Location: Soil, Water & Air Resources Research2013 Annual Report
1a. Objectives (from AD-416):
Project objectives are: 1) Measure and model the impact of agricultural systems (animal and cropping) on air quality components to identify and develop potential mitigation strategies, 2) Measure and model the impact of agricultural systems on greenhouse gas emissions and develop and evaluate potential mitigation strategies, and 3) Measure and model soil and atmospheric factors limiting water, nitrogen, and light use efficiency of annual and perennial cropping systems to determine how they can become more resilient to climate change.
1b. Approach (from AD-416):
Studies across the soil-plant-atmosphere continuum in this project will develop new methods for quantifying emission and dispersion (particulates, NH3, VOC’s) from animal and cropping systems, improve methods for measuring different compounds in the air to provide increased quantitative capability to measure impacts of CAFO’s on air quality, determine greenhouse gas emissions (N2O, CH4, CO2) from cropping systems, and quantify effects of changing climate on water, light, and nitrogen use by crops. The initial development of a lidar-based approach to measure plume dynamics from animal facilities will be evaluated to produce a remote-sensing approach that will be used to guide sampling methods that use point-based samplers. These data will be collected over a range of facilities and throughout the day to capture the range of atmospheric stability conditions. Air sampling methods for volatile organic compounds will be accomplished with a range of methods from sorbent tubes and canisters. These will also be coupled with methods to measure the volatile organic compounds attached to particulates. These observations will be collected in different livestock facilities. Greenhouse gas emissions will be quantified using soil chambers for a range of soil management and nitrogen management studies to quantify the emissions throughout a year. Measures of water, nitrogen, carbon accumulation, and light use efficiency will use an integrated approach that blends micrometeorological with physiological measurements. These experiments will be conducted using field-scale environments and will integrate all efficiency factors into a combined assessment. The energy balance approach used in these studies blends the fast response of CO2 and H2O vapor signals with sonic anemometers, net radiation components, soil heat flux, and surface temperature along with remote sensing to obtain growth characteristics of the crop. Studies will be conducted in the rhizotron to assess the impact of rapidly induced temperature changes on crop physiological responses under a range of soil water conditions. Accomplishing these three objectives will result in the development of agricultural practices and mitigation strategies that reduce environmental impact, while maintaining or increasing productivity. Mitigation strategies to reduce GHG emissions will balance agricultural production efficiency and increased carbon capture and nitrogen use efficiency. Climate change and its impact on cropping systems raise additional concerns regarding resilience of current production practices and plant adaption to those changes. Methods are needed to quantify plant-climate interaction to link field observations with simulation models for corn, soybean, wheat, and native prairie systems. Developing a long-term program to quantify plant response to climate anomalies will also establish a database for developing more resilient crop production systems. This research will enhance scientific knowledge and provide information for producers and policymakers to maintain the viability of agricultural systems.
3. Progress Report:
Objective 1. Quantifying accurate particulate and gas emissions to the atmosphere is essential to addressing air quality issues from livestock production facilities. Particulate emissions from animal production buildings do not possess Gaussian characteristics which form the basis of current emission model predictions. New retrieval algorithms for lidar scanned data were developed and are being tested against previous year’s data. Advanced analysis of high frequency turbulence data are being employed to develop turbulence intensity ratings. A study in Delaware combined lidar, turbulence, and active particulate samplers to evaluate the effectiveness of a dense shelterbelt in reducing particulate emissions. A new protocol was developed for analysis of particulate matter (PM). In another study, a new parameterization method that included optimum temperature of extraction, extraction time, and sample size was developed to improve quantification of PM from livestock feedlots. Objective 2. Long-term monitoring of two common pre-emergent herbicides continued for the 15th year. In 2013 weak stability conditions not previously encountered influenced metolachlor and atrazine volatilization. A nitrous oxide (N2O) study during the third year compared the effects of soil N2O emissions from soil cropped to corn treated with enhanced efficiency fertilizers (EEFs) and conventional fertilizers. An eddy covariance N2O flux system was deployed in a corn field in Beltsville, MD. Preliminary N2O flux data were are being analyzed. In addition to the trace gas emissions survey, carbon dioxide (CO2) flux measurements were augmented to include two continuous soil CO2 flux measurement systems in the residue removal study to continue development of temperature sensitivity relationship for CO2 evolution. There is a need to evaluate and refine thermal-based two-source remote sensing models and tools for quantifying water use (evapotranspiration, ET) and root zone water availability and to improve water management strategies for vineyards. A multi-year study was initiated in April 2013 to conduct continuous intensive field experiments over vineyards to measure ET, root zone soil moisture, and biophysical data in concert with high resolution aircraft remote sensing imagery. Objective 3. Interactions of temperature, soil water availability, and nutrients were evaluated for corn and soybean using flux data across different growing season conditions. The effect of increasing minimum temperatures increases the nighttime respiration decreasing the photosynthetic rate the next day and is exaggerated by soil water deficits. Extreme temperatures at different phenological stages impact the rate of senescence and corn grain yield. A study is underway to evaluate the response of corn hybrids from different eras to temperature extremes in a controlled environment. Analysis of yield gaps in soybean from Iowa, Kentucky, and Nebraska showed that soil is a major determinate in the effect of variable weather on grain yield.
1. Emission and transport of dust and gases from livestock production facilities. Mitigation and reduction of particulates from production facilities are needed to lessen environmental impacts. While Buffers and shelterbelts have been planted around many facilities, it is not known how effective they are at reducing particulate and gas emissions downwind. Researchers from University of Delaware (UD), University of Iowa, Oklahoma State University, Pennsylvania State University, University of Maryland, and several USDA-ARS locations have joined efforts to address the effectiveness question. At a UD poultry research site with a designed vegetative environmental buffer, researchers released known quantities of particulates. Towers equipped with instrumentation to measure turbulence in the air, particulate concentrations, and other atmospheric characteristics have been deployed downwind from the buffers. Light detection and ranging (LiDAR) measurements mapped the spatial extent of particulate transport in the vertical and horizontal directions. This year’s results demonstrated that vegetative barriers are much more porous than previously believed thus underestimating the efficacy of barriers to reduce particulate emissions. Previous analytical methods for determining specific volatile organic compounds from particulates have relied on laborious solvent extraction techniques requiring large amounts of sample and limiting characterization to mainly total suspended particles. An improved method was developed that dramatically reduced sample sizes to approximately 1-2 orders of magnitude lower than previous methods and reduced sample preparation time from hours to minutes. This enables the potential for high throughput analysis/screening of particulate matter (PM) and the capacity to analyze multiple PM-size fractions. This accomplishment significantly improves the measurement resolution of organic compounds emitted from animal facilities which improves emission estimates.
2. Herbicide volatilization and runoff. Although numerous studies have been conducted on herbicide volatilization and herbicide runoff, there is a lack of understanding of how these two processes relate to one another during a field season. To increase our understanding of the impact of local meteorology, soils, and pesticide chemistry on herbicide off-site transport, a long-term (>15 year) field-scale experiment in Beltsville, MD, was conducted by ARS scientists where pre-emergent herbicide (atrazine and metolachlor) volatilization and surface runoff losses were simultaneously measured and evaluated. This length of study is necessary to understand the differences among years and to provide a greater insight into the relationships between runoff and volatilization. Results from this long-term study showed volatilization losses often times were up to 25 times greater than surface runoff losses and that volatilization losses into the air have to be considered when developing environmentally sustainable practices. Data results from this unique long-term research will influence United States Department of Agriculture (USDA) and United States Environmental Protection Agency (USEPA) policy with regard to herbicide transport and to developing or improving pesticide behavior models.
3. Quantify the effectiveness of agricultural fertilizer management practices to reduce ammonia (NH3) and nitrous oxide (N2O) emissions into the atmosphere that can contribute to climate change. Data acquisition continued for the third year of a multi-year study to evaluate growing season N2O emissions. In the third year of the study, conventional fertilizers and an additional enhanced efficiency fertilizer formulation (EEF)were evaluated. Reductions in cumulative seasonal N2O emissions from EEF treatments were not observed in any of the study years. Additionally, N2O emissions were significantly greater than emissions from no fertilizer treatment. Results indicate that, due to the variable nature of N2O emissions induced by rainfall events, reduction of N2O emission through the use of EEFs may be limited in rain-fed regions. Understanding the role of soil carbon cycling and carbon storage is limited but is needed to develop strategies involving land use to help offset carbon dioxide emissions. Land use change not only has the potential to affect carbon (C) cycling and soil C storage but also the soil water and thermal regimes with implications for various ecosystem services. Measurement of soil carbon dioxide (CO2) fluxes, changes in soil C storage, and selected ecosystem services were completed on field studies for year three in the Great Plains, U.S.A., and the Central Russian Upland, Russia. Measurement protocols have been expanded in year three to include carbon isotope measurements throughout the one meter profile depths as part of an ongoing collaboration with Russian scientists to expand the knowledge base of carbon storage in soils across international lines. Results found this year suggest that carbon cycling and storage processes are remarkably similar across variable soils and climates suggesting the potential for universal carbon mitigation strategies involving land management practices.
4. Climate impacts on agricultural crops. Understanding the effect of climate on agricultural production is a necessary foundation from which to begin to evaluate potential adaptation strategies. ARS scientists in Ames, IA, evaluated the impacts of changing climate on annual grain crops, specialty crops, and perennial crops. Long-term records of grain yields across the United States demonstrated that within season weather impacts during the period from the late 1950s to the early 1970s were relatively minimal, during the period from the early 1970s through the early 1990s there was large variation among years caused by more volatility in weather conditions, and followed by the period from the early 1990s through 2009 in which the weather impacts diminished. There has been an increase in annual variation in crop yields across the United States since 2009 due to an increase in temperature and water stress during the growing season with the largest impact during the 2012 drought. An analysis of Iowa, Kentucky, and Nebraska soybean production from 1950 through 2011 revealed that mean county yields and the deviations from the attainable potential yield were related to the national crop commodity productivity index. Applying irrigation water eliminated this relationship because soil water holding was no longer a limiting factor affecting grain yield. To maintain efficient crop production producers will benefit from soil management practices which enhance soil water availability and reduce soil water evaporation, through increased crop residue cover and soil organic matter content, coupled with nitrogen management will reduce impact of the drought (20% yield reduction) compared to conventional farming systems (40-50% yield reduction). Increased weather variability will require the integration of soil management and crop management into effective adaptation strategies.
Hatfield, J.L. 2012. North American perspectives on potential climate change and agricultural responses. In: Hillel, D., Rosenzweig, C., editors. Handbook of Climate Change and Agroecosystems. Hackensack, NJ: Imperial College Press, World Scientific Publishing. p. 33-55.