Progress 09/01/09 to 08/31/11
Outputs
OUTPUTS: This will be a final report, however Hatch project WIS01586 will continue the work that is discussed within this report. Field measurements focused on carbon, water, and energy exchange in corn, switchgrass, and hybrid poplar bioenergy cropping systems. A suite of biophysical, ecological, and biogeochemical measurements began during the 2009 field season and continued through 2011 at the Great Lakes Bioenergy Research Center (GLBRC) intensive biofuels research site near Arlington, WI. Field data collected included continuously logged measurements of soil physical properties (soil temperature and soil moisture) at multiple depths to about 1.5m using solar powered data logger systems connected to Time Domain Reflectivity (TDR) equipment and soil thermocouples. During the core of the growing season, weekly measurements of leaf level carbon fixation/assimilation and soil respiration rates were made using a Li-Cor 6400 portable photosynthesis system equipped with an infrared gas analyzer. Leaf level measurements have included using protocol to understand plant assimilation response to a variety of light, temperature, humidity, and internal (leaf) carbon dioxide concentrations within each plant canopy to better parameterize photosynthetic models. Measurements of the diurnal cycle of soil respiration were performed on multiple days during 2011 to better understanding the influence of changing soil temperatures near the surface (10cm) and plant photosynthesis on daily variations in soil carbon dioxide efflux. We also studied the influence of soil respiration measurement location in row crop systems like corn and hybrid poplar on the magnitude of measured values. Measurements of ecosystem leaf area index (LAI) were made weekly during each growing season with a Li-Cor LAI-2000 plant canopy analyzer, and intercepted photosynthetically active radiation was measured using a combination of light bars and quantum sensors designed to detect radiation in the photosynthetically active radiation (PAR) wavelength band. A newly designed rotating shadowband system has been tested and used for the first time as part of this project to provide continuous measurements of both direct and diffuse PAR, so that these can be used in conjunction with numerical models to help calculate net ecosystem exchange (NEE, or the net amount of sequestered carbon) of carbon dioxide between the soil-plant system and the lower atmosphere. Given the overall goal of quantifying carbon sequestration associated with these management systems, the full suite of measurements discussed here will continue as part of Hatch project WIS01586. Dissemination of project information was accomplished through participation in GLBRC events, including annual meetings of the entire GLBRC as well as Area 4 (sustainability science) retreats. Information about this research project has also been communicated at the annual Arlington Agronomy/Soils Field Day, as well as the Wisconsin Crop Management Conference in 2011. Graduate level courses taught by PI Kucharik have discussed research results to help teach students about sustainability issues and bioenergy cropping systems. PARTICIPANTS: The two individuals that have been leading this project are Dr. Chris Kucharik, PI, and Michael Cruse (50% research assistant & PhD candidate in the Environment and Resources program with the Nelson Institute for Environmental Studies at the University of Wisconsin-Madison). Dr. John Norman (Professor Emeritus in the Department of Soil Science at the University of Wisconsin-Madison) has been involved in the design and development of the shadowband instrumentation. Dr. Eric Kruger (UW-Madison Department of Forest and Wildlife Ecology) has provided significant input on how to best capture the response of plant photosynthesis to changing environmental variables using the Li-Cor 6400 portable photosynthesis system. Several undergraduate and graduate researchers have contributed to collecting data; these have included Nicole Caine, Caitlin Moore, Brianna Laube, Alisha David, Chrissy Liu, Tim Burhop, Amelia Perillo, and Nu Lee. TARGET AUDIENCES: Not relevant to this project. PROJECT MODIFICATIONS: In the first year, somewhat surprisingly, we had to make a minor modification to the ecosystem treatments that we would study during the next several years due to the failure of Miscanthus (95 percent winterkill) at the Arlington GLBRC field trials during the winter/spring of 2008-2009. With the failure of Miscanthus in the field, we adjusted to a different ecosystem and began investigating the uniqueness presented by hybrid poplar, which has replaced Miscanthus. Unfortunately, the 50 percent winterkill soil temperature threshold for Miscanthus (the sterile variety that was planted at Arlington) is approximately -3.5C, which was exceeded during the 2008-09 winter and historically has occurred in approximately 50 percent of all winters at Arlington since the mid 1980s. PI Kucharik continues to research the likely impact of cold soil temperatures on Miscanthus survival and ways to use plant residue on the soil surface to reduce the risk of killing temperatures during the winter on 1st year Miscanthus rhizomes. Given that the hybrid poplar trees (planted in 2008) reached a height of 10-20 ft high by the end of 2010, we needed a way to gain access to leaves at the top of the poplar canopies) to measure leaf-gas exchange in the poplar plots. In 2010, a front loader and cage from the Arlington Agricultural Research Station were used to assist in making the measurements, but this was only deemed a short-term fix due to safety concerns. Therefore, a mechanical boom lift was rented in 2011 to make leaf level photosynthesis measurements near the top of the hybrid poplar canopy. Significant modifications over the project duration were necessary for the proper operation of the shadowband system, which is directly responsible for collecting continuous measurements of direct and diffuse PAR data. A larger power supply and stronger anchoring for moving parts within the system were the most important upgrades in 2011, but there are still significant improvements that will be needed before the 2012 season. Most importantly, the arc of the shadow band itself will need to be extended to give proper coverage of the sensor point when the sun is a low solar elevation angles. This will occur over winter 2011-2012 through fabrication done by either Michael Cruse or through the aid of the Physical Sciences Laboratory of the University of Wisconsin-Madison.
Impacts
Preliminary findings have shown phenological differences between crops in relationship to the timing of spring green-up. Also, LAI data in 2010 and 2011 has shown an anomalous early decrease in LAI in August for the hybrid poplar stands that reflects significant leaf drop and early senescence due to fungus. Measurements of peak LAI of corn and hybrid poplar were similar while switchgrass reaches a higher maximum than the other two species. Reductions in LAI occur first in the hybrid poplar and had a negative impact on photosynthesis rates as soon as July; corn was the next crop to see a decline in green leaf area, while switchgrass retained the most green leaf area through the end of the growing season. Measurements of intercepted PAR illustrate that corn and switchgrass had similar interception values late in the season even though LAI is slightly different during that period; hybrid poplar light interception was much smaller than the other two crops later in the season due to the loss of LAI. Soil CO2 flux exhibited seasonal changes and crop differences, peaking in mid-summer. Comparison of soil respiration measurement methods (Li-Cor 6400 portable infrared gas analyzer (IRGA) and a static plastic chamber) in continuous corn stands were found to be significantly different, suggesting that more data needs to be collected in the coming years to better understand reasons for these methodological differences. Comparing soil CO2 flux data within continuous corn plots revealed that there is a significant difference amongst in-row and between-row measurements and that the difference may change over the growing season as roots increase in length and density. Within each crop canopy, shaded (bottom of the canopy position) and sunlit leaves (top of each canopy) generally exhibit differences in maximum attainable photosynthetic rate, how each responds to different levels of PAR and internal (leaf) CO2 concentration. Maximum rates of photosynthesis are similar between switchgrass and corn, with hybrid poplar lower due to its C3 photosynthetic pathway. There were shifts within the growing season in photosynthetic rates that change the efficiency of each canopies' use of PAR; these changes can be seen in the differences between sunlit and shaded leaf fractions as well as between the different crops.
Publications
- No publications reported this period
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Progress 01/01/10 to 12/31/10
Outputs
OUTPUTS: During 2010, field measurements at the intensive research site near Arlington, WI, expanded from the original activities in 2009. Time Domain Reflectivity (TDR; soil moisture sensors) and thermocouple sensors were installed in two additional replicated blocks to give below ground soil moisture and temperature data to a depth of 1.25 meters. These sensors are connected to data loggers (Campbell Scientific, Inc.) that are solar powered to allow for reliable data collection. The CR10X loggers that were already installed in study block 5 in 2009 to measure soil variables had additional sensors added to increase the depth at which data was collected and to increase replication. These instruments have provided a nearly continuous dataset of hourly average data that will feed into numerical models of carbon, water, nutrient and energy cycling. Weekly measurements of leaf level gas exchange and soil CO2 respiration were made using a Li-Cor 6400 portable infrared gas analyzer (Li-Cor, Inc.). Leaf level measurements were made on both shaded and sunlit portions of three crop canopies (continuous corn, switchgrass, and hybrid poplar), which will allow for calculations of canopy photosynthesis. Soil CO2 respiration measurements were made over a transect across study plots to incorporate plot variability and simultaneous measurements of 10cm soil temperature and water content will allow for refinement of ecological models that simulate the effect of changing soil environmental conditions on organic matter decomposition. The ecological models of choice also require measurements of leaf area index (LAI) which have also been taken weekly during the growing season using a Li-Cor LAI-2000 plant canopy analyzer (Li-Cor, Inc.). Hourly measurements of photosynthetically active radiation (PAR; 400-700 nanometers) at the site have been collected using a combination of above and below canopy PAR sensors. The below canopy sensors are LI-191 line quantum sensors (Li-Cor, Inc.) that measure the amount of PAR that reaches the soil surface. A similar light bar is placed above the canopy, allowing hourly measurements of PAR interception by the individual canopies. Two LI-190 point quantum sensors (Li-Cor, Inc.) are also placed above the canopy to measure PAR. Data from these two sensors will be used to correct the errors inherent with the use of the LI-191 light bars and to provide measurement of direct and diffuse PAR through the use of a rotating shadow band. Information about this research project has been communicated at the annual Arlington Agronomy/Soils Field Day in August, as well as the Wisconsin Crop Management Conference in January. Courses at the University of Wisconsin-Madison have also used project data and instrumentation to help teach undergraduate and graduate students both onsite and in the classroom. PARTICIPANTS: The two individuals directly connected to this project are Dr. Chris Kucharik, PI, and Michael Cruse, PhD candidate in the Environment and Resources program with the Nelson Institute for Environmental Studies at the University of Wisconsin-Madison). John Norman (Professor Emeritus of Soil Science, University of Wisconsin-Madison) has been involved in development and construction of the shadow band apparatus for direct and diffuse PAR measurements. Four undergraduate researchers, Brianna Laube (now a M.S. graduate student in the Nelson Institute), Nicole Caine, Caitlin Moore, and Alisha David, have given considerable time to field measurements. Other graduate students and student hourly workers from the UW-Madison Dept. of Agronomy have contributed to environmental measurements and sensor installation. TARGET AUDIENCES: Not relevant to this project. PROJECT MODIFICATIONS: Through discussions with Ryan Kuhl, it was determined that using scaffolding (to gain access to leaves at the top of the poplar canopies) to measure leaf-gas exchange in the poplar plots did not meet safety requirements. It was advised that a mechanical lift and use of a safety harness were necessary for making these measurements. In 2010, a front loader and cage from the Arlington Agricultural Research Station were used to assist in making the measurements. In 2011 and 2012, it is anticipated that an aerial lift will be used. The monthly 24-hour measurements planned for the 2010 field season had to be canceled due to time constraints associated with sensor installation and instrument construction. These measurements should recommence during the 2011 season.
Impacts
Preliminary findings have shown phenological differences between crops in relationship to the timing of spring green-up. Also, this year's LAI data has shown an anomalous early decrease in LAI in August for the hybrid poplar stands that reflects significant leaf drop and early senescence due to fungus. Measured daily maximum leaf assimilation rate for continuous corn and hybrid poplar has exhibited significant differences, and measured assimilation rate versus light intensity (PAR) curves for hybrid poplar and corn illustrated canopy position differences also. Soil CO2 flux exhibited seasonal changes and crop differences, peaking in mid-summer. Comparison of soil respiration measurement methods (Li-Cor 6400 portable infrared gas analyzer (IRGA) and a static plastic chamber) in continuous corn stands were found to be significantly different, suggesting that more data needs to be collected in the coming years to better understand reasons for these differences. Comparing soil CO2 flux data within continuous corn plots revealed that there is a significant difference amongst in-row and between-row measurements and that the difference may change over the growing season as roots increase in length and density.The expansion of data collection in the 2010 season forced us to work through a variety of issues that will lead to improved experimental protocols in the 2011 and 2012 seasons. The increased field time required to collect all necessary data and limitations in equipment availability has forced an adjustment in data collection expectations. While these adjustments should not negatively impact the integrity of the project, more interpolation will be required to fill data gaps than previously expected. Alterations to measurement apparatuses, namely the shadow band system, are ongoing and a full season of measurements using this device is expected in 2011. All other known needs for equipment maintenance have been scheduled to occur before the critical field season begins in the spring of 2011. Through this project's connections, multiple research programs have been able to benefit. The newly installed soil sensors (TDR and thermocouple) will provide data for measurements of water quality (i.e. nitrate leaching), the measurements of LAI have been coupled with other similar measurements leading to comparisons across multiple instruments, and the use of different experimental measurement protocols by different groups at this site will allow for comparison and improvement of methods. Data collected from project instrumentation will also be made available to ecological modelers to improve predictions of the impacts of biomass agriculture on ecosystem services across the Midwest USA.
Publications
- No publications reported this period
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Progress 09/01/09 to 12/31/09
Outputs
OUTPUTS: We do not have traditional outputs to report for the 4 months of support in 2009 (09/01/09-12/31/09), so we instead will briefly report on activities that contribute to the goals and objectives of the project. The bioenergy cropping systems we are studying currently are continuous corn, switchgrass, and poplar, and within these plots at the Arlington Agricultural Research Station (the plots are part of the Great Lakes Bioenergy Research Center [GLBRC] sustainability science experiment) is where the aforementioned preliminary measurements have been collected. We have been collecting soil environmental data (soil temperature and moisture) continuously since June of 2009 (supported by other sources prior to Hatch support as of 9/1/09) and soil CO2 efflux and leaf area index (LAI) data has been collected weekly over the same time period (LAI through the end of the growing season or approximately mid November). Campbell Scientific CR10X data loggers were installed in the study plots in June 2009, and continuously monitor (forming hourly averages) of soil temperature at 2, 10, and 30 cm, as well as soil moisture (volumetric water content) at 15 and 30 cm. Soil CO2 efflux is collected weekly with a Li-Cor 6400 portable infrared gas analyzer, and LAI information is collected with a Li-Cor LAI-2000 plant canopy analyzer. We augmented all of these measurements with 0-6cm soil moisture readings collected with a handheld Theta Probe from Dynamax, Inc. On two dates in August, we collected hourly soil CO2 respiration data over a continuous 30-hour period to better understand how fluxes in and out of these ecosystems are impacted by changes in air temperature and solar radiation. By getting a head start in summer/fall of 2009 on field measurements that will be occurring during the 2010 and 2011 field seasons, we have been able to better understand potential problems we might face in the field while at the same time collect valuable observation data. These additional field measurements have allowed us to plan for the future fieldwork and refine our approaches as well as ecosystems that we will study. PARTICIPANTS: Personnel who have worked on this project are Chris Kucharik, PI, and Michael Cruse (research assistant and PhD candidate in the Environment and Resources program within the Nelson Institute for Environmental Studies at the University of Wisconsin-Madison. Two undergraduate researchers have also participated extensively on field work relevant to this grant (Brianna Laube and Nicole Caine. Other collaborators have been Gregg Sanford (PhD candidate in the Dept. of Agronomy at UW-Madison), and Drs. Randy Jackson and Josh Posner (both with the Dept. of Agronomy at UW-Madison). TARGET AUDIENCES: Not relevant to this project. PROJECT MODIFICATIONS: While not a major change, we have had to make a minor modification to the ecosystem treatments that we will be studying during the next several years due to the failure of Miscanthus (95% winterkill) at the Arlington field trials during the winter/spring of 2008-2009. The experimental protocol does not change, however. With the failure of Miscanthus in the field, we have added a different ecosystem to study (hybrid poplar) and have begun investigating the uniqueness presented by this species. Unfortunately, the 50% winterkill soil temperature threshold for Miscanthus (the sterile variety that was planted at Arlington) is approximately -3.5 degrees celsius, which was exceeded last winter and historically has occurred in approximately 50% of all winters at Arlington since the mid 1980s. Given that the hybrid poplar trees (planted in 2008) are already 10-20 ft high, we will need to install a scaffolding system/tower on those plots in order to perform leaf-gas exchange measurements (i.e. photosynthesis and respiration) on this species at the top of the canopy. If future re-planting of Miscanthus proves successful in 2010, at some point in the future, we made decide to make companion measurements in those plots, but may not be a part of the current funding cycle.
Impacts
We worked through a variety of issues that will allow for fieldwork to progress with fewer unplanned outcomes in the main two field seasons of the project. We were able to investigate the importance of experimental protocol so that the best set of observational data can be collected. For example, we trained multiple undergraduate students on the required equipment that will be used; this increases the potential for flexibility of measurement cycles when individual schedules are in conflict, extends the longevity of expensive equipment, and prevents down time when beginning the new field season. The data collected for the diurnal cycles (and the associated response of the system to temperature and radiation) strengthens the argument for now performing that measurement throughout the following growing seasons on a monthly timescale. In collecting several key pieces of field data, we now have experience acquiring these data, which has allowed us to estimate the amount of time required to accomplish proposed activities and allows for improved planning of future research activities starting in April 2010. We have enhanced communication across several ecological research groups. We have also learned that installing equipment on our project will be of great benefit to multiple research projects. An inventory of the required equipment has been completed and necessary repairs and calibrations are being performed during wintertime before the critical measurement period begins in spring. New equipment that we will need has been ordered before measurement periods begin. The new equipment consists of the necessary components to measuring the soil moisture profile in our research plots to a depth of 1.4 m. This will be accomplished using Time Domain Reflectivity (TDR) technology and new data loggers from Campbell Scientific, Inc. New plans have been created for how best to install the TDR sensors, and orders have been placed for solar panels and rechargeable batteries so that all soil environmental data can be collected with renewable sources of energy, which also decreases the likelihood of lost data due to battery failure.
Publications
- No publications reported this period
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