The field used to represent alfalfa production in Minnesota is located in Polk County in the Red River Valley, however, alfalfa is produced throughout the state. According to the 1997 Census of Agriculture, Minnesota ranked 6th in production of alfalfa in the U.S. Alfalfa is a perennial crop, grown on a variety of soils, planted early in the year and maintained under continuous cultivation on a 3- to 5-year cycle at which time a new crop is planted. Planting depths range from 0.25 to 1.0 inches, depending on soil texture, on level seed beds. Row spacing is approximately 30 inches; very little alfalfa is irrigated in Minnesota because of soil conditions and the depth at which roots may grow (up to 20 feet) help make alfalfa drought tolerant. Cuttings range from 2 to 4 per year and most growers harvest alfalfa when the stand is at 10 percent bloom. Most farmers take the last cutting of the season between mid-August and mid-September. Alfalfa prefers well-drained soils with a pH near neutral (pH 6.7-6.9). The soil selected to simulate the field is a benchmark soil, Bearden silty clay loam. Bearden silty clay loam, is a fine-silty, mixed, superactive, frigid Aeric Calciaquolls. These soils are nearly all under cultivation to small grains, especially alfalfa, and row crops. Bearden silty clay loam is a very deep, somewhat poorly drained, slowly permeable soil with negligible to high runoff. These soils formed in calcareous silt loam and silty clay loam lacustrine sediments. They are generally found on glacial lake plains at elevations from 650 to 2000 feet above mean sea level on slopes of 0 to 3 percent. Bearden silty clay loam is a Hydrologic Group C soil.
|Starting Date||January 1, 1948||Meteorological File - Fargo, ND (W14914)|
|Ending Date||December 31, 1983||Meteorological File - Fargo, ND (W14914)|
|Pan Evaporation Factor (PFAC)||0.75||PRZM Manual Figure 5.1 (EPA, 1998)|
|Snowmelt Factor (SFAC)||0.5 cm C- 1||PRZM Manual Table 5.1 (EPA, 1998)|
|Minimum Depth of Evaporation (ANETD)||12.0 cm||PRZM Manual Figure 5.2 (EPA, 1998)|
|Method to Calculate Erosion (ERFLAG)||4 (MUSS)||PRZM Manual (EPA, 1998)|
|USLE K Factor (USLEK)||0.28 tons EI-1*||GLEAMS Manual, table of Representative Soils (USDA, 1990)|
|USLE LS Factor (USLELS)||0.17||GLEAMS Manual, table of Representative Soils (USDA, 1990)|
|USLE P Factor (USLEP)||0.50||Set according to guidance (EPA, 2001)|
|Field Area (AFIELD)||172 ha||Area of Shipman Reservoir watershed (EPA, 1999)|
|NRCS Hyetograph (IREG)||3||PRZM Manual Figure 5.12 (EPA, 1998)|
|Slope (SLP)||1.5%||Value mid-point of series slope range (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 fallow prior to new crop planting. http://pestdata.ncsu.edu/cropprofiles|
|Number of Different Crops (NDC)||1||Set to crops in simulation - generally one|
|Number of Cropping Periods (NCPDS)||36||Set to weather data. Fargo, ND (W14914)|
|Maximum rainfall interception storage of crop (CINTCP)||0.25||PRZM, Table 5.4 (EPA, 1998)|
|Maximum Active Root Depth (AMXDR)||100 cm||Set to maximum soil depth. Roots may grow to 20 feet http://pestdata.ncsu.edu/cropprofiles|
|Maximum Canopy Coverage (COVMAX)||100||Dr. Mohamed Kahn; NDSU (701) 231-8596; Larry Smith U of MN (218) 281-8602.|
|Soil Surface Condition After Harvest (ICNAH)||3||Set to residue for winter months after last harvest during multi-year growth and during winter of last years of growth http://pestdata.ncsu.edu/cropprofiles|
|Date of Crop Emergence
(EMD, EMM, IYREM)
|27/05||Usual Planting and Harvesting Dates for U.S. Field Crops (USDA, 1984)|
|Date of Crop Maturity
(MAD, MAM, IYRMAT)
|25/08||Usual Planting and Harvesting Dates for U.S. Field Crops (USDA, 1984)|
|Date of Crop Harvest
(HAD, HAM, IYRHAR)
|30/08||Usual Planting and Harvesting Dates for U.S. Field Crops (USDA, 1984)|
|Maximum Dry Weight (WFMAX)||0.0||Set to "0" Not used in simulation|
|SCS Curve Number (CN)||85, 81, 83||Gleams Manual Table A.3, Close-seed legumes SR/poor; Cropping and Residue = Close-seed legumes, SR/good condition (USDA, 1990)|
|Manning's N Value (MNGN)||0.110||RUSLE Project, F86HLHLC; Hay, Legumes, Conventional tillage, Glasgow, MN (USDA, 2000)|
|USLE C Factor (USLEC)||0.001 - 0.010||RUSLE Project; F86HLHLC; Hay, Legumes, Conventional tillage, Glasgow, MN (USDA, 2000)|
|Total Soil Depth (CORED)||100 cm||NRCS, National Soils Characterization Database (NRCS, 2001)|
|Number of Horizons (NHORIZ)||4 ( 3 Base Horizons with top horizon split in two)|
|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. 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.
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. 1984. Usual Planting and Harvesting Dates for U.S. Field Crops, Statistical Reporting Service, U.S. Department of Agriculture, Agriculture Handbook #628, pp.78.
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).