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CALIFORNIA ALFALFA (Northern and Southern)
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The field used to represent alfalfa production in California is located in San Joaquin County in the Central Valley, although the crop is grown throughout the Central Valley and as far south as the Imperial Valley. According to the 1997 Census of Agriculture, California is ranked 1st in pounds of alfalfa hay harvested and among the top 10 in acres planted. Alfalfa is a perennial crop, planted early in the year and maintained under continuous cultivation on a 4- 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; nearly all alfalfa is irrigated in California by flooding. Cuttings range from 3 to 5 per year under most conditions. Alfalfa prefers well-drained soil with a pH near neutral. Root systems rarely exceed 2 feet in California and cuttings occur when the plant reaches a height of approximately 30 inches. The soil selected to simulate the field is a benchmark soil, Sacramento clay. Sacramento clay, is a very-fine, smectitic, thermic Cumulic Vertic Endoaquolls. These soils are often used for alfalfa cultivation providing the water table is low. Sacramento clay is a poorly to very poorly drained, slowly permeable soil with very slow to slow runoff. These soils formed in fine textured alluvium of mixed origin and are of moderate extent. They are generally found in level basins at elevations near sea level to 60 feet. The soil is typical of soils used for a variety of row crops, rice, safflower and alfalfa. Sacramento clay is a Hydrologic Group D soil.
| Parameter | Value | Source |
|---|---|---|
| Starting Date | January 1, 1948 | Meteorological File - Southern: Bakersfield, CA (W23155) and Northern: Sacramento, CA (W23232) |
| Ending Date | December 31, 1983 | Meteorological File - Southern: Bakersfield, CA (W23155) and Northern: Sacramento, CA (W23232) |
| Pan Evaporation Factor (PFAC) | 0.73 | PRZM Manual Figure 5.1 (EPA, 1998) |
| Snowmelt Factor (SFAC) | 0.45 cm C- 1 | PRZM Manual Table 5.1 (EPA, 1998) |
| Minimum Depth of Evaporation (ANETD) | 15.0 cm | PRZM Manual Figure 5.2 (EPA, 1998) |
| Parameter | Value | Source |
|---|---|---|
| Method to Calculate Erosion (ERFLAG) | 4 (MUSS) | PRZM Manual (EPA, 1998) |
| USLE K Factor (USLEK) | 0.20 tons EI-1* | NRI - Average value listed for the soil series Sacramento |
| USLE LS Factor (USLELS) | 0.19 | NRI - Average value listed for the soil series Sacramento |
| USLE P Factor (USLEP) | 1.00 | NRI - Average value listed for the soil series Sacramento |
| Field Area (AFIELD) | 172 ha | Area of Shipman Reservoir watershed (EPA, 1999) |
| NRCS Hyetograph (IREG) | 1 | PRZM Manual Figure 5.12 (EPA, 1998) |
| Slope (SLP) | 2% | Marcia Campbell-Matthews San Joaquin County Cooperative Extension Agent. 209-468-2085 |
| Hydraulic Length (HL) | 600 m | Shipman Reservoir (EPA, 1999) |
| Irrigation Flag (IRFLAG) | 2 (cropping period only) | Marcia Campbell-Matthews San Joaquin County Cooperative Extension Agent. 209-468-2085 |
| Irrigation Type (IRTYP) | 1 (Flood) | Marcia Campbell-Matthews San Joaquin County Cooperative Extension Agent. 209-468-2085 |
| Leaching Factor (FLEACH) | 0.1 | Marcia Campbell-Matthews San Joaquin County Cooperative Extension Agent. 209-468-2085 |
| Fraction of Water Capacity when Irrigation is Applied (PCDEPL) | 0.55 | Marcia Campbell-Matthews San Joaquin County Cooperative Extension Agent. 209-468-2085 |
| Maximum Rate at which Irrigation is Applied (RATEAP) | 0.4 cm hr-1 | Marcia Campbell-Matthews San Joaquin County Cooperative Extension Agent. 209-468-2085 |
* EI = 100 ft-tons * in/ acre*hr
| Parameter | Value | Source |
|---|---|---|
| Initial Crop (INICRP) | 1 | Set to one for all crops (EPA. 2001) |
| Initial Surface Condition (ISCOND) | 1 | Marcia Campbell-Matthews San Joaquin County Cooperative Extension Agent. 209-468-2085 |
| Number of Different Crops (NDC) | 1 | Set to crops in simulation - generally one |
| Number of Cropping Periods (NCPDS) | 36 | Set to weather data. Meteorological File - Bakersfield, CA (W23155) or Sacramento, CA (W23232) |
| Maximum rainfall interception storage of crop (CINTCP) | 0.25 | Maximum recommended value for grass (EPA, 2001) |
| Maximum Active Root Depth (AMXDR) | 60 cm | Marcia Campbell-Matthews San Joaquin County Cooperative Extension Agent. 209-468-2085 |
| Maximum Canopy Coverage (COVMAX) | 100 | Marcia Campbell-Matthews San Joaquin County Cooperative Extension Agent. 209-468-2085 |
| Soil Surface Condition After Harvest (ICNAH) | 1 | Marcia Campbell-Matthews San Joaquin County Cooperative Extension Agent. 209-468-2085 |
| Date of Crop Emergence (EMD, EMM, IYREM) |
10/01 | Value set to approximate planting cycle. Alfalfa is planted one every five years with multiple cuttings in every year |
| Date of Crop Maturity (MAD, MAM, IYRMAT) |
28/12 | Value set to approximate planting cycle. Alfalfa is planted one every five years with multiple cuttings in every year |
| Date of Crop Harvest (HAD, HAM, IYRHAR) |
31/12 | Value set to approximate planting cycle. Alfalfa is planted one every five years with multiple cuttings in every year |
| Maximum Dry Weight (WFMAX) | 0.0 | Set to "0" Not used in simulation |
| SCS Curve Number (CN) | 90, 88, 89 | Gleams Manual Table A.3, Pasture/Range, Non-CNT, Poor (USDA, 1990) |
| Manning's N Value (MNGN) | 0.023 | RUSLE Project, A01OCOCM; Orchard, cover alley, Mulch till, Olympia, WA (USDA, 2000) |
| USLE C Factor (USLEC) | 0.046 - 0.221 | RUSLE Project; A01OCOCM; Orchard, cover alley, Mulch till, Olympia, WA. Variable with date (USDA, 2000) |
| Parameter | Value | Verification Source |
|---|---|---|
| Total Soil Depth (CORED) | 176 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) |
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NRCS, National Soils Characterization Database (NRCS, 2001) http://soils.usda.gov/survey/nscd/  |
| Bulk Density (BD) |
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| Initial Water Content (THETO) |
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| Compartment Thickness (DPN) |
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| Field Capacity (THEFC) |
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| Wilting Point (THEWP) |
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| Organic Carbon Content (OC) |
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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. 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).