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The field used to represent apple production in Pennsylvania is located in Lancaster County, in south-eastern Pennsylvania. According to the 1997 Census of Agriculture, Pennsylvania is ranked 5th in apple production in the U.S. Within row tree spacing depends on the root stock and cultivation method. Spacing ranges from as little as 5 feet to 25 feet. Row spacing may be as much as twice the within row spacing to allow for maintenance and harvesting equipment. The soil selected to simulate the field is a benchmark soil, Elioak silt loam. Elioak silt loam, is a clayey, kaolinitic, mesic, Typic Hapludults. The soil is used for pastures, orchards, general local crops and non- agricultural uses. Elioak silt loam is a very deep, well drained, moderately permeable soil with medium to rapid runoff. These soils formed in residuum weathered from mica schists and phyllites, and to a minor extent from granitized schist and micaeous gneiss. They are found on summits and upper slopes in northern portions of the Piedmont Plateau. Most slopes are less than 15 percent, but can range from 0 to 30 percent. The series is of moderate extent in the mid-Atlantic Piedmont Plateau. Elioak silt loam is a Hydrologic Group C soil.

Table 1.
PRZM 3.12 Climate and Time Parameters for Lancaster, PA - Apples
Starting Date January 1, 1948Meteorological File - Allentown, PA (W14737)
Ending Date December 31, 1983Meteorological File - Allentown, PA (W14737)
Pan Evaporation Factor (PFAC) 0.76PRZM Manual Figure 5.1 (EPA, 1998)
Snowmelt Factor (SFAC) 0.2 cm C- 1PRZM Manual Table 5.1 (EPA, 1998)
Minimum Depth of Evaporation (ANETD) 17.0 cmPRZM Manual Figure 5.2 (EPA, 1998)

Table 2.
PRZM 3.12 Erosion and Landscape Parameters for Lancaster, PA - Apples
Method to Calculate Erosion (ERFLAG) 4 (MUSS)PRZM Manual (EPA, 1998)
USLE K Factor (USLEK) 0.42 tons EI-1*PRZM Manual, Table 3.1 (EPA, 1985)
USLE LS Factor (USLELS) 3.60Haan and Barfield, 1978
USLE P Factor (USLEP) 1.0PRZM Table 5.6 (EPA, 1998)
Field Area (AFIELD) 172 haArea of Shipman Reservoir watershed (EPA, 1999)
NRCS Hyetograph (IREG) 3PRZM Manual Figure 5.12 (EPA, 1998)
Slope (SLP) 12%Value set to maximum for crop (EPA, 2001)
Hydraulic Length (HL) 600 mShipman Reservoir (EPA, 1999)

* EI = 100 ft-tons * in/ acre*hr

Table 3.
PRZM 3.12 Crop Parameters for Lancaster, PA - Apples
Initial Crop (INICRP) 1Set to one for all crops (EPA, 2001)
Initial Surface Condition (ISCOND) 3Orchard - material is largely left in place
Number of Different Crops (NDC) 1Set to crops in simulation - generally one
Number of Cropping Periods (NCPDS) 36Set to weather data. Allentown, PA (W14737)
Maximum rainfall interception storage of crop (CINTCP) 0.25Set to default for orchards (EPA, 2001)
Maximum Active Root Depth (AMXDR) 100 cmSet to maximum soil depth. Roots may grow to 20 feet.
Maximum Canopy Coverage (COVMAX) 90 http://caf.wvu.edu/kearneysville/fruitloop.html Exit EPA Disclaimer
Ross Byers, Horticultural Specialist VPI - canopy somewhat open between rows; 90% reasonable upper end estimate.
Soil Surface Condition After Harvest (ICNAH) 3Orchards floor maintained similar to a meadow
Date of Crop Emergence
20/04 Personal communication w/ Ross Byers, VA Tech Fruit Horticulturalist (540) 869-2560 x19
Emergence based on leaf emergence, Maturation based on canopy maturity, Harvest based on average leaf fall. Dates based on central VA and modified by: 1 day added for every 100 miles north or 100 feet higher elevation or 1day subtracted for every 100 miles south or 100 feet lower elevation.
Date of Crop Maturity
Date of Crop Harvest
Maximum Dry Weight (WFMAX) 0.0Set to "0" Not used in simulation
SCS Curve Number (CN) 84, 79, 82Gleams Manual Table A.3, meadow; condition good (USDA, 1990)
Manning's N Value (MNGN) 0.014 RUSLE Project, SB5OBOBC; Orchards, bare ground; conventional tillage; York, PA (USDA, 2000)
USLE C Factor (USLEC) 0.103 - 0.515 RUSLE Project; SB5OBOBC; Orchards, bare ground; conventional tillage; York, PA (USDA, 2000)

Table 4.
PRZM 3.12 Elioak Soil Parameters for Lancaster, PA - Apples
ParameterValue Verification Source
Total Soil Depth (CORED) 100 cm NRCS, National Soils Characterization Database (NRCS, 2001)
Number of Horizons (NHORIZ) 3 (Top horizon split in two)
First, Second, and Third Soil Horizons (HORIZN = 1,2,3)
Horizon Thickness (THKNS)
  • 10 cm (HORIZN = 1)
  • 28 cm (HORIZN = 2)
  • 62 cm (HORIZN = 3)
NRCS, National Soils Characterization Database (NRCS, 2001) http://soils.usda.gov/survey/nscd/ Exit EPA Disclaimer
Bulk Density (BD)
  • 1.70 g cm-3 (HORIZN = 1,2)
  • 1.80 g cm-3 (HORIZN = 3)
Initial Water Content (THETO)
  • 0.218 cm3-H2O cm3-soil (HORIZN =1,2)
  • 0.243 cm3-H2O cm3-soil (HORIZN =3)
Compartment Thickness (DPN)
  • 0.1 cm (HORIZN = 1)
  • 7 cm (HORIZN = 2)
  • 7.75 cm (HORIZN = 3)
Field Capacity (THEFC)
  • 0.218 cm3-H2O cm3-soil (HORIZN = 1,2)
  • 0.243cm3-H2O cm3-soil (HORIZN = 3)
Wilting Point (THEWP)
  • 0.098 cm3-H2O cm3-soil (HORIZN = 1,2)
  • 0.163 cm3-H2O cm3-soil (HORIZN = 3)
Organic Carbon Content (OC)
  • 1.16% (HORIZN = 1,2)
  • 0.174 (HORIZN = 3)

EPA. 1985. Field Agricultural Runoff Monitoring (FARM) Manual, (EPA/600/3-85/043) Environmental Research Laboratory, U.S. Environmental Protection Agency, Athens, GA.

EPA. 1998. Carsel, R.F., J.C. Imhoff, P.R. Hummel, J.M. Cheplick, and A.S. Donigian, Jr. PRZM-3, A Model for Predicting Pesticide and Nitrogen Fate in the Crop Root and Unsaturated Soil Zones: Users Manual for Release 3.0. National Exposure Research Laboratory, Office of Research and Development, U.S. Environmental Protection Agency, Athens, GA.

EPA. 1999. Jones, R.D., J. Breithaupt, J. Carleton, L. Libelo, J. Lin, R. Matzner, and R. Parker. Guidance for Use of the Index Reservoir in Drinking Water Exposure Assessments. Environmental Fate and Effects Division, Office of Pesticide Programs, U.S. Environmental Protection Agency, Washington. D.C.

EPA. 2001. Abel, S.A. Procedure for Conducting Quality Assurance and Quality Control of Existing and New PRZM Field and Orchard Crop Standard Scenarios. Environmental Fate and Effects Division, Office of Pesticide Programs, U.S. Environmental Protection Agency, Washington, D.C.

Haan, C.T. and B.J. Barfield. 1978. Hydrology and Sedimentology of Surface Mined Lands. Office of Continuing Education and Extension, College of Engineering, University of Kentucky, Lexington, Kentucky 40506. pp. 286.

USDA. 1990. Davis, F.M., R.A. Leonard, W.G. Knisel. GLEAMS User Manual, Version 1.8.55. USDA-ARS Southeast Watershed Research Laboratory, Tifton GA. SEWRL-030190FMD.

USDA. 2000. Revised Universal Soil Loss Equation (RUSLE) EPA Pesticide Project. U.S. Department of Agriculture, National Resources Conservation Service (NRCS) and Agricultural Research Service (ARS).

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