||Water quality is a major concern in the Southeast (SE) Coastal Plain because of extensive links among sensitive streams, wetlands, and water bodies. The challenge in this region is particularly difficult because the soils are sandy and the shallow groundwater is linked with streams. Problems are exacerbated by the recent expansion of animal production and of high input crops such as cotton and vegetables. Farmers must address nonpoint source pollution using better chemical management, improved animal waste management, and riparian/wetland landscape features.
The North Carolina project is part of a national program entitled, "Agricultural Systems for Environmental Quality (ASEQ). It builds upon a 5-year USDA Water Quality Demonstration Project on the Herrings Marsh Run watershed near Kenansille in Duplin Co., North Carolina. The project area is typical of crop and livestock production with rapid growth occurring in the swine, poultry, cotton, and truck crop industries. The project involves Federal, State, and local agencies, farmers, private industries, commodity groups, and the general public.
Site-specific crop management as a best management practice.
- Yield mapping: Commercial equipment makes possible the customized applications of seed, fertilizer, and pesticide to specific parts of a field. This is particularly important in the SE Coastal Plain with its highly variable soils. Adoption of site-specific farming (SSF) technology is being encouraged by use of demonstration projects with farmer cooperators and commercial yield monitors. Delineating areas of high and low crop yield should increase adoption of SSF for optimizing field inputs, ultimately saving money and improving water quality.
Enhance efficiency of constructed wetlands to remove N and P from swine wastewater.
- Constructed wetlands: Disposal of wastewater generated by confined swine production can cause odor and water pollution problems. When farmland is limited, constructed wetlands can allow for safe disposal of lagoon effluents. Nitrogen removal efficiencies up to 70 percent were obtained using constructed wetlands planted to rush/bulrush or cattail/bur-reed plant mixtures with nitrogen application rates up to 15 pounds per acre daily. In a microcosm study, wetland plants grew vigorously with ammonia-N concentrations up to 240 ppm. However, conversion of ammonia to nitrate (nitrification) appears to be the limiting factor for N removal.
- Nitrification: Three technologies are being evaluated for their potential to enhance nitrification of lagoon wastewater. An overland flow treatment removed 59 percent of N applied at a 50 pounds per acre per day rate. A media filter treatment transformed up to 32 percent of the inflow total N into nitrate when wastewater was recycled four times. Immobilization of nitrifying microorganisms in polymer pellets resulted in faster nitrification rates and smaller reactors. The rate of nitrification with polyvinyl alcohol pellets is about 360 ppm of ammonia-nitrogen per day.
- Solid removal: Solids separation has the potential to reduce N treatment required. Polyacrylamide (PAM) is very effective for separating nutrients before the waste enters typical lagoon treatment. Low rates (25-100 ppm) can remove 80 percent of suspended solids, organic N, and organic P from flushing effluents. PAM treatment provides new alternatives for waste disposal. The solids can be composted, processed for refeeding, or transported to nutrient deficient cropland.
- Decision support system: WATERSHEDSS is a decision support system that was developed through an EPA grant. Its purpose is to help managers determine appropriate systems and their placement on the landscape for particular water quality problems. Data collected on the effectiveness of the riparian and wetland systems will be included in a BMP database that is part of WATERSHEDSS.
- Workshops: Educational workshops led by NCSU extension personnel are presenting state-of-the-art information and facilitating technology transfer. The first was a Site-specific Farming Field Day in June 1996 at Goldsboro, NC. Future workshops include 1) Landscape features, 2) Constructed wetlands, and 3) Site-specific farming.
ARS - Patrick Hunt, 803-669-5203
NCSU - Frank Humenik, 919-515-6767
NRCS - George Stem, 919-873-2103