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Crop Sciences

University of Illinois at Urbana-Champaign
Benjamin F. Tracy  

Benjamin F. Tracy

Assistant Professor of Agroecology
W-201 Turner Hall
MC 046
1102 S Goodwin Ave
Urbana, IL 61801

Primary Disciplines: Agroecology

Ph:   (217) 265-5313
 bftracy@uiuc.edu

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Research Interests

The general focus of my research program concerns the role of plant diversity in grazed agroecosystems. We have several research projects that address different aspects of this issue.  Summaries of those projects are listed below.

  1. Managing plant diversity in pasture agroecosystems

    Our research group has been working extensively in western Illinois at the University of Illinois Orr Agricultural and Research Center (Figure 1).  Our initial  research showed that establishing species-rich mixtures of forage plants in pastures had little effect on overall productivity or cattle performance (Tracy and Faulkner. 2006. Crop Science. In Press).  Instead of managing pastures for high species richness, we are exploring use of complementary grazing systems to manage plant diversity.  We are using warm-season grasses like Eastern gamagrass (Figure 2) that are most productive in summer months and therefore complementary to cool-season grasses, which are most productive in spring.  As cool-season pastures become less productive in summer (Figure 3), cattle can be moved to more productive warm-season grass pastures (Figure 4)(Figure 5).  Use of warm-season grass pastures in the grazing sequence creates flexibility in the system that may improve overall productivity.  As an added benefit, warm-season grasses also add ecological diversity to the system, even though the species richness of individual pastures is relatively low.
  2. Integration of grassland-based livestock production into sustainable cropping systems

    In 2002, we received funds from the Dudley Smith Initiative (http://www.aces.uiuc.edu/DSI/) to convert a 225 acre corn and soybean farm into a replicated farming systems experiment near Pana, IL (Figure  6).   All 225 acres of the farm were converted to a replicated experiment that integrates cash grain crops with beef cattle.  Each replicate farming system consists of four treatments that include: 1) cropland pasture consisting of equal areas of corn and oats grown for cash crops in summer (Figure 7) and grazed in late fall and winter (Figure 8), 2) continuous corn fields that are managed exactly as corn in cropland pasture plots except without winter grazing, 3) perennial cool-season pastures (Figure 9), and 4) warm-season grass pastures.  In the system, grain crops are grown in the summer while beef cattle graze adjacent perennial pastures.  When the pastures become unproductive in fall, cattle are moved to croplands where they spend late fall and winter grazing a mixture of cover crops and corn residues.

    A multi-disciplinary group of research scientists, extension educators and stakeholders is involved with the project, and we have demonstrated that this farming system can be a viable alternative enterprise for growers in central Illinois.  We are currently in the fifth year (2006) of this 10 year project.  Some preliminary results are listed below.
    • Cattle trampling on croplands in winter causes some soil compaction, but it has not reduced corn yields.
    • Cattle grazing on crop lands suppress weed populations, but presence of cover crops is just as effective.
    • Cattle grazing on winter cropland seems to redistribute nutrients near water sources (due to manure deposition) so it may not influence subsequent crop yields
    • Pastures accumulated more organic matter and had higher quality organic matter then croplands. This happened faster than we expected (within 4 years).
    • Croplands that were grazed in winter accumulated more organic matter had higher quality organic matter than continuous corn plots.  This was likely due to manure and cover crop inputs.
    • The economics of the system are competitive with other livestock systems, but there is room for improvement.  Savings on winter feed for beef cattle are significant.
  3. Biotic and environmental factors that affect the invasibility of pasture communities

    The success of a plant invader is influenced by myriad ecological factors that operate at multiple spatial and temporal scales.  Former post doctoral Research Associate, Ian Renne (ijrenne@ysu.edu) (Figure 10), investigated how resident species diversity, nutrient pulses, water availability and disturbance interact to affect plant invasions in pasture communities (Renne et al. 2006. Ecology. In Press).  Ian also investigated: 1) the allelopathic potential of an invasive forage grass on native prairie plants (Renne et al. 2004. Basic Appl. Ecol. 5:261-269),  2) persistence of disturbance in the aboveground and weed seed bank composition of pasture systems (Renne and Tracy.  2006. Plant Ecology. In Press),  and 3) effects of size, timing and history of disturbance on weed invasions in pastures.  Ian is currently an Assistant Professor in the Department of Biology, Youngstown State University.

Selected Publications

Teaching Responsibilities

CPSC 418 Crop Growth and Management
CPSC 414 Forage Crops and Pasture Ecology
CPSC 437 Principles of Agroecology (Ecology of Cropping Systems)

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