Location: Soil, Water & Air Resources Research2011 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
Air sampling around livestock facilities is complex because of the rapid exchange processes created by the interactions of wind with the buildings. Measurements of the three-dimensional wind structure near and around typical swine and poultry facilities were combined with the lidar particulate scans to characterize the evolution and transport of particulate plumes. Particulate emissions from near poultry and swine buildings do not possess Gaussian characteristics which form the basis of current emission model predictions. Additionally, analysis of high frequency turbulence data from a swine facility provided new insight on deployment of sampling instruments and appropriate sampling intervals for complex surfaces involving buildings and animals. Another study on gas exchanges over a feedlot (25,000 head) and dairy (2,000 head) focused on monitoring the emissions of ammonia, greenhouse gases, and select volatile organic compounds (VOCs). Key findings from the feedlot study were: 1) photo-acoustic infrared analyzers (PA-IR) are challenging to use due to cross interferences of gases and relatively low concentrations of methane, ammonia, and nitrous oxide; and 2) the diversity and concentrations of VOCs increased with temperature and showed vertical gradient with concentrations generally larger at the lower sampling height. Key findings for the dairy study were that major VOCs included alcohols, esters, volatile fatty acids, ketones, and carbonyl compounds and major sources for those compounds were silage piles and feedlot surface. Volatilization of herbicides from soil has been evaluated for 14 seasons; however, until recently, no field investigations monitored both surface runoff and turbulent volatilization fluxes simultaneously. Herbicide volatilization exceeds herbicide runoff losses which contradicts the prevailing thought that surface runoff was thought to be the major off-site transport mechanism for herbicide. For agricultural crops, soil carbon dioxide (CO2) flux measurements were completed approximately monthly between crop harvest and planting and completed biweekly during the growing season. In addition to the survey CO2 flux measurements, continuous long-term chamber measurements were made on the mixed prairie and residue removal studies to develop temperature sensitivity relationships for CO2 evolution. Nitrous oxide (N2O) flux measurements were added to estimate net greenhouse gas flux for each study. Initial laboratory testing of an eddy covariance system for N2O identified issues with temperatures affect the quality of the N2O. Research projects to evaluate the interactions of tillage systems and management inputs were implemented for a corn-soybean production system on water use, nitrogen use, and light capture efficiency. This is a multiple year experiment for monitoring growth and vigor analysis and during the first year an evaluation was made of plant-to-plant variation throughout the growing season. Plant-to-plant variation ranged from 50 to 250% for all growth parameters and remained in this range throughout the growing season. These levels of variation were independent of tillage systems and management inputs.
Hernandez-Santana, V., Asbjornsen, H., Sauer, T.J., Isenhart, T., Schilling, K., Schultz, R. 2011. Enhanced transpiration by riparian buffer trees in response to advection in a humid temperate agricultural landscape. Agricultural and Forest Meteorology. 261:1415-1427.