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CALIFORNIA FRUITS: NON-CITRUS (Northern and Southern)

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The field used to represent non-citrus fruit production in California is located in Fresno County in the Central Valley, although non-citrus fruit production covers most of the central portion of the state, but mainly on Eastern slopes. According to the 1997 Census of Agriculture, California is the major producer of peaches, plums/prunes, and kiwi for the fresh market, and among the highest producers in other non-citrus fruit such as pears and apples. Areas under and between rows of trees may or may not be maintained depending on the location. Row spacing varies depending on the fruit tree (from approximately 15 to 25 feet) as does the tree spacing (approximately 12 to 20 or more feet). Row canopies tend to be very close to 100 percent, while the canopy between rows is much less to permit the operation of maintenance and harvest equipment. Irrigation is by furrow and flood for most crops, but low-volume drip or micro-sprinkler systems are growing in popularity. The soil selected to simulate the field is a benchmark soil, Exeter loam. Exeter loam, is a fine-loamy, mixed, superactive, thermic Typic Durixeralfs. These soils are often used for citrus production under irrigation. Exeter loam is a moderately deep, moderately well drained, very slow to medium runoff soil that formed in alluvium mainly from granite sources. The soil also consists of a duripan. The Exeter loam has moderately slow permeability above the duripan and very slow permeability within the duripan. These soil are generally found on alluvial fans and stream terraces at elevations of up to 700 feet above mean sea level and have slopes of 0 to 9 percent. The soil is extensive in MLRA 17. Exeter loam is a Hydrologic Group C soil.

Table 1
PRZM 3.12 Climate and Time Parameters for Fresno County, California - Fruit (non-Citrus)
ParameterValueSource
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 Kurt Hembree (559.456.7556)
UC Cooperative Extension Office, Fresno County
Snowmelt Factor (SFAC) 0.0 cm C- 1 Kurt Hembree (559.456.7556)
UC Cooperative Extension Office, Fresno County
Minimum Depth of Evaporation (ANETD) 17.0 cmPRZM Manual Figure 5.2 (EPA, 1998)

Table 2
PRZM 3.12 Erosion and Landscape Parameters for Fresno County, California - Fruit (non-Citrus)
ParameterValueSource
Method to Calculate Erosion (ERFLAG) 4 (MUSS)PRZM Manual (EPA, 1998)
USLE K Factor (USLEK) 0.34 tons EI-1* NRI - Average value listed for the soil series Exeter
USLE LS Factor (USLELS) 0.018NRI - Average value listed for the soil series Exeter
USLE P Factor (USLEP) 1.0NRI - Average value listed for the soil series Exeter
Field Area (AFIELD) 172 haArea of Shipman Reservoir watershed (EPA, 1999)
NRCS Hyetograph (IREG) 2 PRZM Manual Figure 5.12 (EPA, 1998); based on crops grown on Eastern side of slopes.
Slope (SLP) 9% Kurt Hembree (559.456.7556)
UC Cooperative Extension Office, Fresno County
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 Fresno County, California - Fruit (non-Citrus)
ParameterValueSource
Initial Crop (INICRP) 1Set to one for all crops (EPA, 2001)
Initial Surface Condition (ISCOND) 1Mark Freeman, Fresno County Cooperative Extension Agent.
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) 0.25Maximum recommended value for grass (EPA, 2001)
Maximum Active Root Depth (AMXDR) 30 cmMark Freeman, Fresno County Cooperative Extension Agent.
Maximum Canopy Coverage (COVMAX) 90 Mark Freeman, Fresno County Cooperative Extension Agent.
Soil Surface Condition After Harvest (ICNAH) 3Mark Freeman, Fresno County Cooperative Extension Agent.
Date of Crop Emergence
(EMD, EMM, IYREM)
21/01 Value set to a dates for plums based on Health Effects Division information
Date of Crop Maturity
(MAD, MAM, IYRMAT)
21/06 Value set to a dates for plums based on Health Effects Division information
Date of Crop Harvest
(HAD, HAM, IYRHAR)
01/08 Value set to a dates for plums based on Health Effects Division information
Maximum Dry Weight (WFMAX) 0.0Set to "0" Not used in simulation
SCS Curve Number (CN) 84, 79, 82 Gleams Manual Table A.3, Meadows, no fallow conditions (USDA, 1990)
Manning's N Value (MNGN) 0.023 RUSLE Project; C21OCOCM for orchards, covered alley in Sacramento (USDA, 2000)
USLE C Factor (USLEC) 0.034 - 0.221 RUSLE Project; Variable with date, C21OCOCM for orchards, covered alley in Sacramento (USDA, 2000)

Table 4
PRZM 3.12 Exeter Soil Parameters for Fresno County, California - Fruit (non-Citrus )
ParameterValue Verification Source
Total Soil Depth (CORED) 183 cm NRCS, National Soils Characterization Database (NRCS, 2001)
Number of Horizons (NHORIZ) 2 (Base horizons)
First and Second Soil Horizons (HORIZN = 1,2)
Horizon Thickness (THKNS)
  • 10 cm (HORIZN = 1)
  • 173 cm (HORIZN = 2)
NRCS, National Soils Characterization Database (NRCS, 2001) http://soils.usda.gov/survey/nscd/ Exit EPA Disclaimer
Bulk Density (BD)
  • 1.59 g cm-3 (HORIZN = 1)
  • 1.76 g cm-3 (HORIZN = 2)
Initial Water Content (THETO)
  • 0.16 cm3-H2O cm3-soil (HORIZN =1)
  • 0.2 cm3-H2O cm3-soil (HORIZN =2)
Compartment Thickness (DPN)
  • 0.1 cm (HORIZN = 1)
  • 17.3 cm (HORIZN = 2)
Field Capacity (THEFC)
  • 0.16 cm3-H2O cm3-soil (HORIZN = 1)
  • 0.2 cm3-H2O cm3-soil (HORIZN = 2)
Wilting Point (THEWP)
  • 0.06 cm3-H2O cm3-soil (HORIZN = 1)
  • 0.11 cm3-H2O cm3-soil (HORIZN = 2)
Organic Carbon Content (OC)
  • 0.46% (HORIZN = 1)
  • 0.19% (HORIZN = 2)

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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