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Best management practices (BMPs) have been implemented on a farm-by-farm basis within the Cannonsville Reservoir watershed (CRW) as part of a New York City watershed-wide BMP implementation effort to reduce phosphorus (P) loads to the water supply reservoirs. Monitoring studies have been conducted at selected locations and at the watershed outlet on one of the farms, which spans an entire subwatershed within the CRW, with the aim of quantifying effectiveness of the BMPs installed on the farm. This study applied the Soil and Water Assessment Tool (SWAT) and a recently developed BMP characterization tool to the farm over pre- and post-BMP installation periods with the object of determining the extent to which model results incorporating all installed BMPs match observed data, and the individual impact of each of the BMPs installed on the farm. The SWAT model generally performed well at the watershed level for flow, sediment, and phosphorus simulations. Annual Nash-Sutcliffe (NS) coefficients for the components ranged between 0.56 and 0.80, while monthly NS coefficients ranged between 0.45 and 0.78. The model also performed well at the field level, with simulated in-field P loads closely matching observed data. Because the fields had various combinations of BMPs installed on them, it was difficult to separate out individual BMP impacts based on SWAT simulations. It was, however, possible to determine the effects of BMP combinations such as nutrient management plans and rotations (31% dissolved P; 25% total P). For dissolved P, integration of BMP tool efficiencies allowed individual BMP impacts to be incorporated while still maintaining the same level of representation as was obtained using model simulations. As the SWAT model is often used with little or no post-BMP data to verify simulation results, this study served to validate SWAT model suitability for evaluating BMP impacts. The BMP tool was found to suitably complement the model by providing insights into individual BMP impacts, and providing BMP efficiency data where the model was lacking. [ABSTRACT FROM AUTHOR]

The chemical and hydrologic responses of a 9.9-ha Pennsylvania hill-land watershed to a typical summer storm event were determined and compared. Patterns and the relative magnitudes of NO3, NH4, total phosphorus (P), and orthophosphate (PO4) concentrations observed in seepage, surface runoff, storm flow, base flow, and rainfall fit those hypothesized from the storm hydrograph and associated water table responses observed in the near-stream zone. Nitrate concentrations in seepage and base flow were similar and, typically, exceeded those in surface runoff, rainfall, and peak storm flow by 5-20 times. Conversely, NH4, total P, and PO4 concentrations in surface runoff from the seep zone and in peak storm flows exceeded those in seepage and base flow by 2-20 times. The findings, presented in a hydrologically based framework for this watershed, provide a conceptual model of how the near-storm zone operates during and following storm events. [ABSTRACT FROM AUTHOR]

A best management practice (BMP) tool was developed as a part of an effort to address the phosphorus (P) pollution and associated eutrophication problem affecting the Cannonsville Reservoir, part of the New York City water supply system. P reaching the reservoir is thought to emanate from runoff from the surrounding farms, mainly as a result of manure spread on these farms. Efforts to address the problem have involved implementation of BMPs on the watersheds; however, the effectiveness of these practices is not known. This study establishes a means of estimating BMP effectiveness, based on data available in the literature, and develops a tool that allows users to obtain BMP effectiveness estimates for their respective site soil and slope conditions. The tool offers stand-alone capabilities and has the potential to be linked to a GIS. An example is presented to illustrate tool application for effectiveness-based BMP selection, with a focus on a farm within the New York City watersheds. [ABSTRACT FROM AUTHOR]

Transport factors incorporated within most versions of the phosphorus index (PI) are expected to represent the potential for phosphorus (P) to be mobilized on the field and subsequently move from the field source to a stream or other surface-water body. Consequently, these factors must be designed to capture the nature of the hydrologic properties of both the field and the watershed. The field-related transport factors typically included in PIs, e.g., the NRCS soil runoff class and erosion loss via RUSLE are generally accepted as sufficient to represent edge-of-field P loss. However, there has not been a unified approach to represent connectivity of field to stream within the PI. Here, we develop a generalized connectivity factor for inclusion in PIs based on design rainfall, the variable-source-area (VSA) hydrologic concept, and readily available watershed geomorphic data. The NRCS curve number method is used to determine runoff volume from the watershed for design rainfalls representing a range of return periods. A simplification of VSA hydrology is used to derive the contributing area from which this runoff is expected to occur. Finally, the width of land adjacent to the stream contributing surface runoff is estimated using drainage density. For illustration, the methodology is applied to a small upland watershed in east-central Pennsylvania, and the results are examined in light of hydrologic investigations being conducted on the watershed. [ABSTRACT FROM AUTHOR]

Nitrate nitrogen (NO3-N) leaching from animal production systems in the northeast USA is a major non-point source of pollutionin the Chesapeake Bay. We conducted a study to measure NO3-N leaching from dairy slurry applied to orchardgrass (Dactylis glomerata L., cv. Pennlate) using large drainage lysimeters to measure the direct impact of four rates of slurry (urine and faeces) N application (0, 168, 336, 672 kg N ha-1 yr-1) on NO3-N leaching on three soil types. We then used experimentally-based relationships developed earlier between stocking density and NO3-N leaching loss and leachate NO3-N concentration to estimate the added impact of animal grazing. Nitrate N leaching losses from only dairy slurry applied at the 0, 158, 336, and 672 kg N ha-1 yr-1 rates were 5.85, 8.26, 8.83, and 12.1 kg N ha-1 yr-1, respectively with corresponding NO3-N concentrations of 1.60, 2.30, 2.46, and 3.48 mg l-1. These NO3-N concentrations met the 10 mgl-1 US EPA drinking water standard. However, when a scenario was constructed to include the effect of NO3-N leaching caused by animal grazing, the NO3-N drinking water standard was calculated to be exceeded. [ABSTRACT FROM AUTHOR]

A field study site was installed in east-central Pennsylvania to examine processes controlling groundwater recharge. It was instrumented to monitor climatic inputs, soil water dynamics and groundwater response. Characterization of the layered fractured bedrock underlying thesite by rock coring, seismic surveys and interval packer testing showed consistencies between layer depths, fracture frequencies, seismicvelocities and hydraulic conductivities. Monthly summaries of rainfall and percolate over two years showed that percolate rates were generally high and closely related to precipitation during the dormant season. During the growing season, however, the relationship became erratic with large variabilities occurring between individual lysimeter measurements. Eight dormant season rainfall events were examined in detail. Smaller events produced similar responses from 1 m deep percolate lysimeters. Approximately 10-15 mm of rain was required to initiate percolate, with the time delay in response dependent on how long it took this depth to accumulate; 5 to 6 mm of the rain was retained in storage, with the remainder becoming percolate. Larger rains, from 30-110 mm, caused correspondingly larger depths of percolate and larger water table responses, but generally similar patterns of site response. Groundwater at the site was typically about 6 m below the land surface during the dormant season. It responded 1-2 hours after the onset of percolate, and reached its maximum elevation anywhere from 4 to 16 hours after that, even though percolate was still occurring. Based on causative depth of recharge and amount of water level rise in wells, the specific yield of the aquifer was found to be of the orderof 0701. This value is characteristic of fracture geometry rather than matrix properties of the bedrock. [ABSTRACT FROM AUTHOR]

The Cannonsville Reservoir watershed is a major component of the unfiltered New York City water supply system. The voluntary, incentive-based Watershed Agricultural Program is a collaborative effort among producers, federal, state, and local organizations to address the problem of phosphorus loading effects on water quality through implementation of whole-farm plans. The effectiveness of selected conservation practices, including stream-bank fencing, precision feeding, and the use of cover crops with silage corn (Zea mays L.) are being evaluated. Simulation models have been developed and improved to evaluate the effectiveness of individual conservation practices and better assess animal agriculture and manure management practices. Conservation practices implemented through the Watershed Agricultural Program are resulting in lower phosphorus loading from nonpoint sources in the watershed. Future efforts need to identify the most cost-effective conservation practices and extend our knowledge of watershed quality protection beyond the boundaries of the Cannonsville Reservoir watershed. [ABSTRACT FROM AUTHOR]

Structural best management practices were implemented throughout the Cannonsville Reservoir Watershed (CRW) in an effort to reduce P losses to the reservoir. Yet long-term water quality control efforts within CRW are hindered by continuous P build-up in the soils resulting from dairy farm P imports exceeding exports. Addressing the P imbalance problems and maintaining economic viability of the farms requires a system-level redesign of farm management. One possible innovative strategy, precision feed management (PFM), reduces soil-P build-up by limiting feed and fertilizer purchases, and increasing high-quality homegrown forage production. This study applied the integrated farm system model (IFSM) to 2 CRW dairy farms to quantify the benefits of a PFM farm planning strategy in controlling P imbalance problems, and maintaining farm profitability and reducing off-farm P losses. The IFSM accurately simulated the 2 farms based on farm data supplied by farm planners; these scenarios were used as the baseline conditions. The IFSM simulations of more accurate feeding of P (based on P required in animal diets) integrated with increased productivity of grass-forage and increased proportion of forage in the diet reduced the P imbalance of 1 farm from 5.3 to 0.5 kg/ha and from 9.6 to 0.0 kg/ha for the second farm. For both farms, soluble P lost to the environment was reduced by 18%. Feed supplement purchases declined by 7.5 kg/cow per year for dietary mineral P, and by 1.04 and 1.29 t/cow per year for protein concentrates through adoption of the PFM system. Moreover, when a land management practice of converting corn to grass was coupled with the precision feeding of P and improved forage management, IFSM predicted reductions of 5.8 and 9.3 kg/ha of converted land sediment-bound P in erosion loss each year. The model predicted slight purchase increases in corn grain to offset reductions in corn silage production and feeding rates, but no appreciable change in the farm P balance due to land conversion. The model-based studies conducted on a farm-by-farm basis complement farm planning efforts in exploring innovative farming systems. Moreover, the results set a benchmark for potential benefits of PFM strategies, economically and environmentally. [ABSTRACT FROM AUTHOR]

Farm management and financial impacts of three phosphorus (P) nutrient management strategies outlined in the U.S. Department of Agriculture (USDA) and U.S. Environmental Protection Agency (USEPA) (1999) Unified Strategy for Animal Feeding Operations--soil test crop response (STCR), environmental soil P threshold (ESPT), and P Index (PI)--were evaluated on ten Pennsylvania farms. For each farm, a nutrient management plan (NMP) writer and project economist developed one nitrogen-based and three P-based NMPs and associated partial budgets. Greater management and financial restrictions occurred on high animal density (> 2 animal equivalent units ac-1) and multiple production enterprise farms. Although NMPs for the PI were more expensive to develop, writers and farmers found it the most flexible and practical strategy. Variable P-based NMP impacts indicated the need for a strategy such as the PI that accounted for multiple farm management factors. First-year total NMP implementation costs (across all ten farms) were $61,690 for the STCR, $47,862 for the ESPT, and $45,380 for the PI. [ABSTRACT FROM AUTHOR]

Long-term accumulation of soil phosphorus (P) is becoming a concern on some watersheds heavily populated with animal feeding facilities, including dairy farms. Management changes in crop production and feeding may help reduce the accumulation of excess P, but farm profitability must be maintained or improved to assure adoption of such changes. Whole-farm simulation was used to evaluate the long-term effects of changes in feeding, cropping, and other production strategies on P loading and the economics of 100-cow and 800-cow dairy farms in southeastern New York. Simulated farms maintained a long-term P balance if the following occurred: 1) animals were fed to meet recommended minimum amounts of dietary P, 2) the cropping strategy and land base supplied all of the forage needed, 3) all animals were fed a high forage diet, and 4) replacement heifers were produced on the farm to utilize more forage. The most easily implemented change was to reduce the supplemental mineral P fed to that required to meet current NRC recommended amounts, and this provided an annual increase in farm profit of about $22/cow. Intensifying the use of grassland and improving grazing practices increased profit along with a small reduction in excess P. Conversion from dairy production to heifer raising or expansion from 100 cows to a 250-cow "state-of-the-art" confinement facility (with a 70% increase in land area) were also profitable options. These options provided a long-term P balance for the farm as long as the production and use of forage was maximized and minimum dietary P amounts were those recommended by the NRC. Thus, management changes can be made to prevent the long-term accumulation of soil P on dairy farms while improving farm profitability.