OREGON GRASS FOR SEED
The field used to represent grass for seed production in Oregon is located in Linn County, in the Willamette Valley. According to the 1997 Census of Agriculture, Oregon is ranked 1st in cool season forage and turf grass seed production in the U.S. Most of the acreage is located in the Willamette Valley. Oregon's Willamette Valley produces nearly all the ryegrass, perennial ryegrass, bentgrass, and fine fescue grown in the U.S. The crop is seeded in rows using carbon band seeding to protect the crop during emergence. Seed is planted in the early Fall using specialized equipment to overcome the soil conditions call swampbuggies. The soils tend to be poorly draining which are extensive in the Willamette Valley. Harvest begins in late June or early July. After harvest, field burning is used to control disease prior to the next crop. Field burning remains a controversial practice in the region. The soil selected to simulate the field is a benchmark soil, Dayton silt loam. Dayton silt loam, is a fine, smectitic, mesic Vertic Albaqualfs. The series is used to produce spring grains, grass seed, hay and pasture. A small amount is use for vegetable production. Dayton silt loam is a very deep, poorly drained, very slowly permeable soil with slow runoff or ponded conditions. These soils formed in stratified glacio lacustrine deposits of the Pleistocene age. They are found on nearly level or somewhat concave, slightly depressed parts of broad valley terraces at elevations of 150 to 400 feet above mean sea level on slopes of 0 to 2 percent. The series is extensive in the Willamette Valley. Dayton silt loam 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)||0.15 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)||0.43 tons EI-1*||GLEAMS Manual, Table of Representative Soils (USDA, 1990)|
|USLE LS Factor (USLELS)||0.173||GLEAMS Manual, Table of Representative Soils (USDA, 1990)|
|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)||1%||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)||60 cm||http://www.sjrcd.org/ag/effective_root_zone.htm|
|Maximum Canopy Coverage (COVMAX)||100||Set to full canopy for grasses|
|Soil Surface Condition After Harvest (ICNAH)||1||Due to field burning, set to conservative input assuming field fallow until next crop.|
|Date of Crop Emergence
(EMD, EMM, IYREM)
|Date of Crop Maturity
(MAD, MAM, IYRMAT)
|15/05||Set one weeks before harvest, no specific data available.|
|Date of Crop Harvest
(HAD, HAM, IYRHAR)
|Maximum Dry Weight (WFMAX)||0.0||Set to "0" Not used in simulation|
|SCS Curve Number (CN)||84, 79, 82||GLEAMS Table A-3; Meadow; good hydrologic condition (USDA, 1990)|
|Manning's N Value (MNGN)||0.014||RUSLE Project; A12WSHLC; Wheat, Spring pnw 40; Conventional tillage, Portland, OR (USDA, 2000)|
|USLE C Factor (USLEC)||0.026 - 0.459||RUSLE Project; A12WSHLC; Wheat, Spring pnw 40; Conventional tillage, Portland, 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).