Economic and Environmental Contributions of Wetlands in Agricultural Landscapes

The purpose of this project was to determine key environmental and economic relationships between agricultural practices and wetlands in the Prairie Pothole Region (PPR) of eastern South Dakota. Water quality and water quantity variables were the key environmental parameters examined. Economic cost and returns by farm management system and wetland proximity were the key economic parameters. The three farm management systems examined were conventional {CON), transitional no-till (TNT), and organic (ORG) • 'lhe 'lNr an::i a:N management systems used synthetic fertilizers and chemical pesticides. The ORG system used no synthetic fertilizers and generally no chemical pesticides. The ORG system had greater emphasis on alfalfa and lower emphasis on corn and soybean production. Water budgets were determined for upland and wetland sites. At the wetland site, runon was the major input to the water budget (60%). overflow accounted for 36% of the wetland output and surface storage /seepage accounted for 40%. Evapotranspiration at the wetland site was much lower than at the upland site. Nitrate concentrations were consistently higher in the semipermanent wetland areas than the seasonal wetland areas. The data show a steady decrease in phosphate concentration as we move upland in the landscape. Higher concentrations in wetland than upland groundwater may indicate that some soluble P is moving through the system and/or the sorption capacity of wetland soils is exceeded. . Economic returns and costs of the three farming systems were estimated for 1992 - 1994 at the whole-farm and crop field level. The relative ranking of net returns by management systems were: TNT > CON > ORG, unless organic premiums are a major source of gross income. Production costs per acre by management system from lowest to highest were ORG < TNT < CON. The organic (ORG) system had lower reported average yields and considerably lower production costs per acre than the other management systems. The TNT system had the least diversity of crop rotations, intermediate-level production costs, and similar yields or higher yields than reported in the CON system. The added costs of more tillage and machinery operations in the CON system exceeded any reduction in chemical costs compared to the TNT system. Biomass production and most corn/soybean yields were lowest adjacent to wetland sites and increase to peak production at 150' to 300' feet out. Several years of crop budget estimates for ORG, CON, and TNT fields adjacent to monitored wetland sites indicated substandard net returns in most years.