Super Settlements for a Superfund: A New Paradigm for Voluntary Settlement?

Despite some recent improvements, cleanup of hazardous waste sites across the United States remains slow and very expensive, especially in terms of legal costs. In response to the continuing gridlock, those involved in settlement negotiations at various cleanup sites, including the Environmental Protection Agency, other federal and state government agencies, and private potentially responsible parties (PRPs), are exploring new arrangements of liability and cleanup responsibility under the existing legal and regulatory framework. One emerging response is the “Super Settlement” concept. Under a Super Settlement, a single entity agrees with all, or at least a sufficient preponderance, of the PRPs at a given cleanup site to assume all of their cleanup–related liability in exchange for a fixed and permanent cash–out amount. The Comment examines the Super Settlement concept in light of the current status of federal and state cleanup–related law. The Comment also identifies the trends that have made the concept possible and the issues that remain to be addressed. Finally, the Comment concludes by predicting that the Super Settlement concept will be put into widespread use across the United States as its advantages become better known

Conservation Systems: Effects of Manure Application on Drainage Water Quality

Water table management through the use of artificial subsurface drainage systems is of primary importance in humid areas with poorly or somewhat poorly drained soils to maximize agricultural productivity Excess precipitation in Iowa and many other Mississippi/Ohio River watershed agricultural production states is removed artificially via subsurface drainage systems that intercept and usually divert it to surface waters. Agricultural drainage systems have been installed to allow timely seedbed preparation, planting and harvesting and to protect crops from extended periods of flooded soil conditions. The tradeoff of improved subsurface drainage is a significant increase in the losses of nitrate-nitrogen (Gilliam, et al., 1999). Nitrogen, either applied as fertilizer, or manure or derived from soil organic matter, can be carried as nitrate with the excess water in quantities that can cause deleterious effects downstream. The movement of nitrogen from agricultural fields via drainage waters is a major factor in nonpoint source pollution of surface waters and ultimately the Gulf of Mexico where it has been implicated as a cause of the Hypoxic Zone (Mitsch et al., 2001; Rabalais, et al., 1996). The environmental impacts downstream depend on the agronomic practices implemented, as well as the site, crops, soils and climatological factors. In recent years the use of animal manure, particularly liquid swine manure, in place of commercial fertilizer has increased. From this, the objectives of this study were to compare nitrate-nitrogen losses and crop yield from subsurface drained areas treated with liquid swine manure and commercial fertilizer. Described within are results from two phases (1995-1999 and 2000-2004) of research studying the effects of swine manure on drainage water quality

Nitrification Inhibitor and Nitrogen Application Timing Effects on Yields and Nitrate-Nitrogen Concentrations in Subsurface Drainage from a Corn-Soybean Rotation

Excess precipitation in Iowa and many other agricultural production areas is removed artificially via subsurface drainage systems that intercept and usually divert it to surface waters. Nitrogen, either applied as fertilizer or manure and derived from soil organic matter, can be carried as nitrate with the excess water in quantities that can cause deleterious effects downstream. A four-year, five-replication, field study was initiated in the fall of 1999 in Pocahontas County, Iowa on 0.05 ha plots that are predominantly Nicollet, Webster, and Canisteo clay loams with 3-5% organic matter. The objective was to determine the influence of seasonal N application and the use of nitrapyrin [inhibitor; 2-chloro-6 (trichloromethyl) pyridine] on flow-weighted nitrate-nitrogen concentrations and yields in a corn-soybean rotation, combined on single plots. Six aqua-ammonia nitrogen treatments (168 and 252 kg/ha at planting and in late fall, and 168 kg/ha at planting and late fall with nitrapyrin) were imposed on subsurface drained, continuous-flow-monitored plots. Combined fall 1999 and spring 2000 precipitation was 42% of normal average. Subsequently, normal precipitation was recorded for both fall and spring periods (after fall application, and before spring application) until spring and fall 2002 (51% and 73% of normal, respectively). Spring 2003 precipitation was again only 51% of normal average. Four-year average, flow-weighted nitrate-nitrogen concentrations ranked in highest to lowest order: spring-252(22.9 mg/L;a) \u3e fall-252(18.1 mg/L;b) \u3e spring-168 w/inhibitor(17.7 mg/L;bc) \u3e fall-168 w/inhibitor(16.0 mg/L;bcd) \u3e spring-168(14.8 mg/L;cd) \u3e fall-168(14.2 mg/L;cd). Spring application plots had significantly greater soybean yield the following season compared to fall applications. Greatest corn yields were observed for the spring-252 and fall-168 rates, but were only significantly different than the spring-168 rate for yield. Therefore, under slightly dry to normal precipitation conditions, corn yields and nitrate-nitrogen concentrations in subsurface drainage were not significantly different between seasonal timing or inhibitor use treatments at the 168 kg/ha nitrogen rate

Water Balance Investigation of Drainage Water Management in Non-Weighing Lysimeters

Artificial subsurface drainage systems are often used throughout the upper Midwest to remove excess precipitation and improve crop production. However, these drainage systems export nitrate-nitrogen (NO3-N) to downstream water resources. Management practices are needed to reduce this export of NO3-N with subsurface drainage water. One such practice being considered is the use of drainage water management where subsurface water is held in the soil profile during portions of the year. Previous research has shown that drainage water management has potential to reduce subsurface drainage volume but there is still a need to understand the performance of the practice and the pathways of water flow under varying conditions. The objectives of this study, therefore, were to quantify the pathways of water movement for conventional or free drainage (FD) and drainage water management (DWM) during the growing season. In this study, six non-weighing lysimeters (0.92 × 2.30 m) with a depth of 120 cm were monitored over a 3-yr period under natural and simulated rainfall conditions. The objectives were performed to measure the effects of drainage water management (DWM) on surface runoff, subsurface drainage, and crop yield. The in-season data from natural rainfall conditions showed that DWM reduced subsurface drainage by approximately 14%. The simulated rainfall data showed that DWM increased surface runoff by 54% when the water table was established at 90 cm below the soil surface, and by 87% when the water table was established at 60 cm below the soil surface. Overall DWM was found to have the potential to reduce subsurface drainage but there is the potential that at least a portion of this reduction may be reflected in an increase in surface runoff

Impact of Fertilizer Application Timing on Drainage Nitrate Levels

Nitrate loss from drainage systems in Iowa and other upper Midwestern states is a concern relative to local water supplies as well as the hypoxic zone in the Gulf of Mexico. As a result, there is a need to quantify how various nitrogen management practices impact nitrate loss. One practice that is commonly mentioned as a potential strategy to reduce nitrate loss is to vary fertilizer application timing and specifically apply nitrogen as close to when the growing crop needs it as possible. At a site in Gilmore City, Iowa, a number of fertilizer timing and rate schemes within a corn soybean rotation were used to study the impacts on nitrate leaching. Timing schemes include nitrogen application in the fall and an early season sidedress in the spring with each scheme having four replicates for both corn and soybeans. Fertilizer application rates investigated are 84 and 140 kg/ha (75 and 125 lb/ac) in the fall and 84 and 140 kg/ha (75 and 125 lb/ac) in the spring. The timing and rates have been practiced since 2005 with contrasting weather conditions each year. Overall, an annual basis there was not significant differences in nitrate concentrations or loss exiting the drainage system between the application rates or between the fall and spring application. In addition, there was not a yield penalty to the corn crop when fertilizer as applied in the fall versus the spring

Comparison of Liquid Swine Manure and Aqua-Ammonia Nitrogen Application Timing on Subsurface Drainage Water Quality in Iowa

In Iowa and many other Midwestern states, excess water is removed artificially through subsurface drainage systems. While these drainage systems are vital for crop production, nitrogen (N), added as manure or commercial fertilizer, or derived from soil organic matter, can be carried as nitrate-nitrogen (NO3-N) to downstream water bodies. A five-year, five-replication, field study was initiated in the fall of 1999 in Pocahontas County, Iowa, on 0.05 ha plots that are predominantly Nicollet, Webster, and Canisteo clay loams with 3% to 5% organic matter located on glacial till within the Des Moines Lobe. The objective was to determine the influence of seasonal N application as ammonia or liquid swine manure on flow-weighted NO3-N concentrations and losses in subsurface drainage water and crop yields in a corn-soybean rotation. Four aqua-ammonia N treatments (168 or 252 kg N ha-1 applied for corn in late fall or as an early season side-dress) and three manure treatments (218 kg N ha-1 for corn in late fall or spring or 168 kg N ha-1 in the fall for both corn and soybean) were imposed on subsurface-drained, continuous flow-monitored plots. Precipitation during the drainage season (March to November) was slightly below the long-term norm (722 mm) for all four years in the study period and ranged from 615 mm in 2001 (85% of normal) to 707 mm (98% of normal) in 2004. Monthly rainfall was highly variable, and subsurface drainage, or the lack thereof, usually mimicked the precipitation patterns. On average, 69% of subsurface drainage occurred in May and June of each year, with lower amounts in April and July. Four-year average flow-weighted NO3-N concentrations measured in drainage water were ranked: spring aqua-ammonia 252 (23 mg L-1) = fall manure 168 every year (23 mg L-1) \u3e fall aqua-ammonia 252 (19 mg L-1) = spring manure 218 (18 mg L-1) = fall manure 218 (17 mg L-1) \u3e spring aqua-ammonia 168 (15 mg L-1) = fall aqua-ammonia 168 (14 mg L-1). Corn yields were significantly greater (p = 0.05) for the spring and fall manure 218 rates than for non-manure treatments. Soybean yields were significantly greater (p = 0.05) for the treatments with a spring nitrogen application to the previous corn crop. Overall, under the slightly dry to normal precipitation conditions of this study, corn yields and NO3-N concentrations in subsurface drainage were not significantly different (p = 0.05) between fall and spring treatments at the 168 aqua-ammonia or 218 kg ha-1 N manure N rates

Nitrogen Application Rate Effect on Nitrate-Nitrogen Concentration and Loss in Subsurface Drainage for a Corn-Soybean Rotation

Excess precipitation in Midwest agricultural production areas is often removed artificially via subsurface drainage systems that intercept and divert it to surface waters. Nitrogen (N), either applied as fertilizer or manure or derived from soil organic matter, can be carried as nitrate with the excess water in quantities that may have deleterious effects downstream. A field study was initiated in 1989 in Pocahontas County, Iowa, on 0.05 ha plots of glacially derived clay loams. The objective of this three-phase study was to determine the effect of N application rate on NO3-N concentration and loss in a corn-soybean rotation over a wide range of weather conditions. Nitrogen-rate treatment phases with five seasons each (six for phase II) were imposed on subsurface-drained, continuous-flow-monitored plots over a 16-year period. Phase I N rates ranged from 0 to 168 kg N ha-1 in 56 kg N ha-1 increments. Separate plots were used for each crop in phase I, and significant NO3-N concentration differences were not observed between corn or soybean plots; this led to combining both crops in a split-plot configuration for phases II and III to study system effects. Phase II N rates ranged from 45 to 179 kg N ha-1 in 45 kg N ha-1 increments. Phase III was limited to two rates, 168 and 252 kg N ha-1. Average yearly flow-weighted NO3-N concentrations ranged from 3.9 mg L-1 (45 kg N ha-1, 1995) to 28.7 mg L-1 (252 kg N ha-1, 2001). Average flow-weighted NO3-N concentrations (in mg L-1) ranked by N rate were: 23.4 (252), 13.2 (179), 15.5 (168), 11.9 (134), 11.7 (112), 8.1 (90), 9.5 (56), 5.7 (45), and 8.9 (0). Losses were precipitation dependent and were reflective of individual seasons and rates imposed. Average flow-weighted NO3-N losses (kg ha-1) ranked by N rate and by phase were: 58 (168), 68 (112), 48 (56), 50 (no N) for phase I; 8 (179), 15 (134), 19 (90), 7 (45) for phase II; and 49 (252), 32 (168) for phase III. Results indicate that concentrations generally increased with rate; the effect on losses was variable due to disparity in drainage volumes among years. Corn yield during all periods showed a strong correlation between N rate and yield. As N rate increased, yield increased. It should be noted that at least 50% of the years showed limited yield response to N application above the next to the highest rates. To achieve average NO3-N concentrations less than 10 mg L-1 (USEPA drinking water standard) in subsurface drainage at this site, N application rates would need to be less than 112 kg N ha-1. Rates currently recommended for this area range from 112 to 168 kg N ha-1. Results from this study have significant implications for N fertilizer management and subsurface drainage NO3-N loss to surface waters in the state, the Mississippi River, and the Gulf of Mexico

Effect of different land covers on nitrate-nitrogen leaching and nitrogen uptake in Iowa

Nitrate-nitrogen (NO 3 -N) loading from subsurface drainage is an environmental concern in the Midwest. The majority of NO 3 -N loading occurs in April, May and June when the crops are not planted or just establishing. In this study, NO 3 -N leaching was monitored under alternative land covers and in a corn-soybean rotation. Land cover treatments in a 2-year field experiment included: 1) corn-soybean rotation initiated with corn in 2006 and fallow in late fall and early spring (fallow-Corn-fallow-Soybean, fCfS); 2) corn-soybean rotation initiated with soybean in 2006 and fallow in late fall and early spring (fallow-Soybean-fallow-Corn, fSfC); 3) corn-soybean rotation initiated with corn in 2006 with rye cover crop (rye-Corn-rye-Soybean, rCrS); 4) corn-soybean rotation initiated with soybean in 2006 with rye cover crop ( rye-Soybean-rye-Corn, rSrC); 5) Corn with established kura clover as a living mulch (kura-Kura-kura-Corn, kKkC); and 6) Pasture as a perennial grass treatment (PP). Subsurface drainage volume and NO 3 -N concentration were monitored. Suction lysimeters were installed to extract the soil water solution for NO 3 -N analysis. Biomass of spring cover crops was sampled to analyze nitrogen (N) content. The objectives of this study were: 1) to determine NO 3 -N loss through subsurface drainage as affected by different land covers; 2) to investigate the NO 3 -N concentrations in the soil water under different land covers and 3) to quantify the nitrogen uptake by different cover crops in the spring. The results from the two-year study indicated that the annual average NO 3 -N loss for fCfS and fSfC treatments was 37.5 kg N ha -1 and that the rCrS and rSrC treatments reduced NO 3 -N leaching by 3.8 kg N ha -1 during April, May and June. kKkC and PP treatments resulted in 39.7% and 59.9% annual NO 3 -N leaching reduction, respectively, when compared to the average NO 3 -N loss of fCfS and fSfC treatments. Rye followed by soybean reduced the NO 3 -N concentration in the soil solution significantly (56.4%) at the 30- and 60-cm depths, and PP treatment showed the lowest NO 3 -N concentration at those two depths. The average nitrogen uptake by rye was 33.3 kg N ha -1 at growth termination, and the average N uptake was 59.9 kg N ha -1 for kura clover and 33.2 kg N ha -1 for pasture in early June. This study suggested that winter rye cover crop, kura clover as a living mulch and perennial pasture land covers have positive effects on NO 3 -N loss reduction under the weather condition encountered during this study period in Iowa