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Publication Date

1995

Keywords

Wetland agriculture; Groundwater--Quality; Agriculture--Environmental aspects

Abstract

In the Prairie Pothole Region (PPR - SO, NO, MN, IA), wetlands classified as "semi-permanent" or "seasonal" can act as groundwater recharge sites. The nutrient filtering capacity of wetlands has been investigated for both natural and constructed wetlands linked to surface water, but there is little information available on their subsequent impact on groundwater quality. This study investigates four seasonal and two semi-permanent wetlands in the PPR of eastern South Dakota. Transitional no-till (TNT) and organic farm (ORG) management systems border the wetlands. The objective is to determine the effects of farm management system on wetland surface water and groundwater quality. This project is part of a more comprehensive study including wildlife-habitat investigation and economic analyses. Water quality data include nitrate (No3--N) and orthophosphate (P043-_p) concentrations from wetland surface water, groundwater at wetland and upland sites, and run-off water from surrounding weirs. The results will be used to determine to what extent PPR wetlands act as sinks for nutrient run-off and establish baseline No3--N and P043-_p data for the development of PPR wetland water quality standards. The results indicate greater surface water N03 --N concentrations in semi-permanent than in seasonal wetlands. Surface water concentrations of Po43--P, however, were greater in seasonal than semi-permanent wetlands. Groundwater sampled near the wetland perimeter had greater P043-_p concentrations than groundwater sampled from nearby upland sites. The farming system effects were observed in weir data that indicated large concentrations of NQ3--N in runoff following nitrogen (N) application in the transitional no-till system. Large No3--N concentrations were also found in groundwater sampled from the organic semi-permanent wetland site which is cropped to alfalfa (Medicago sativa L.) and receives manure application. Orthophosphate concentrations were significantly greater near the seasonal wetland in the ORG (0.68 mg L-1) than the TNT (0.20 mg L-1). Water quality monitoring will continue in 1995, but preliminary results suggest that both wetland classification and adjacent farming practices impact wetland and groundwater quality.

First Page

18

Last Page

24

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