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The field used to represent alfalfa production in North Carolina is located in Western North Carolina. According to the 1997 Census of Agriculture, North Carolina is not a major producer of alfalfa (not among the top 20 producing states) 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; alfalfa is not irrigated in North Carolina. Cuttings range from 2 to 4 per year. Most farmers take the last cutting of the season in 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 Helena sandy loam. Helena sandy loam, is a fine, mixed, semiactive, thermic, Aquic Hapludults. Much of these soils are under cultivation in tobacco, corn soybeans, small grains, and vegetable. Helena sandy loam is a very deep, moderately well drained, slowly permeable soil with medium to rapid runoff. These soils formed in residuum weathered from a mixture of felsic, intermediate, or mafic igneous or high grade metamorphic rocks. They are found on broad ridges and toeslopes of the Piedmont uplands on slopes of 2 to 10 percent, but can range from 0 to 15 percent. Helena sandy loam is a Hydrologic Group C soil.

Table 1.
PRZM 3.12 Climate and Time Parameters for Western North Carolina - Alfalfa
Starting Date January 1, 1948Meteorological File - Bristol, TN (W13877)
Ending Date December 31, 1983Meteorological File - Bristol, TN (W13877)
Pan Evaporation Factor (PFAC) 0.76PRZM Manual Figure 5.1 (EPA, 1998)
Snowmelt Factor (SFAC) 0.25 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 Western North Carolina - Alfalfa
Method to Calculate Erosion (ERFLAG) 4 (MUSS)PRZM Manual (EPA, 1998)
USLE K Factor (USLEK) 0.29 tons EI-1*FARM Manual, Table 3.1 (EPA, 1985)
USLE LS Factor (USLELS) 1.34Haan and Barfield, 1978.
USLE P Factor (USLEP) 0.50Set according to guidance (EPA, 2001)
Field Area (AFIELD) 172 haArea of Shipman Reservoir watershed (EPA, 1999)
NRCS Hyetograph (IREG) 3PRZM Manual Figure 5.12 (EPA, 1998)
Slope (SLP) 6%Value mid-point of series slope range (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 Western North Carolina - Alfalfa
Initial Crop (INICRP) 1Set to one for all crops (EPA, 2001)
Initial Surface Condition (ISCOND) 1Set to fallow prior to new crop planting.
Number of Different Crops (NDC) 1Set to crops in simulation - generally one
Number of Cropping Periods (NCPDS) 36Set to weather data. Bristol, TN (W13877)
Maximum rainfall interception storage of crop (CINTCP) 0.25PRZM, Table 5.4 (EPA, 1998)
Maximum Active Root Depth (AMXDR) 100 cmSet to maximum soil depth. Roots may grow to 20 feet.
Maximum Canopy Coverage (COVMAX) 100Set to default for row crops (EPA, 2001)
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.
Date of Crop Emergence

http://forage.cas.psu.edu/docs/species/alfalfa.html Exit EPA Disclaimer
http://forages.orst.edu/IS/NAIS/default.cfm Exit EPA Disclaimer

NC has both Fall and Spring plantings. Set to Spring planting period using mid-point dates. Emergence 7-10 days after planting. Maturation occurs approximately 60 days after planting. Three and sometimes 4 cuttings per season. Harvest set to last event assuming 4 cuttings since Fall planting begins late August early Sept. in NC. Each cutting may occur 28-30 days after last.

Date of Crop Maturity
Date of Crop Harvest
Maximum Dry Weight (WFMAX) 0.0Set to "0" Not used in simulation
SCS Curve Number (CN) 87, 83, 86 Gleams Manual Table A.3, pasture/range, non-CNT, poor condition (USDA, 1990)
Manning's N Value (MNGN) 0.110 RUSLE Project, NB0PWPWN; Pasture, warm-season, no-till, Asheville, NC (USDA, 2000)
USLE C Factor (USLEC) 0.004 RUSLE Project; NB0PWPWN; Pasture, warm-season, no-till, Asheville, NC (USDA, 2000)

Table 4.
PRZM 3.12 Helena Soil Parameters for Western North Carolina - Alfalfa
ParameterValue Verification Source
Total Soil Depth (CORED) 100 cm NRCS, National Soils Characterization Database (NRCS, 2001)
Number of Horizons (NHORIZ) 4 (Top horizon split in two)
First, Second, Third and Fourth Soil Horizons (HORIZN = 1,2,3,4)
Horizon Thickness (THKNS)
  • 10 cm (HORIZN = 1)
  • 20 cm (HORIZN = 2)
  • 18 cm (HORIZN = 3)
  • 52 cm (HORIZN = 4)
NRCS, National Soils Characterization Database (NRCS, 2001) http://soils.usda.gov/survey/nscd/ Exit EPA Disclaimer
Bulk Density (BD)
  • 1.55 g cm-3 (HORIZN = 1,2)
  • 1.51 g cm-3 (HORIZN = 3)
  • 1.5 g cm-3 (HORIZN = 4)
Initial Water Content (THETO)
  • 0.153 cm3-H2O cm3-soil (HORIZN =1,2)
  • 0.250 cm3-H2O cm3-soil (HORIZN =3)
  • 0.322 cm3-H2O cm3-soil (HORIZN =4)
Compartment Thickness (DPN)
  • 0.1 cm (HORIZN = 1)
  • 1 cm (HORIZN = 2,3)
  • 2.0 cm (HORIZN = 4)
Field Capacity (THEFC)
  • 0.153 cm3-H2O cm3-soil (HORIZN = 1,2)
  • 0.250cm3-H2O cm3-soil (HORIZN = 3)
  • 0.322 cm3-H2O cm3-soil (HORIZN = 4)
Wilting Point (THEWP)
  • 0.053 cm3-H2O cm3-soil (HORIZN = 1,2)
  • 0.120 cm3-H2O cm3-soil (HORIZN = 3)
  • 0.192 cm3-H2O cm3-soil (HORIZN = 4)
Organic Carbon Content (OC)
  • 1.16% (HORIZN = 1,2)
  • 0.174 (HORIZN = 3)
  • 0.116% (HORIZN = 4)

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. 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).

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