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CALIFORNIA ALMOND/WALNUTS (Northern and Southern)

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The field used to represent almond production in California is located in San Joaquin County in the Central Valley, although almonds production areas are well distributed throughout the Central and Sacramento Valleys. According to the 1997 Census of Agriculture, California is the major producer of almonds and walnuts in the U.S.. Almonds are generally grown on low terraces. All types of irrigation is used. The floor of almond groves are kept smooth and clear to facilitate collection of the nuts after harvesting which is accomplished by shaking the trees. The soil selected to simulate the field is a Manteca fine sandy loam. Manteca fine sandy loam is a coarse-loamy, mixed, thermic Haplic Durixerolls. These soils are often used for a variety of crops including Almonds. Manteca fine sandy loam consists of moderately deep, moderately well drained, slow runoff, moderately permeable above the hardpan soil that formed in alluvium mainly from mixed rock sources. These soil are generally found on low terraces at elevations of 20 to 110 feet above mean sea level and have slopes of 0 to 2 percent. The soil is of small extent in MLRA17. Manteca fine sandy loam is a Hydrologic Group C soil.

Table 1
PRZM 3.12 Climate and Time Parameters for San Joaquin County, California - Almonds
ParameterValueSource
Starting Date January 1, 1948 Meteorological File -
Southern: Bakersfield, CA (W23155) or
Northern: Sacramento, CA (W23232)
Ending Date December 31, 1983 Meteorological File -
Southern: Bakersfield, CA (W23155)or
Northern: Sacramento, CA (W23232)
Pan Evaporation Factor (PFAC) 0.7PRZM Manual Figure 5.1 (EPA, 1998)
Snowmelt Factor (SFAC) 0.55 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 San Joaquin County, California - Almonds
ParameterValueSource
Method to Calculate Erosion (ERFLAG) 4 (MUSS)PRZM Manual (EPA, 1998)
USLE K Factor (USLEK) 0.28 tons EI-1* NRI - Average value listed for the soil series Manteca
USLE LS Factor (USLELS) 0.2NRI - Average value listed for the soil series Manteca
USLE P Factor (USLEP) 1.0NRI - Average value listed for the soil series Manteca
Field Area (AFIELD) 172 haArea of Shipman Reservoir watershed (EPA, 1999)
NRCS Hyetograph (IREG) 1PRZM Manual Figure 5.12 (EPA, 1998)
Slope (SLP) 2 %Paul Verdegaal
San Joaquin County Cooperative Extension 209-468-9494
Hydraulic Length (HL) 600 mShipman Reservoir (EPA, 1999)
Irrigation Flag (IRFLAG) 2 (cropping period only) Based on recommendations from farm advisors for general flooding for crop irrigation
Irrigation Type (IRTYP) 1 (Flood) Based on recommendations from farm advisors for general flooding for crop irrigation
Leaching Factor (FLEACH) 0.1Estimated
Fraction of Water Capacity when Irrigation is Applied (PCDEPL) 0.55 Based on recommendations from farm advisors for general flooding for crop irrigation
Maximum Rate at which Irrigation is Applied (RATEAP) 0.4 cm hr-1PRZM Manual, Table 5.33 (EPA, 1998)

* EI = 100 ft-tons * in/ acre*hr


Table 3
PRZM 3.12 Crop Parameters for San Joaquin County, California - Almonds
ParameterValueSource
Initial Crop (INICRP) 1Set to one for all crops (EPA, 2001)
Initial Surface Condition (ISCOND) 3 Paul Verdegaal
San Joaquin County Cooperative Extension 209-468-9494
Number of Different Crops (NDC) 1Set 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 PIC; confirmed using Table 5.4 from PRZM Manual (Burns, 1992 and EPA, 1985)
Maximum Active Root Depth (AMXDR) 120 Paul Verdegaal
San Joaquin County Cooperative Extension 209-468-9494
Maximum Canopy Coverage (COVMAX) 90 Paul Verdegaal
San Joaquin County Cooperative Extension 209-468-9494
Soil Surface Condition After Harvest (ICNAH) 2 Paul Verdegaal
San Joaquin County Cooperative Extension 209-468-9494
Date of Crop Emergence
(EMD, EMM, IYREM)
18/01Values complied by HED for Almonds
Date of Crop Maturity
(MAD, MAM, IYRMAT)
02/08Values complied by HED for Almonds
Date of Crop Harvest
(HAD, HAM, IYRHAR)
13/09Values complied by HED for Almonds
Maximum Dry Weight (WFMAX) 0.0Set to "0" Not used in simulation
SCS Curve Number (CN) 84, 79, 82Gleams Manual Table A.3, Meadow
Manning's N Value (MNGN) 0.023 RUSLE Project; C21OCOCM for orchards, cov alley in Sacramento (USDA, 2000)
USLE C Factor (USLEC) 0.34 - 0.221 RUSLE Project; C21OCOCM for orchards, cov alley in Sacramento (USDA, 2000)

Table 4
PRZM 3.12 Manteca Soil Parameters for San Joaquin County, California - Almonds
ParameterValue Verification Source
Total Soil Depth (CORED) 317 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)
  • 10 cm (HORIZN = 1)
  • 7 cm (HORIZN = 2)
  • 300 cm (HORIZN = 3)
NRCS, National Soils Characterization Database (NRCS, 2001) http://soils.usda.gov/survey/nscd/ Exit EPA Disclaimer Ed Russell (USDA-NRCS, Fresno)
Bulk Density (BD)
  • 1.55 g cm-3 (HORIZN = 1,2)
  • 1.6 g cm-3 (HORIZN = 3)
Initial Water Content (THETO)
  • 0.22 cm3-H2O cm3-soil (HORIZN =1,2)
  • 0.23 cm3-H2O cm3-soil (HORIZN =3)
Compartment Thickness (DPN)
  • 0.1 cm (HORIZN = 1)
  • 3.5 cm (HORIZN =2)
  • 30 cm (HORIZN = 3)
Field Capacity (THEFC)
  • 0.22 cm3-H2O cm3-soil (HORIZN = 1,2)
  • 0.23 cm3-H2O cm3-soil (HORIZN = 3)
Wilting Point (THEWP)
  • 0.1 cm3-H2O cm3-soil (HORIZN = 1,2)
  • 0.23 cm3-H2O cm3-soil (HORIZN = 3)
Organic Carbon Content (OC)
  • 0.81% (HORIZN = 1,2)
  • 0.18% (HORIZN = 3)

Burns. 1992. Burns, L.A., (Coordinator), B.W. Allen, Jr., M.C. Barber, S.L. Bird, J.M. Cheplick, M.J. Fendley, D.R. Hartel, C.A. Kittner, F.L. Mayer, Jr., L.A. Suarez, and S.E. Wooten. Pesticide and Industrial Chemical Risk Analysis and Hazard Assessment, Version 3.0. (PIRANHA) Environmental Research Laboratory, Office of Research and Development, U.S. Environmental Protection Agency, Athens, GA. 1992.

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).

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