Three Options for Cleaning Barn Exhaust Air

Reducing aerial emissions and improving air quality is a common goal in the livestock and poultry industries. This webinar presents three approaches to reducing aerial emissions from barn exhaust air, using combinations of wet scrubbing, electrostatic precipitation, filtration and enhanced dispersion. This presentation was originally broadcast on March 29, 2019. More… Continue reading “Three Options for Cleaning Barn Exhaust Air”

Vegetative Environmental Buffers (VEBs) for Mitigating Air Emissions from Livestock Facilities: A Review

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Air emissions from livestock facilities are receiving increasing attention because of concerns related to nuisance, health and upcoming air quality regulations. Vegetative buffers have been proposed as a potential cost effective mitigation strategy to reduce dust, odor and other air pollutants from farm and can be an important part of air quality management plan. However, the effectiveness of vegetative buffers in mitigating air emissions seems to be site specific and can be affected by many factors. This study aims to provide a thorough literature review on the performance of vegetative buffers in mitigating air emissions, to investigate critical factors, and to identify research gaps. The results will be used as basis for planning future wind tunnel and field studies. The ultimate objective is to develop general guidance for vegetative buffer design and to demonstrate the variety and effectiveness of vegetative buffers for mitigating air emissions from livestock facilities.

Why Study Trees As a Potential Odor Management Strategy?

Vegetative environmental buffers (VEBs) have been proposed as a mitigation strategy for air emissions from livestock facilities. Survey indicated producers are interested in using VEBs for odor management. But lack of information on performance, cost and technical guidelines are barriers to adoption of VEBs.

What Did We Do?

Review published research on effectiveness of VEBs for mitigating air emissions from livestock facilities.

What Have We Learned?

VEBs have been examined primarily in swine and poultry farms. Iowa, Pennsylvania and Delaware are actively involved in research and implementation of VEBs for livestock farms. VEBs are potential cost effective strategy for reducing dust (by up to 56%), odor (by up to 68%), NH3 (by up to 54%) and H2S (by up to 85%) from farms, although effectiveness and costs are highly variable and depend on site specific design. Most effective reduction occurs just beyond the VEBs. Wind tunnel simulation on barriers at roadside showed that percentage reduction of pollutants decreasing with downwind distance, and they are generally below 50% beyond 15 barrier height.

Mitigation Mechanisms of VEBs

Future Plans

Measure the concentrations of multiple air emission constituents at various distance from a swine facility with and without the presence of a VEB under various weather conditions; determine the effectiveness of the VEB under various design parameters (height and depth) and evaluate how height and depth of the VEB will affect the mitigation effectiveness; develop design suggestions and best management procedures to utilize a VEB in order to maximize effectiveness with limited costs. 


Zifei Liu, Assistant Professor, Kansas State University.

Ronaldo Maghirang, Pat Murphy, Kansas State University

Additional Information


The authors are solely responsible for the content of these proceedings. The technical information does not necessarily reflect the official position of the sponsoring agencies or institutions represented by planning committee members, and inclusion and distribution herein does not constitute an endorsement of views expressed by the same. Printed materials included herein are not refereed publications. Citations should appear as follows. EXAMPLE: Authors. 2013. Title of presentation. Waste to Worth: Spreading Science and Solutions. Denver, CO. April 1-5, 2013. URL of this page. Accessed on: today’s date.

Odor Mitigation Using Vegetative Environmental Buffers Research Summary

Why Study Trees for Controlling Odors from Livestock and Poultry Buildings?

The objective of this research is to evaluate the bio-physical, economic and social efficacy of the use of Vegetative Environmental Buffers (VEBs) – purposefully planted linear arrangements of trees and shrubs – to incrementally mitigate livestock and poultry odor. Our research has demonstrated that tree barriers can help impede, alter, absorb, and/or dissipate livestock odor plumes and other emissions prior to contact with people. As air moves across vegetative surfaces, leaves and other aerial plant surfaces remove some of the dust, gas, and microbial constituents of airstreams. Trees and other woody vegetation also enhance localized air dispersion by increasing mechanical turbulence. Our research program into the efficacy of VEBs involves a multi-disciplinary, multi-species and multi-analytic perspective. Related: Archived webcast on “Trees, Shelterbelts, and Windbreaks for Mitigating Livestock and Poultry Odors


The efficacy of VEBs in mitigating livestock and poultry odor is being examined from a three- pronged perspective measuring efficacy in:

  1. field measured bio-physical terms (e.g. physical reductions in downwind movement of particulates, odor and ammonia and long-term tree health)
  2. financial feasibility terms at the farm-level (e.g. total costs of VEB establishment and maintenance vs. producer willingness to pay), and
  3. in terms of social approval of the use of VEBs (e.g. evaluation of the impact of VEBs on production site aesthetics and consumer willingness to pay for environmentally friendly meat products).

The quantification of physical odor mitigation via the use of VEBs is approached with field trials using full size VEB systems (multiple rows of trees) at working poultry and swine facilities as well as using scale models of these facilities for wind tunnel examinations and advanced computer simulation.

Custom rate financial data has been collected and applied to a range of livestock facilities (e.g. differing VEB designs, production scale, etc.) to calculate typical upfront and long-term costs. Producer willingness to pay has been determined via multi-state producer surveys. Social opinion data was collected via multi-state consumer focus groups (utilizing photo elicitation techniques) and a series of integrated social surveys.

Can Trees Reduce Odor Movement?

Baseline physical data suggests that VEBs can contribute up to a 10% reduction in the movement of odor downwind. The technology broadly applied at the farm level seems to be financially feasible to most swine producers – with total costs ranging from $0.01 to $0.33 per pig produced; these costs by and large being well below maximum producer willingness to pay for the use of VEBs. And social surveys in IA and NC show strong social support and appreciation of the use of trees for air quality purposes with strong social agreement that VEBs improve the aesthetics of confinement production.

Why is This Important?

Affordable, tertiary odor mitigation technology with the added benefit of being socially acceptable is a strong compliment to any comprehensive manure management program at production sites .

For More Information

Author: John Tyndall, Iowa State University

Visit the Iowa State University vegetative environmental buffers website.

Read the following article: Tyndall, J.C. and J.P. Colletti. 2007. Mitigating Swine Odor with Strategically Designed Shelterbelt Systems: A Review. Agroforestry Systems. Volume 69, Number 1/January, 2007.

This report was prepared for the 2008 annual meeting of the regional research committee, S-1032 “Animal Manure and Waste Utilization, Treatment and Nuisance Avoidance for a Sustainable Agriculture”. This report is not peer-reviewed and the author has sole responsibility for the content.