Wetland Restoration

      Photo97 A restored wetland in Van Buren County, Iowa. Photographer: Lynn Betts. Photo Courtsey of USDA NRCS.
      Category:  Wetland Creation/Restoration
      Practice Type:  Structural
      Landuse/Agriculture Type:  Row Crop, Pasture, Fodder, Rice
      Climatic Zones:  Temperate, Semiarid, Tropical
      Regions:  North America, South America, Africa, Asia
      Pollutants Treated:  Nitrogen, Phosphorus, Sediment
      N Efficiency1:  7-25%
      P Efficiency1:  12-50%
      S Efficiency1:  4-15%

      Description: Wetland restoration activities re-establish wetland hydrology, vegetation and/or functions usually in areas where they existed previously. Wetlands improve water quality by trapping and cycling nutrients and allow for settling of sediments. Wetlands also moderate water flows, reducing downstream erosion. 2

      Implementation Considerations: Wetland restoration can often be very expensive and outcomes can be uncertain. Restored wetlands may not achieve the same level of biodiversity or ecosystem services as undisturbed systems.

      Scalable to small farms? Yes

      Scaling Considerations: Can be combined with agroforestry practices to generate food, fiber or fodder crops.

      1 "Documentation: Source Data, BMP Effectiveness Values." Chesapeake Assessment Scenario Tool. Web. 2013. http://casttool.org/Documentation.aspx .

      2 Estimates of County-level Nitrogen and Phosphorus Data for Use in Modeling Pollutant Reduction Documentation for Scenario Builder Version 2.2." Chesapeake Bay. Dec. 2010. Web. May 2013. http://archive.chesapeakebay.net/pubs/SB_V22_Final_12_31_2010.pdf.


      Windrowing Mature Tree Trunks

      Photo86
      Category:  Nutrient Recycling
      Practice Type:  Management
      Landuse/Agriculture Type:  Palm Oil
      Climatic Zones:  Tropical
      Regions:  South Asia, Africa, South America
      Pollutants Treated:  Nitrogen, Phosphorus, Sediment

      Description: Trunks of mature palm oil trees that have been cut to allow replanting should be recycled in order to return nutrients and organic matter to the soil. Windrowing the trunks gives a slow breakdown of the material. This is the best way to release the nutrients. Conversely, chipping or shredding the trees releases all the nutrients within 2-3 years, and unless the chips are spread over a much larger area than the replanted area, the nutrients released would exceed the uptake capacity of the new trees and result in excessive nutrient losses to the environment. 1

      Implementation Considerations: If trees are diseased or if there is disease in the area alternative disposal may be warranted. If pests are a problem in the area, then it may be best to chip, pulverise or grind the trunks to reduce the time over which the nutrients are available to pests.

      Scalable to small farms? No

      1 "Palm Oil BMP: Reduced Fertilizer Use." World Wildlife Fund for Nature. Web. http://wwf.panda.org/what_we_do/footprint/agriculture/palm_oil/solutions/roundtable_on_sustainable_palm_oil/better_management_practices/fertilizer_use/ .


      Woodchip Bioreactor

      Photo17 Woodchip bioreactor diagram
      Category:  Drainage Control
      Practice Type:  Structural
      Landuse/Agriculture Type:  Row Crop , Animal Confinement
      Climatic Zones:  Temperate
      Regions:  North America, Europe
      Pollutants Treated:  Nitrogen
      N Efficiency:  20-80%

      Description: A woodchip bioreactor is an artificially constructed system that mimics the functions of riparian zones and wetlands. The two main types are beds and walls that are placed in the flow path of water leaving the field. Both have an added carbon source (often woodchips) to support denitrifying microorganisms. The wood chips along with the water flowing through the bed or wall create an anaerobic environment in which bacteria can denitrify the water. The use of woodchip bioreactors has been identified as one means of removing nitrate from subsurface drainage water. Nitrates are removed from the system as the carbon from the wood chips is used by bacteria that break down the nitrate through the process of denitrification. 1

      Implementation Considerations: The key design parameters for woodchip bioreactor construction include 1) assuring adequate hydraulic residence times (minimum of several hours) and 2) using an appropriate carbon source that does not cause clogging. Most research has focused on using wood products as a carbon source in bioreactors.

      Scalable to small farms? Yes

      Scaling Considerations: The technology used for this practice is very simple, but there are no returns to the farmer. They can be incorporated into constructed wetlands as well. Their use will require external factors such as cost sharing.

      1 Miller, T. P. , J. R. Peterson, C. F. Lenhart, and Y. Nomura. 2012. The Agricultural BMP Handbook for Minnesota. Minnesota Department of Agriculture.


      Zero Burning

      Photo87 Oil Palm Replanting. The zero burning technique of replanting is now common commercial practice.
      Category:  Nutrient Recycling, Erosion Control
      Practice Type:  Management
      Landuse/Agriculture Type:  Palm Oil
      Climatic Zones:  Tropical
      Regions:  South Asia, Africa, South America
      Pollutants Treated:  Nitrogen, Phosphorus, Sediment

      Description: In this method, useful parts of oil palm trees are harvested and the remainder are left on the ground where they can be spread out to provide protective ground cover or piled in rows to prevent runoff and erosion instead of burned to prepare the area for replanting or new oil palm plantings. The zero burning method allows nutrients to be released more slowly during decomposition so that they can be utilized by newly planted trees. This reduces per-hectare inorganic fertilizers needed at the time of planting. The organic matter also improves the soil and when used properly, can help with terracing and the reduction of runoff. 1

      Implementation Considerations: The main issue of concern with zero burning is that it might lead to the infestation of beetle pests and stem rot disease. Ploughing, pulverising debris, or planting legumes minimizes this risk.

      Scalable to small farms? No

      1 "Palm Oil BMP: Reduced Fertilizer Use." World Wildlife Fund for Nature. Web. http://wwf.panda.org/what_we_do/footprint/agriculture/palm_oil/solutions/roundtable_on_sustainable_palm_oil/better_management_practices/fertilizer_use/ .