Wetland Soils Research and Applications: Past, Present, and Future.

Wetland soils research has been conducted for over 100 years in several disciplines: soil chemistry, soil fertility, and pedology.  Up until the 1980’s, the work in both disciplines was focused on agricultural applications.  Pedology developed techniques to map the poorly drained soils so they could be drained for agricultural production.  Soil chemistry focused on how the drained soils needed to be managed to grow agricultural crops.  Drained wetland soils were made suitable for production of most crops including corn, soybeans, cotton, etc. by regular applications of fertilizer and lime.  Not all poorly drained soils were drained for agricultural purposes.  Rice production needed ponded conditions, and soils were compacted and diked to pond water above the soil surface.  Also in the 1980’s, wetland laws were enacted at both the federal and state levels to prevent the drainage or filling of wetlands.   Under the federal policy of “no net loss” of wetlands, permits were required to drain or fill a wetland.  As part of the permit, the land developer would be required in most cases to restore or create a wetland to replace the acreage lost by draining or filling.  To implement these laws, pedologists developed hydric soil field indicators to identify the soils in wetlands that needed to be protected.  At this time, these indicators are being used by the USDA, US Army Corps of Engineers, and USEPA to enforce wetland protection laws.  Restoration of wetlands is frequently done on agricultural land that was drained that received annual applications of fertilizer and lime.  These areas are restored by plugging drainage ditches and planting wetland vegetation.  Residual nutrients remaining in the soils of restored wetlands are available for the wetland vegetation.  However, some nutrients such as P, are being mobilized following wetland restoration and may drain from the site before being taken up by plants, and may contribute to eutrophication downstream.  Future research in wetland soils will have to develop ways to manage excess nutrients coming from lands used for agriculture.