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FLORIDA CITRUS
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The field used to represent citrus production in Florida is located in Collier or Hendry Counties in Southwest Florida, although citrus production areas cover a substantial portion of the state. Citrus production has been moving southward in an attempt to avoid frost damage that has occurred in recent years. According to the 1997 Census of Agriculture, Florida is the major producer of citrus (oranges) for the juice market and among the highest for the fresh market. Florida is also among the highest producers in other citrus (grapefruit, tangerines, tangelos, and mandarins). Citrus is generally grown in double rows of trees (beds) with swales between to move water off site. Areas under and between rows of trees are generally non-cultivated/non-maintained except for the occasional mowing. Row spacing (pairs or rows) is approximately 20 to 25 feet (paired beds may be less than 20 feet) and between tree spacing is approximately 12 to 15 feet. Row canopies tend to be 100 percent, while the canopy between rows is less to permit the operation of maintenance and harvest equipment. Irrigation is mostly by low-volume drip or micro-sprinkler systems. The soil selected to simulate the field is a Wabasso fine sand. Wabasso fine sand, is a sandy, siliceous, hyperthermic Alfic Alaquods. These soils are often used for citrus production and truck crops. Wabasso fine sand is a deep to very deep, poorly to very poorly drained, slow to ponded runoff, rapidly permeable in the top horizon and slow to very slowly permeable in the lower horizons soil that formed in sandy and loamy marine sediments. These soils are generally found on flatwoods, flood plains, and depressions and have slopes of 0 to 2 percent. The soil is extensive in Florida. Wabasso fine sand is a Hydrologic Group D soil.
| Parameter | Value | Source |
|---|---|---|
| Starting Date | January 1, 1948 | Meteorological File - Miami, Fl (W12839) |
| Ending Date | December 31, 1983 | Meteorological File - Miami, Fl (W12839) |
| Pan Evaporation Factor (PFAC) | 0.78 | PRZM Manual Figure 5.1 (EPA, 1998) |
| Snowmelt Factor (SFAC) | 0.0 cm C- 1 | Does not snow in Southern Florida such that accumulation is expected |
| Minimum Depth of Evaporation (ANETD) | 33.0 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) |
0.1 tons EI-1* | GLEAMS Manual, table of Representative Soils (USDA, 1990) |
| USLE LS Factor (USLELS) | 0.093 | GLEAMS Manual, table of Representative Soils (USDA, 1990) |
| USLE P Factor (USLEP) | 1.0 | Assume no practice under trees. |
| Field Area (AFIELD) | 172 ha | Area of Shipman Reservoir watershed (EPA, 1999) |
| NRCS Hyetograph (IREG) | 4 | PRZM Manual Figure 5.12 (EPA, 1998) |
| Slope (SLP) | 1% | Mid-point of soil series range (EPA, 2001) |
| Hydraulic Length (HL) | 600 m | Shipman Reservoir (EPA, 1999) |
* 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 | Set to represent fallow field |
| 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 - Miami, Fl (W12839) |
| Maximum rainfall interception storage of crop (CINTCP) | 0.25 | Maximum recommended value for orchards (EPA, 2001) |
| Maximum Active Root Depth (AMXDR) | 100 cm | Set to maximum of soil profile. Trees may root from 7-18 feet
http://edis.ifas.ufl.edu
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| Maximum Canopy Coverage (COVMAX) | 60 | http://edis.ifas.ufl.edu
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| Soil Surface Condition After Harvest (ICNAH) | 3 | Default, material under trees and between rows is generally left alone |
| Date of Crop Emergence (EMD, EMM, IYREM) |
15/02 | Date represent early to mid-season flower bloom for various varieties of citrus
http://edis.ifas.ufl.edu
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| Date of Crop Maturity (MAD, MAM, IYRMAT) |
15/10 | Date represent late season maturation for various varieties of citrus
http://edis.ifas.ufl.edu
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| Date of Crop Harvest (HAD, HAM, IYRHAR) |
15/12 | Date represents late season harvest
http://edis.ifas.ufl.edu
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| Maximum Dry Weight (WFMAX) | 0.0 | Set to "0" Not used in simulation |
| SCS Curve Number (CN) | 87, 85, 86 | Gleams Manual Table A.3, Meadows, no fallow conditions (USDA, 1990) |
| Manning's N Value (MNGN) | 0.014 | RUSLE Project; UC0CBCBC; Citrus bare ground; conventional tillage; Tampa, FL (USDA, 2000) |
| USLE C Factor (USLEC) | 0.324 - 0.488 | RUSLE Project; Variable with date, UC0CBCBC; Citrus bare ground; conventional tillage; Tampa, FL (USDA, 2000) |
| Parameter | Value | Verification Source |
|---|---|---|
| Total Soil Depth (CORED) | 100 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) |
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NRCS, National Soils Characterization Database (NRCS, 2001)http://soils.usda.gov/survey/nscd/
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| 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).