**Missouri Melons**

The Missouri melons scenario was developed to represent an environment
in which melons are grown in an area where rainfall is high and soils
are more vulnerable to runoff than most places where melons are grown in
the state. This scenario is intended to represent Missouri melon crops,
such as cantaloupes, honeydew, and watermelons. Based on the 2002 USDA
National Agricultural Statistics Summary, cantaloupe production accounts
for approximately 70% of the crop acreage (USDA, 2005). In 2002, 294,045
acres of melons were grown nationally. Missouri ranks 11^th^ in the
nation in production of melons with 5,360 acres or 1.8% of the national
acreage.

Melons belong to the cucurbit family of plants, known as Cucurbitaceae,
which includes cucumbers, gourds, squash, and pumpkins. There are
several different genus names used in the family. Cantaloupes (*Cucumis
melo* L. var. *antalupensis*) and honeydews (*Cucumis melo* L. var.
*inodorus*) are classified in the same genus. Mixed melons, including
crenshaw, casaba, Santa Claus, Persian, Juan Canary, piel de sapo, and
other melon types are in this genus, while watermelons are in a
different genus *Citrullus lanatus* (Thunb.) Matsum & Nakai.

In 2002, Missouri melon production was limited to cantaloupes and
watermelons, and these crops are predominantly grown in the 'boot heel'
region in the southeast corner of the state around New Madrid; (there
were no reported honeydew melons in Missouri in 2002). Seventy percent
of the acreage was grown in just three counties in this part of the
state: Dunklin, Mississippi, and Butler. Most of the melons produced
were watermelons (3,505 acres) with only a small cantaloupe production
(202 acres). Dunklin County, which has the most cantaloupe as well as
watermelon acres in the state, was selected as the location for the MO
melon scenario. This county, which is in the southern Mississippi River
Basin, is drained by the St. Francis River and its tributaries. The site
for this scenario is in MLRA O131a, the Southern Mississippi River
Alluvium. This area is an alluvial plain along the Mississippi River,
south of its confluence with the Ohio River. Cotton, corn, soybeans,
sorghum are the dominant crops.

While Saint Louis is closer than Memphis to this site (120 mi versus 174
for Memphis, TN), Memphis was selected for the weather station as it has
more rainfall than Saint Louis and is likely to result in a more
conservative scenario for Dunklin County. Kennett, the largest town in
Dunklin County, receives 49.6 in of rainfall on average.

  ------------- ------------------- -------------------- ------------------
  **Table 1.**                                           
  Candidate                                              
  weather                                                
  stations in                                            
  Missouri for                                           
  the MO melon                                           
  scenario.                                              

  Station ID    Location            Annual Average       June Average
                                    Precipitation        Precipitation

  03945         Columbia, MO        40.28 in             4.02 in

  03947         Kansas City, MO     35.5 in              4.73 in

  13994         Saint Louis, MO     38.8 in              3.7 in

  13995         Springfield, MO     45.0 in              5.0 in

  **13893\***   **Memphis, TN**     **54.6 in**          **4.3 in**
  ------------- ------------------- -------------------- ------------------

\* The weather station selected for the scenario is Memphis, TN.

Soils in this area have dominantly formed in alluvium (USDA, 2006). The
soil selected for the scenario is the Dubbs loamy sand which is
classified as a fine-silty, mixed, active, thermic Typic Hapludalfs. The
Dubbs soil is not a benchmark soil but is extensive in Dunklin County,
covering 11.2% of the land area. The Dubbs soil is in Hydrologic Group
B. Although C soils are extensive in Dunklin County, melons are not
tolerant of poorly drained soils, so an extensive Group B soil was
chosen to represent a vulnerable soil that is used for melon agriculture
in this county. There are two soil series that list vegetable crops on
the soil series description in Dunklin County, the Canalou and Eustis
soils. The Canalou[^1] soil is in Hydrologic Group A and is less prone
to runoff than Group B soils where melons may be grown. The Eustis soil
is only found on slopes over 15% in Dunklin County, which is unsuitable
for melon culture[^2]. The Dubbs soil covers 12.9% of the land area in
the county. Slopes range from 0 to 1% in this part of the county.

+-----------------+----------+-----------------------------------------+
| **Table 2.**    |          |                                         |
| PRZM 3.12.2     |          |                                         |
| Climate and     |          |                                         |
| Time Parameters |          |                                         |
| for Dunklin     |          |                                         |
| County, MO      |          |                                         |
| Melon           |          |                                         |
| Scenario**.**   |          |                                         |
+-----------------+----------+-----------------------------------------+
| Parameter       | Value    | Source/Comments                         |
+-----------------+----------+-----------------------------------------+
| Starting Date   | Jan. 1,  | Meteorological File from Memphis, TN    |
|                 | 1961     | (13893)                                 |
+-----------------+----------+-----------------------------------------+
| Ending Date     | Dec. 31, | Meteorological File from Memphis, TN    |
|                 | 1990     | (13893)                                 |
+-----------------+----------+-----------------------------------------+
| Pan Evaporation | 0.76     | PRZM Manual Figure 5.1. (USEPA, 2006).  |
| Factor (PFAC)   |          |                                         |
+-----------------+----------+-----------------------------------------+
| Snowmelt Factor | 0.36 cm  | Maximum value of minimum range of PRZM  |
| (SFAC)          | °C^-1^   | Manual Table 5.1 (USEPA, 2006)          |
+-----------------+----------+-----------------------------------------+
| Minimum Depth   | 17.5 cm  | PRZM Manual (USEPA, 2006) Average of    |
| of              |          | 15-20 cm                                |
|                 |          |                                         |
| Evaporation     |          |                                         |
| (ANETD)         |          |                                         |
+-----------------+----------+-----------------------------------------+
| Pan Factor Flag | 0        | Pan Factor Flag set to read from        |
| (IPEIND)        |          | weather data as per guidance (USEPA,    |
|                 |          | 2004)                                   |
+-----------------+----------+-----------------------------------------+

USLE C factor and Manning's N values are from a RUSLE assessment for
soybeans using weather from Carbondale,IL. (RUSLE Project File MA5SBWWM.
This set of values was chosen as it was in the same region of the
country and the dataset generated for soybeans were the most similar
available for this area of the country.

+-----------------+----------+-----------------------------------------+
| **Table 3.**    |          |                                         |
| PRZM 3.12.2     |          |                                         |
| Erosion and     |          |                                         |
| Landscape       |          |                                         |
| Parameters for  |          |                                         |
| Dunklin County, |          |                                         |
| MO Melon.       |          |                                         |
+=================+==========+=========================================+
| Parameter       | Value    | Source/Comments                         |
+-----------------+----------+-----------------------------------------+
| Method to       | 4 (MUSS) | PRZM Manual (USEPA, 2006)               |
| Calculate       |          |                                         |
| Erosion         |          |                                         |
| (ERFLAG)        |          |                                         |
+-----------------+----------+-----------------------------------------+
| USLE K Factor   | 0.49     | USDA NRCS Soil Data Mart                |
| (USLEK)         | tons     | (http://soildatamart.nrcs.usda.gov/)    |
|                 | EI^-1\*^ |                                         |
+-----------------+----------+-----------------------------------------+
| USLE LS Factor  | 0.15     | Value listed for 0.5% slope at 400 feet |
| (USLELS)        |          | using equation in Hann and Barfield     |
|                 |          | (1978)                                  |
+-----------------+----------+-----------------------------------------+
| USLE P Factor   | 1        | No contouring PRZM Manual Table 5.6     |
| (USLEP)         |          | (USEPA, 2006)                           |
+-----------------+----------+-----------------------------------------+
| Field Area      | 172 ha   | Area of Shipman Reservoir watershed     |
| (AFIELD)        |          | (USEPA, 1999)                           |
+-----------------+----------+-----------------------------------------+
| NRCS Hyetograph | 3        | PRZM Manual Figure 5.8 (USEPA, 2006)    |
| (IREG)          |          |                                         |
|                 |          | Type II, IREG=3                         |
+-----------------+----------+-----------------------------------------+
| Slope (SLP)     | 0.5%     | Mean value for Dubbs loamy sand         |
+-----------------+----------+-----------------------------------------+
| Hydraulic       | 600 m    | Shipman Reservoir (USEPA, 1999)         |
| Length (HL)     |          |                                         |
+-----------------+----------+-----------------------------------------+
| Irrigation Flag | 0        | No irrigation                           |
| (IRFLAG)        |          |                                         |
+-----------------+----------+-----------------------------------------+
| \* EI = 100     |          |                                         |
| ft-tons \* in/  |          |                                         |
| acre\*hr        |          |                                         |
+-----------------+----------+-----------------------------------------+
|                 |          |                                         |
+-----------------+----------+-----------------------------------------+

+-----------------+----------+-----------------------------------------+
| **Table 4.**    |          |                                         |
| PRZM 3.12.2     |          |                                         |
| Crop Parameters |          |                                         |
| for Dunklin     |          |                                         |
| County, MO      |          |                                         |
| Melon.          |          |                                         |
+=================+==========+=========================================+
| Parameter       | Value    | Source/Comments                         |
+-----------------+----------+-----------------------------------------+
| Initial Crop    | 1        | Set to one for all crops (EPA, 2004).   |
| (INICRP)        |          |                                         |
+-----------------+----------+-----------------------------------------+
| Initial Surface | 1        | 1= fallow, default -- parameter is      |
| Condition       |          | ignored as ERFLAG \> 0.                 |
|                 |          |                                         |
| (ISCOND)        |          |                                         |
+-----------------+----------+-----------------------------------------+
| Number of       | 1        | Set to number of crops in simulation.   |
| Different Crops |          |                                         |
| (NDC)           |          |                                         |
+-----------------+----------+-----------------------------------------+
| Number of       | 30       | Set to weather data in meteorological   |
| Cropping        |          | file: Memphis. TN (W13893).             |
| Periods (NCPDS) |          |                                         |
+-----------------+----------+-----------------------------------------+
| Maximum         | 0.25 cm  | Moderate to heavy canopy PRZM table     |
| Rainfall        |          | 5-4. Value consistent with TX melons    |
| Interception    |          | (USEPA, 2004).                          |
| Storage of Crop |          |                                         |
| (CINTCP)        |          |                                         |
+-----------------+----------+-----------------------------------------+
| Maximum Active  | 46 cm    | Kemble JK. Basics of crop irrigation.   |
| Root Depth      |          | Alabama cooperative extension system.   |
| (AMXDR)         |          | ANR-1169 April 2000                     |
+-----------------+----------+-----------------------------------------+
| Maximum Canopy  | 100%     | Value consistent with TX melons (EPA,   |
| Coverage        |          | 2004).                                  |
| (COVMAX)        |          |                                         |
+-----------------+----------+-----------------------------------------+
| Soil Surface    | 3        | 3 = residue. Melons are picked and      |
| Condition After |          | packed directly from the vines in the   |
| Harvest (ICNAH) |          | field (USDA, 1999).                     |
+-----------------+----------+-----------------------------------------+
| Date of Crop    | 10/04/61 | Earliest planting of watermelon in MO.  |
| Emergence       |          | Seedling planted so emergence           |
|                 |          | corresponds with planting Associated    |
| (EMD, EMM,      |          | with first RUSLE Date 10 days after     |
| IYREM)          |          | planting.                               |
+-----------------+----------+-----------------------------------------+
| Date of Crop    | 01/07/61 | Watermelons are usually about 85 days   |
| Maturity        |          | to first harvest which is being used as |
|                 |          | the maturity date (USDA Crop Profile,   |
| (MAD, MAM,      |          | 2000)                                   |
| IYRMAT)         |          |                                         |
+-----------------+----------+-----------------------------------------+
| Date of Crop    | 31/07/61 | USDA Crop Profile for Melons in MO      |
| Harvest (HAD,   |          | (2000)                                  |
| HAM, IYRHAR)    |          |                                         |
+-----------------+----------+-----------------------------------------+
| Maximum Dry     | 0.0      | Not used in scenario                    |
| Weight (WFMAX)  |          |                                         |
+-----------------+----------+-----------------------------------------+
| Maximum Crop    | 25 cm    | Value consistent with TX melons (EPA,   |
| Height (HTMAX)  |          | 2004).                                  |
+-----------------+----------+-----------------------------------------+
| SCS Curve       | 86, 81,  | PRZM Table 5.10, B Soil, fallow, and    |
| Number (CN)     | 86       | row crop, contoured, poor condition     |
+-----------------+----------+-----------------------------------------+
| Manning's N     | 0.023    | RUSLE Project; MA5SBWWM; soybeans,      |
| Value (MNGN)    |          | Carbondale,IL weather station; mulch    |
|                 |          | tillage(USDA, 2000)., dates adjusted to |
|                 |          | match planting and harvest              |
+-----------------+----------+-----------------------------------------+
| USLE C Factor   | 0.0      | RUSLE Project; MA5SBWWM; soybeans,      |
| (USLEC)         | 42-0.312 | Carbondale, IL weather station; mulch   |
|                 |          | tillage(USDA, 2000). dates adjusted to  |
|                 |          | match planting and harvest              |
+-----------------+----------+-----------------------------------------+

+----------------------+-------------------+--------------------------+
| **Table 5.** PRZM    |                   |                          |
| 3.12.2 Dubbs Loamy   |                   |                          |
| Sand Soil Parameters |                   |                          |
| Dunklin County, MO   |                   |                          |
| Melon.               |                   |                          |
+----------------------+-------------------+--------------------------+
| Parameter            | Value             | Source/Comments          |
+----------------------+-------------------+--------------------------+
| Total Soil Depth     | 158 cm            | NRCS Soil Data Mart      |
| (CORED)              |                   | (SDM)                    |
|                      |                   | (http://soi              |
|                      |                   | ldatamart.nrcs.usda.gov) |
+----------------------+-------------------+--------------------------+
| Number of Horizons   | 3                 | NRCS Soil Data Mart      |
| (NHORIZ)             |                   | (SDM)                    |
+----------------------+-------------------+--------------------------+
| Horizon Thickness    | 10 cm (HORIZN =   | NRCS Soil Data Mart      |
| (THKNS)              | 1)                | (SDM). The top horizon   |
|                      |                   | was split into two       |
|                      | 24 cm (HORIZN =   | horizons as per PRZM     |
|                      | 2)                | Scenario Guidance (EPA,  |
|                      |                   | 2004).                   |
|                      | 124 cm (HORIZN =  |                          |
|                      | 3)                |                          |
+----------------------+-------------------+--------------------------+
| Bulk Density (BD)    | 1.42 g/cm^3^      | NRCS Soil Data Mart      |
|                      | (HORIZN = 1)      | (SDM)                    |
|                      |                   | ([                       |
|                      | 1.42 g/cm^3^      | http://soildatamart.nrcs |
|                      | (HORIZN = 2)      | .usda.gov](http://soilda |
|                      |                   | tamart.nrcs.usda.gov/)). |
|                      | 1.58 g/cm^3^      | Midpoint of the reported |
|                      | (HORIZN = 3)      | range. PRZM Scenario     |
|                      |                   | Guidance (EPA, 2004).    |
+----------------------+-------------------+--------------------------+
| Initial Water        | 0.264 cm^3^/cm^3^ | NRCS Soil Data Mart      |
| Content (THETO)      | (HORIZN =1)       | (SDM); values are mean   |
|                      |                   | available water plus the |
|                      | 0.264 cm^3^/cm^3^ | wilting point water      |
|                      | (HORIZN =2)       | content of Dubbs loamy   |
|                      |                   | sand soils.              |
|                      | 0.218 cm^3^/cm^3^ |                          |
|                      | (HORIZN = 3)      |                          |
+----------------------+-------------------+--------------------------+
| Compartment          | 0.1 cm (HORIZN =  | NRCS Soil Data Mart      |
| Thickness (DPN)      | 1)                | (SDM)                    |
|                      |                   | ([                       |
|                      | 2 cm (HORIZN = 2) | http://soildatamart.nrcs |
|                      |                   | .usda.gov](http://soilda |
|                      | 2 cm (HORIZN = 3) | tamart.nrcs.usda.gov/)). |
|                      |                   | PRZM Scenario Guidance   |
|                      |                   | (EPA, 2004).             |
+----------------------+-------------------+--------------------------+
| Field Capacity       | 0.264 cm^3^/cm^3^ | NRCS Soil Data Mart      |
| (THEFC)              | (HORIZN =1)       | (SDM); values are mean   |
|                      |                   | available water plus the |
|                      | 0.264 cm^3^/cm^3^ | wilting point water      |
|                      | (HORIZN =2)       | content of Dubbs loamy   |
|                      |                   | sand soils.              |
|                      | 0.218 cm^3^/cm^3^ |                          |
|                      | (HORIZN = 3)      |                          |
+----------------------+-------------------+--------------------------+
| Wilting Point        | 0.034 cm^3^/cm^3^ | NRCS Soil Data Mart      |
| (THEWP)              | (HORIZN =1)       | (SDM) Soil               |
|                      |                   | Characterization data;   |
|                      | 0.034 cm^3^/cm^3^ | values are mean 15-bar   |
|                      | (HORIZN =2)       | water contents of Dubbs  |
|                      |                   | loamy sand soils.        |
|                      | 0.053 cm^3^/cm^3^ |                          |
|                      | (HORIZN = 3)      |                          |
+----------------------+-------------------+--------------------------+
| Organic Carbon       | 0.725% (HORIZN =  | NRCS SDM; values for     |
| Content (OC)         | 1)                | horizons 1 to 3 = mean   |
|                      |                   | %OM / 1.724. PRZM        |
|                      | 0.725% (HORIZN =  | Scenario Guidance        |
|                      | 2)                | (USEPA, 2004).           |
|                      |                   |                          |
|                      | 0.174% (HORIZN =  |                          |
|                      | 3)                |                          |
+----------------------+-------------------+--------------------------+

**References**

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 KY 40506. pp
286.

USDA. 1999. Crop Profile for Melons in Missouri. U.S. Department of
Agriculture, Pest Management Centers. October 1999. Online at:
<http://www.ipmcenters.org/CropProfiles/docs/mowatermelons.pdf>

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).

USDA. 2005. 2002 Census of Agriculture. U.S. Department of Agriculture,
National Agricultural Statistics Service (NASS). Online at:
<http://www.nass.usda.gov/index.asp>.

USDA. 2003. Official Series Description -- Dubbs Series. U.S. Department
of Agriculture, Natural Resources Conservation Service (NRCS). Dec.
2006. Online at: <http://www2.ftw.nrcs.usda.gov/osd/dat/D/DUBBS.html>

USEPA. 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, DC.

USEPA. 2004. 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, DC.

USEPA. 2006. 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 3.12.2.* National Exposure Research Laboratory, Office of
Research and Development, U.S. Environmental Protection Agency, Athens,
GA.

[^1]: <http://www2.ftw.nrcs.usda.gov/osd/dat/C/CANALOU.html>

[^2]: <http://www2.ftw.nrcs.usda.gov/osd/dat/E/EUSTIS.html>