The Assessment of Conservation and Traditional Tillage Systems on Weed Dynamics, Insect Abundance, and Northern Bobwhite Quail Life and Behavioral Patterns

Project Overview

Project Type: Graduate Student
Funds awarded in 2003: $10,000.00
Projected End Date: 12/31/2003
Matching Non-Federal Funds: $6,500.00
Region: Southern
State: South Carolina
Graduate Student:
Major Professor:
William Bowerman
Clemson University


  • Agronomic: corn, oats, soybeans, grass (misc. perennial), hay
  • Additional Plants: native plants


  • Animal Production: feed/forage
  • Crop Production: conservation tillage
  • Education and Training: demonstration, display, extension, mentoring
  • Farm Business Management: whole farm planning
  • Natural Resources/Environment: biodiversity, hedges - grass, habitat enhancement, wildlife
  • Pest Management: field monitoring/scouting, precision herbicide use
  • Production Systems: agroecosystems, holistic management
  • Sustainable Communities: community services


    Our overall research objectives were to assess the differences between innovative soybean tillage systems (no-till) and traditional soybean systems (till) for ecological impacts on pen-raised bobwhites. Chapters of this thesis were divided into three main research areas: (1) population estimate and flush count survey; (2) insect abundance and soybean measurements; and, (3) liberation studies for pen-raised bobwhites.

    Bobwhite densities were relatively low on Clemson University¡¦s Pee Dee Research and Education Center, with the highest mean density estimate of 0.048 bobwhites per hectare found surrounding Field B. Density estimates as great as 6.2 bobwhites per hectare have been reported at Tall Timbers Research Station, Leon County, FL, but a density estimate of 2.5 bobwhites per hectare may be more realistic as a maximum density supported an ideal habitat in South Carolina (Wellendorf 2002). A difference in maximum density (carrying capacity) between South Carolina and northern Florida is primarily believed to be due to variation in native vegetation and soil characteristics.
    Flush counts produced limited data for assessing differences between habitat types because wild bobwhite population densities were low, causing a reduced detection probability which limits sample sizes for statistical analysis. Our data suggest that this method of sampling should not be conducted on areas that have density estimates below 1.00 bobwhites per hectare.

    No-till soybean systems were found to result in faster canopy closure and have a higher insect abundance than both the tilled soybean fields and forested areas for the most beneficial Orders OrthoƒVptera, AraƒWchnida, and ColeoƒWptera/HemiƒVptera. Faster canopy closure with no-till systems was mostly due to the narrow row widths. No-till soybean fields also had more insects per trapping event than field borders for araƒWchnids and coleoƒWpterans and hemiƒVpterans, but not for orthoƒWpterans. Increases in canopy closure and insect abundance from narrow row widths, no-till farming practices, and are respectively are directly related to bobwhite fitness and habitat suitability. Faster and greater canopy closure may have provided added protection from avian predators, which allows bobwhites the capability of utilizing these habitats for nest construction, incubation, and brood rearing activities such as foraging. Insects provide both metabolic energy and protein requirements (both adult hen and chicks) for growth and reproduction during this period characterized as high in stress, due to the predator vulnerability of flightless chicks and energy expenditures of reproductively active hens.

    Liberated pen-raised bobwhites were found to select no-till treatments (soybean and corn combined) more than tilled treatments, field borders, and forested areas for 5 out of 9 fields during release date two and three. Only Field E had higher bobwhite occurrences within tilled than no-till treatments. This may be related to the proximity of a five to six year-old clear cut, the most ideal habitat surrounding only the tilled treatments and an earlier planting period of two weeks for tilled than the no-till soybean field (same split-plot).

    No-till agricultural practices incorporating narrow row widths and transgenic varieties should be more beneficial to bobwhites because these systems could allow for earlier and multiple nesting attempts (Puckett et al. 1995), increased insect abundance (Palmer 1995 and this study) and greater protection for avian predators. These benefits are primarily due to faster canopy closure and greater amounts of soil surface residue left after planting. This form of tillage practice also provides other environmental benefits including: reduced soil erosion, improvements in soil moisture, nutrient-retention of soils, increases in beneficial invertebrates, reduction in fossil fuel usage, less sedimentation of local water bodies, less chemical runoff, reduction in carbon dioxide emission, and as previously stated wildlife enhancement. Our data suggest that no-till systems can possibly aid in the recovery of bobwhite populations, but only if a wildlife habitat management is integrated throughout agricultural fields including: prescribed fire, forested thinning and field border management (to include ditch banks and non-agricultural areas).

    Literature Cited

    Palmer, W.E. 1995. Effects of modern pesticide and farming systems on northern bobwhite quail brood ecology. Dissertation. North Carolina State University, Raleigh, NC. 131 pp.

    Puckett, K.M., W.E. Palmer, P.T. Bromley, J.R. Anderson, T.L. Sharpe. 1995. Proceedings of the Annual Conference of the Southeastern Association of Fish and Wildlife Agencies 49:505-515.

    Wellendorf, S.D., W.E. Palmer, and P.T. Bromley. 2002. Habitat selection of northern bobwhite coveys on two intensive agricultural landscapes in eastern North Carolina. Proceeding of the National Quail Symposium 5:191pp.


    Many farmers in the Southeastern USA have been switching from traditional tillage practices to more recently developed conservation-tillage systems that include narrow row widths and transgenic varieties. Planting herbicide-tolerant varieties in narrow rows should result in fewer weed problems in conservation tillage systems, were cultivation is generally not used for weed control. Implementing these weed-control practices in conservation tillage systems should also result in the use of more environmentally friendly herbicides, in addition to reducing soil erosion and improving soil productivity.

    New production practices must be evaluated not only for their effects on pest populations, but non-targeted species as well. Besides causing shifts in weed and foliar insect populations, new weed-control practices can affect insects living on the soil surface and, hence, the wildlife that feed upon them. Over the last several decades, bobwhite quail (Colinus virginianus) populations have declined in the Southeastern USA, at least partially due to the use of clean tillage practices by farmers. Since quail habitat includes agricultural fields, we conducted a two-year study to examine the affects of new weed-management systems (centering on conservation tillage) on bobwhite quail food availability and habitat quality. An innovative weed-control system for use with conservation tillage was compared to a traditional production system on five split fields at the Pee Dee Research and Education Center in 2002 and 2003. Each field was divided into four sampling areas: conversation tillage system, traditional tillage system, transitional zone, and wooded habitat. Year one (Y1) split fields were all planted with doublecropped soybeans (Glycine max L. Merr) and year two (Y2) fields were planted half in doublecropped soybeans and half in corn (Zea maize L). Quail were monitored using flush counts (Y1) and radio telemetry (Y2) to understand the impacts of tillage treatment and crop selection on quail habitat use and mortality. Insects and vegetative samples were also randomly collected within these four areas to determine habitat attributes including crop canopy coverage for brood and escape cover, insect populations for food availability, and tree stand density for comparison among forested areas. All data such as field location, field characteristics, insect trap location, and forest and intermediate sampling were mapped using GPS and transferred into a GIS system for comparison and modeling.

    Project objectives:

    To determine how new weed-control practices for conservation tillage systems affect quail habitat use or avoidance, foraging, and mortality.

    Identify how an innovative weed control system centered on conservation tillage, narrow row widths, and herbicide tolerant varieties affects insect populations that quail use as a major food source.

    Assess the potential benefits of conservation and traditional tillage systems with respect to pesticide use.

    Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.