Potential for nitrate-nitrogen leaching in a silvopastoral system compared with open pasture and loblolly pine plantation

Project Overview

Project Type: Graduate Student
Funds awarded in 2004: $9,998.00
Projected End Date: 12/31/2006
Grant Recipient: University of Florida
Region: Southern
State: Florida
Graduate Student:
Major Professor:

Annual Reports


  • Agronomic: general hay and forage crops, grass (misc. perennial), hay
  • Additional Plants: trees


  • Animal Production: feed/forage
  • Crop Production: agroforestry, forestry, intercropping, nutrient cycling, tissue analysis
  • Production Systems: holistic management, integrated crop and livestock systems


    Soil solution nitrate-N concentrations at 0.3 m below soil surface were less in silvopastures than open pasture or conventionally thinned pine plantation at various time periods during this study. Fertilization with N resulted in time-delayed spikes in soil solution nitrate-N concentrations. At 1.2 m below soil surface, soil solution nitrate-N concentrations were less in the silvopastures and the open pasture than in the thinned pine plantation only during winter months. The results partially corroborate our hypothesis of reduced nitrate-N leaching in silvopastures compared with the other investigated production systems. Fertilization rates designed for forage production generally improved tree nutritional status.


    Silvopasture is an intentional integration of trees, improved forages and livestock into one management system (Sharrow 1999, Sharrow and Ismail 2004). Formerly known as tree-pasture or pine-pasture, silvopasture is one of several agroforestry practices steadily gaining popularity in the southeastern U.S. (Bendfeldt et al. 2001, Grado et al. 2001, Husak and Grado 2002, Workman et al. 2003). Well-managed silvopasture can improve cash flow of small family farm operations (e.g. Dangerfield and Harwell 1990) and provide many environmental benefits (Nowak and Blount 2002). Silvopastures are usually established by planting trees in existing pastures with enough open space left between the rows of trees to allow for forage production (Grado et al. 2001, Husak and Grado 2002). However, these tree-forage-livestock systems can also be established after commercial thinnings of pine plantations (Clason 1995, Clason 1999). Abundance of mid-rotation age pine plantations in the South creates ample opportunity for such conversions to take place.

    Many non-industrial private forest landowners may adopt alternative forest-based enterprises if they are convinced of their profitability and environmental qualities (Alavalapati et al. 2004). To test the feasibility and environmental benefits of mid-rotation pine plantation conversion to silvopasture in North Florida, an 18-year-old loblolly pine (Pinus taeda L.) stand was thinned to two silvopastoral tree configurations while the control was conventionally 5th row thinned. Warm- and cool-season forages were established in both the silvopastoral systems and on a nearby open pasture. These tree and pasture systems are subject of a doctoral research project of Susan Bambo, who is a graduate student at the University of Florida in the School of Forest Resources and Conservation. One of the hypotheses tested in this project was that silvopastoral systems reduce soil nitrate-N leaching compared with open pastures and pine plantations. Recently, Allen et al. (2004) found reduced soil nitrate nitrogen leaching in a pecan (Carya illinoensis K. Koch) – cotton (Gossypium hirsutum L.) alley cropping system, but to our knowledge, similar environmental benefits of silvopasture have not yet been documented. In addition, we tested a hypothesis that fertilization for forage production improves tree nutritional status in silvopastoral systems.

    Project objectives:

    • Determine differences in soil nitrate-N leaching among silvopasture, conventionally thinned loblolly pine plantation and open pasture.

      Determine effects of silvopasture fertilization for forage production on tree nutrition.

    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.