Gary K. Felton

Evaluation of infiltration models in contaminated landscape

The infiltration models of Kostiakov, Green-Ampt, and Philip (two and three terms equations) were used, calibrated, and evaluated to simulate in-situ infiltration in nine different soil types. The Osborne-Moré modified version of the Levenberg-Marquardt optimization algorithm was coupled with the experimental data obtained by the double ring infiltrometers and the infiltration equations, to estimate the model parameters. Comparison of the model outputs with the experimental data indicates that the models can successfully describe cumulative infiltration in different soil types. However, since Kostiakovs equation fails to accurately simulate the infiltration rate as time approaches infinity, Philips two-term equation, in some cases, produces negative values for the saturated hydraulic conductivity of soils, and the Green-Ampt model uses piston flow assumptions, we suggest using Philips three-term equation to simulate infiltration and to estimate the saturated hydraulic conductivity of soils.

In Vitro and In Vivo Assessment of Aqueously Extractable Estrogens in Poultry Manure after Pilot-scale Composting

Poultry manure contains free and conjugated forms of the natural estrogens 17β-estradiol and estrone, which can be transported to receiving waters via runoff when land-applied. Previous studies have demonstrated estrogens in runoff from poultry manure-amended fields but have not tracked changes in estrogenicity within this water over time. Microbial conversion of conjugated estrogens (a major portion of water-extractable estrogens) to parent forms may result in temporary increases in estrogenicity in natural water bodies. The present study created 80-L batches of simulated poultry manure runoff, which were investigated over 10 d for estrogenicity by bioluminescent yeast estrogen screen assay and fathead minnow () vitellogenin induction model. The efficacy of different compost conditions (in-vessel aeration ± turning, and piling) on reduction/elimination of aqueously extractable estrogens in poultry manure was also investigated. Results indicate 3- to 10-fold increases in estrogenicity in various poultry manure mixtures during 10-d observations. Estrogenicity returned to low levels in postcompost treatments but remained elevated in the precompost treatment. Aerated compost resulted in >75% reductions in initial, peak, and 10-d mean estrogenicity in aqueous mixtures (0.3, 0.8, and 0.5 ng 17β-estradiol equivalents [EEQ] L, respectively) compared with the precompost mixture (1.4, 4.8, and 2.1 ng EEQ L, respectively). Estrogenicity was significantly higher in the aqueous extract from the piled treatment than the aerated treatment, and 10-d exposure of male fish to the piled treatment resulted in statistically significant vitellogenin induction. Collectively, our results suggest a need to investigate estrogenicity in surface waters for several days after receiving manure-influenced runoff.

Nitrogen Migration from Deep-Row Biosolids Incorporation on a Hybrid Poplar Tree Farm

Deep row incorporation of biosolids at rates of 383-658 Mg/ha(171 to 294 dry tons per acre) using hybrid poplar involves the placement of biosolids into trenches that are immediately covered with overburden, eliminating odor problems and maintaining the biosolids in a fairly stable, anaerobic environment. The site is then planted with hybrid poplar trees, the roots of which provide a natural recycling system that utilizes the nutrients over a six-year period in most cases. For three years, nitrate beneath the trenches was essentially zero. Subsequently, nitrate concentration increased to between 1 and 10 mg/L. Ammonium in the suction lysimeters remained between 100-600 mg/L from March 2003 until August 2004, when there was a peak in the highest application rate to 800 mg/L from November 2004 to September 2005. Ammonium concentration is clearly decreasing with distance from the biosolids for all treatments, with significant differences between treatments becoming apparent from November 2003 to November 2005. Ammonium levels in October 2006 at 15 and 60 cm may have stabilized or decreased slightly to 1900 and 400 mg/L, respectively. While ammonium levels at 30 and 60 cm may have leveled off, additional suction lysimeters were installed during the summer of 2007 at 120 cm below the biosolids trench in all plots to better understand ammonium movement in the profile.

Effect of Nitrogen-Based Biosolid Application on Tree Growth, Water Quality, and Soil Phosphorus in Hybrid Poplar Plantations

A three-year study applied four N-based biosolid treatments to hybrid poplar trees over a two year period with spring and fall applications. All biosolid treatments had a faster rate of diameter and biomass growth (but not height) than the control, but the High and Medium application rates had the fastest rate of growth, and were not significantly different. There was no difference in foliar nitrogen and phosphorus levels between any of the treatments. Water quality data from suction lysimeters generated nitrate values below 20 ppm for the low treatment, which is similar to levels found in a cornfield. Four wells surrounding the site reported nitrate levels within the range of values found associated with other eastern shore cropland. P levels in soil samples escalated immediately after broadcast application to levels above the threshold in the state nutrient management regulation. The use of nitrogen based biosolid application in Maryland or other states with similar phosphorus-based nutrient management regulations is not feasible on the soil types tested.

Farmer-Led Climate Change Adaptations for Agro-Ecosystems in the Mid-Atlantic U.S.

Abstract. Data from the National Climatic Data Center indicate that between 1900 and 2010 the mean monthly temperature in Maryland has increased in every month of the year with monthly increases ranging from 0.5 to 2.9°F and a mean monthly increase of 1.7°F (0.9°C) (Table 1) 4 . This rise is consistent with the mean increase in global temperature of about 1.2°Ði reported by the IPCC 1 . The National Weather service data also indicate a fluctuating monthly precipitation 4 , which is significant within the context of crop production.