Comparison of Surface Water Quality and Yields from Organically and Conventionally Produced Sweet Corn Plots with Conservation and Conventional Tillage.

Organic agricultural systems are often assumed to be more sustainable than conventional farming, yet there has been little work comparing surface water quality from organic and conventional production, especially under the same cropping sequence. Our objective was to compare nutrient and sediment losses, as well as sweet corn ( L. var. ) yield, from organic and conventional production with conventional and conservation tillage. The experiment was located in the Appalachian Mountains of North Carolina. Four treatments, replicated four times, had been in place for over 18 yr and consisted of conventional tillage (chisel plow and disk) with conventional production (CT/Conven), conservation no-till with conventional production (NT/Conven), conventional tillage with organic production (CT/Org), and conservation no-till with organic production (NT/Org). Water quality (surface flow volume; nitrogen, phosphorus, and sediment concentrations) and sweet corn yield data were collected in 2011 and 2012. Sediment and sediment-attached nutrient losses were influenced by tillage and cropping system in 2011, due to higher rainfall, and tillage in 2012. Soluble nutrients were affected by the nutrient source and rate, which are a function of the cropping system. Sweet corn marketable yields were greater in conventional systems due to high weed competition and reduced total nitrogen availability in organic treatments. When comparing treatment efficiency (yield kg ha /nutrient loss kg ha ), the NT/Conven treatment had the greatest sweet corn yield per unit of nutrient and sediment loss. Other treatment ratios were similar to each other; thus, it appears the most sustainably productive treatment was NT/Conven.

Effect of development on water quality for seven streams in North Carolina.

In this study, baseflow and storm discharges were monitored in seven watersheds of varying development density to document the effects of development on stream water quality. In addition, two of the watersheds contained package wastewater treatment facilities, which were evaluated as an alternative to residential on-site septic systems. Monthly grab samples of baseflow and flow-proportional samples of storm event discharge were collected and analyzed for nitrogen, phosphorus, sediment, and bacteria. For the five watersheds without wastewater treatment facilities, a significant linear relationship was documented between fecal coliform and enterococci levels in baseflow samples and the percentage of residential or impervious area. For the two watersheds with wastewater discharge, bacteria levels were significantly greater than those from the two relatively undeveloped watersheds. These results indicate that bacteria levels increased with increasing residential development even if many of the septic systems were replaced by a community wastewater treatment system. Computed annual export rates for ammonia nitrogen (NH3-N) were correlated to the percentage of impervious surfaces in the watersheds, while the rates for other nitrogen forms, total phosphorus, and total suspended sediment were not. Annual export rates from the two mostly undeveloped watersheds were greater than a compilation of rates for undeveloped areas across the USA. Export from the four watersheds with more than 68 % residential land use was less than those reported from local and national studies of residential areas.

Effects of development on runoff and pollutant export.

Runoff from two similar drainage areas in the Piedmont physiographic region of North Carolina was monitored simultaneously for 5.6 years. One of the drainage areas was developed as part of a large residential subdivision, while the other remained in woods and agricultural fields. Runoff volume was 68% greater for the developed compared with the undeveloped area, and baseflow as a percentage of overall discharge was approximately 0% compared with 25% for the undeveloped area. Overall annual export of sediment was 95% greater for the developed area, while export of nitrogen and phosphorus forms was 66 to 88% greater for the developed area. These results document the significant increases in runoff, sediment, and nutrient export associated with residential development.

Congenital aortic valve anomaly. Aortic regurgitation with left coronary artery isolation.

A case is reported of aortic regurgitation resulting from a congenitally abnormal aortic valve. The left coronary cusp of the valve was small and adhered to the aortic wall, so that there was insufficient valve tissue to maintain diastolic valve competence. In addition, this rudimentary cusp completely occluded the left coronary ostium. The patient was treated successfully by valve replacement.