Skip to main content
ARS Home » Midwest Area » Morris, Minnesota » Soil Management Research » Research » Publications at this Location » Publication #104538
Title: CARBON AND NITROGEN SEQUESTRATION IN NORTHERN NATIVE AND RESTORED PRAIRIE WETLANDS

Author
item Olness, Alan
item EULISS, N - USDI-USGS
item GLEASON, R - USDI-USGS

Submitted to: Wetlands
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/30/2002
Publication Date: N/A
Citation: N/A

Interpretive Summary: Carbon dioxide (CO2) is considered a greenhouse gas. Its production is believed to cause global warming. Soils naturally contain large amounts of both organic and inorganic carbon. Due to cultivation, some soil organic carbon has been lost as CO2. By reversing the process, we can put CO2 back into the soil as organic carbon. A study of northern prairie wetlands shows sthat it is possible to put CO2 back into the soil. Wetlands that had been drained and farmed were restored and the amount of organic carbon was measured. Semi-permanent wetlands (those that have open water in them throughout the year) appear to recover their original carbon content within about 15-20 years. Seasonal wetlands (dry during some part of the summer) show a much slower recovery rate of organic carbon. Pristine wetlands average about 5% carbon in the upper 6 inches of soil. Cultivated wetlands have lost about 1 to 1.5% organic carbon as CO2. This amounts to about 15,000 to 22,500 pounds of carbon per acre. Organic carbon can be stored in the soil as long as the soil remains saturated with water and some nitrogen is added. Soil organic matter is about 10% nitrogen. Thus about 1,500 to 2,250 pounds of nitrogen must be supplied either from fertilizer or nitrogen fixation to restore the organic carbon in these soils. With drainage of semi-permanent wetlands, much inorganic carbon was flushed from the soil. Restoration of the wetlands did not recover inorganic carbon quickly. This shows that wetlands that have too much inorganic carbon can be restored by drainage. The results will aid wetland managers in the restoration of wetlands to productive waterfowl habitat and in removal of CO2 from the air. The results have identified management practices land restoration.

Technical Abstract: Evaluation of wetland projects in the Prairie Pothole Region of the northern Great Plains is needed to determine the degree to which they achieve restoration. A total of 208 wetland sites each including pristine, drained and non-drained cultivated sites and sites that had been restored were sampled. Soil samples were collected from class III (seasonal) and class IV (semi-permanent) wetlands to a depth of 60 cm for analysis of their soil organic carbon (OC), inorganic C, and total nitrogen (N). Soil cores were composited from deep marsh, shallow marsh, and wet meadow areas, segmented at 0 to 15 cm, 15 to 30 cm, and 30 to 60 cm and dried. Pristine sites contained 4.1 to 5 % OC and contained 1 to 1.5% more OC and 0.08 to 0.12% more N in the 0- to 15-cm depth zones of both class III and IV wetlands than their drained and non-drained but cultivated counterparts. The C and N concentrations decreased with depth and no effect of cultivation was observed at depths greater than 30-cm except for carbonate-C in the semi-permanent wetlands and appear to equal those of pristine sites within 20 years. No measurable gains in C and N concentration in restored seasonal wetlands were noted. Both C and N concentrations increased with age of restoration. Soil carbonate levels in seasonal wetlands appear unaffected by drainage or tillage relative to those of pristine sites. Drainage and cultivation resulted in a loss of about 36,000 kg of carbonate ha**-1 from the surface 60-cm of semi- permanent wetlands. Carbonate levels recover much more slowly than C or N in semi-permanent. Organic C:N ratios were almost constant at about 10.0 to 10.8 within the wetland soils and decreased very slightly with depth.