OREGON CHRISTMAS TREES
The field used to represent Christmas tree production in Oregon is located in Benton County, in the Willamette Valley. According to the 1997 Census of Agriculture, Oregon is the leading producer of Christmas trees in the U.S. with approximately 8 million trees harvested each year. More than a dozen varieties of trees are produced in the region; Douglas fir represents about half of the Pacific Northwest Production. Tree production is a long-term investment with average size trees requiring approximately 7 to 8 years to reach market size (7 to 8 foot). Modern tree operations require intensive site preparation prior to planting, including tillage, soil fertility enhancement and use of cover crops. Tree are mechanically planted in late winter and early spring. Most grower do not have a grass cover crop, but smaller operations keep a mulch grass or living sod in place. Seedlings may be hand planted in difficult or adverse sites or to replace dead trees in first or second year established plantations. Nearly all growers plant 2 to 4-year-old seedlings or 3 to 5-year-old transplants. Trees seldom require irrigation. About 2 to 3 years after planting, trees are sheared or shaped to create the shape of high-quality Christmas trees and to control the amount of annual growth and in some species increase bud set. Nearly all trimming occurs during the summer months based on tree species. Trees are harvested beginning in late October and will continue through mid-December. The soil selected to represent the field is a benchmark soil, Pilchuck fine sand. Pilchuck fine sand is a mixed, mesic Dystric Xeropsamments. The series is mostly pasture and woodland, however, Douglas fir is among the native vegetation. Pilchuck fine sand is a very deep, excessively drained and somewhat excessively drained, rapidly permeable, very slow runoff soil that formed in alluvium. They are found on floodplains at elevations of about 10 to 800 feet above mean sea level on slopes of o to 8 percent. The series is moderately extensive. Pilchuck fine sand is a Hydrologic Group C soil.
|Starting Date||January 1, 1948||Meteorological File - Salem, OR (W24232)|
|Ending Date||December 31, 1983||Meteorological File - Salem, OR (W24232)|
|Pan Evaporation Factor (PFAC)||0.73||PRZM Manual Figure 5.1 (EPA, 1998)|
|Snowmelt Factor (SFAC)||0.16 cm C- 1||PRZM Manual Table 5.1 (EPA, 1998)|
|Minimum Depth of Evaporation (ANETD)||17.0 cm||PRZM Manual Figure 5.2 (EPA, 1998)|
|Method to Calculate Erosion (ERFLAG)||4 (MUSS)||PRZM Manual (EPA, 1998)|
|USLE K Factor (USLEK)||0.373 tons EI-1*||Farm Manual, Table 3.1 (EPA, 1985)|
|USLE LS Factor (USLELS)||0.693.62||Haan and Barfield, 1978|
|USLE P Factor (USLEP)||1.0||Set according to guidance (EPA, 2001)|
|Field Area (AFIELD)||172 ha||Area of Shipman Reservoir watershed (EPA, 1999)|
|NRCS Hyetograph (IREG)||2||PRZM Manual Figure 5.12 (EPA, 1998)|
|Slope (SLP)||4%||Value set to maximum for crop (EPA, 2001)|
|Hydraulic Length (HL)||600 m||Shipman Reservoir (EPA, 1999)|
* EI = 100 ft-tons * in/ acre*hr
|Initial Crop (INICRP)||1||Set to one for all crops (EPA, 2001)|
|Initial Surface Condition (ISCOND)||2||Set to reside prior to new crop planting; forest floor or meadow.|
|Number of Different Crops (NDC)||1||Set to crops in simulation - generally one|
|Number of Cropping Periods (NCPDS)||36||Set to weather data. Salem, OR (W24232)|
|Maximum rainfall interception storage of crop (CINTCP)||0.25||Set to default for orchards (EPA, 2001)|
|Maximum Active Root Depth (AMXDR)||120 cm||Roots can exceed 4 feet,|
|Maximum Canopy Coverage (COVMAX)||40||Based on aerial photography|
|Soil Surface Condition After Harvest (ICNAH)||2||Plantation maintained similar to a coniferous forest|
|Date of Crop Emergence
(EMD, EMM, IYREM)
|15/04||Value set to mid point of planting date (early - mid
Value set to mid point of maturing of 7 - 10 year old trees (late summer)
Value set to mid-point of harvest date (late October)
|Date of Crop Maturity
(MAD, MAM, IYRMAT)
|Date of Crop Harvest
(HAD, HAM, IYRHAR)
|Maximum Dry Weight (WFMAX)||0.0||Set to "0" Not used in simulation|
|SCS Curve Number (CN)||80, 72, 77||Gleams Manual Table A.3, Woodland in poor condition; National Engineering Handbook indicates juniper-grass complexes with loamy texture below surface litter and less than 20 to 25 percent cover have CNs consistent with those selected. (USDA, 1990)|
|Manning's N Value (MNGN)||0.040||RUSLE Project, A12OFOFN Orchard; Full Cover, No-Till, Moderate cover (35-70% residue cover on soil surface during critical period) (USDA, 2000)|
|USLE C Factor (USLEC)||0.006 - 0.041||RUSLE Project; A12OFOFN Orchard; Full Cover, No-Till, Moderate cover (35-70% residue cover on soil surface during critical period) (USDA, 2000)|
|Total Soil Depth (CORED)||150 cm||NRCS, National Soils Characterization Database (NRCS, 2001)|
|Number of Horizons (NHORIZ)||4 (4th extended to 150 cm)|
|First, Second, Third, and Fourth Soil Horizons (HORIZN = 1,2,3,4)|
|Horizon Thickness (THKNS)||
||NRCS, National Soils Characterization Database (NRCS, 2001) http://soils.usda.gov/survey/nscd/|
|Bulk Density (BD)||
|Initial Water Content (THETO)||
|Compartment Thickness (DPN)||
|Field Capacity (THEFC)||
|Wilting Point (THEWP)||
|Organic Carbon Content (OC)|
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).