O3]) on soybean canopy-scale fluxes of heat and water vapor, as well as water use efficiency (WUE), at the Soybean Free Air Concentration Enrichment (SoyFACE) facility. Micrometeorological measurements were made to determine the net radiation (Rn), sensible heat flux (H), soil heat flux (G0) and latent heat flux (λET) of a commercial soybean (Glycine max) cultivar (Pioneer 93B15), exposed to a gradient of eight daytime average ozone concentrations ranging from approximately current (c. 40 ppb) to three times current (c. 120 ppb) levels. As [O3] increased, soybean canopy fluxes of …

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The Impacts Of Miscanthus×Giganteus Production On The Midwest Us Hydrologic Cycle, Andy Vanloocke, Carl J. Bernacchi, Tracy E. Twine Jul 2010

The Impacts Of Miscanthus×Giganteus Production On The Midwest Us Hydrologic Cycle, Andy Vanloocke, Carl J. Bernacchi, Tracy E. Twine

Andy VanLoocke

Perennial grasses are being considered as candidates for biofuel feedstocks to provide an alternative energy source to fossil fuels. Miscanthus×giganteus (miscanthus), in particular, is a grass that is predicted to provide more energy per sown area than corn ethanol and reduce net carbon dioxide emissions by increasing the storage of carbon belowground. Miscanthus uses more water than Zea mays (maize), mainly as a result of a longer growing season and higher productivity. Conversion of current land use for miscanthus production will likely disrupt regional hydrologic cycles, yet the magnitude, timing, and spatial distribution of effects are unknown. Here, we show …

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A Comparison Of Canopy Evapotranspiration For Maize And Two Perennial Grasses Identified As Potential Bioenergy Crops, Andy Vanloocke, George C. Hickman, Frank G. Dohleman, Carl J. Bernacchi Jul 2010

A Comparison Of Canopy Evapotranspiration For Maize And Two Perennial Grasses Identified As Potential Bioenergy Crops, Andy Vanloocke, George C. Hickman, Frank G. Dohleman, Carl J. Bernacchi

Andy VanLoocke

In the Midwestern US, perennial rhizomatous grasses (PRGs) are considered one of the most promising vegetation types to be used as a cellulosic feedstock for renewable energy production. The potential widespread use of biomass crops for renewable energy production has sparked numerous environmental concerns, including the impacts of land-use change on the hydrologic cycle. We predicted that total seasonal evapotranspiration (ET) would be higher for PRGs relative to maize resulting from higher leaf area and a prolonged growing season. We further predicted that, compared with maize, higher aboveground biomass associated with PRGs would offset the higher ET and increase water-use …

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