OREGON WHEAT (Winter)
The field used to represent wheat production in Oregon is located in the Willamette Valley. According to the 1997 Census of Agriculture, Oregon is ranked 8th in wheat production in the U.S. The crop is generally planted in the Fall (September) and harvested the following year beginning in July. Row spacing ranges from 6 to 9 inches with seeds planted at a depth of 2 inches or less. The soil selected to simulate the field is a benchmark soil, Bashaw clay. Bashaw clay is a very-fine, smectitic, mesic Xeric Endoaquerts. The series is used to produce spring grains which the remainder in natural vegetation. Bashaw clay is a very deep, poorly drained, very slowly permeable soil with an apparent water table at 1 foot above to 0.5 feet below the surface from November to May. Unless protected, flooding is common from December to April. These soils formed in fine textured alluvium. They are found on nearly level or somewhat concave flood plains and terraces and gently sloping fans at elevations of 90 to 1,000 feet above mean sea level on slopes of 0 to 12 percent. The series occur in small bodies and is inextensive in the Willamette Valley. Bashaw clay is a Hydrologic Group D 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)||0.74||PRZM Manual Figure 5.1 (EPA, 1998)|
|Snowmelt Factor (SFAC)||0.36 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)||0.13 tons EI-1*||FARM Manual, Table 3.1 (EPA, 1985)|
|USLE LS Factor (USLELS)||1.34||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)||6%||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)||1||Set to residue prior to new crop planting|
|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)||0.1||PRZM Manual, Table 5.4 (EPA, 1998)|
|Maximum Active Root Depth (AMXDR)||23 cm||PRZM Input Collator, PIC (Burns, 1992); PRZM Table 5.9 (EPA, 1998)|
|Maximum Canopy Coverage (COVMAX)||100||PRZM Input Collator, PIC (Burns, 1992)|
|Soil Surface Condition After Harvest (ICNAH)||1||Set to conservative input assuming field fallow until next crop. Residue removed with crop harvest.|
|Date of Crop Emergence
(EMD, EMM, IYREM)
|01/09||Emergence based on 15 days from planting; customary planting in OR between Sept 1-15 (USDA, 1984) |
Maturation based on 220 day average; PRZM Table 5.9
Harvest based on Usual Planting and Harvesting Dates for U.S. Field Crops (USDA, 1984)
|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)||92, 89, 90||GLEAMS Table A-3; Close-seeded legumes Fallow = Fallow ST/CT/poor; Cropping and Residue = SR, conventional tillage, poor condition (USDA, 1990)|
|Manning's N Value (MNGN)||0.023||RUSLE Project; A13WWHLC; Winter wheat, conventional tillage, Salem, OR (USDA, 2000)|
|USLE C Factor (USLEC)||0.017 - 0.336||RUSLE Project; A13WWHLC; Winter wheat, conventional tillage, Salem, OR (USDA, 2000)|
|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)||
||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).