POTENTIAL HEAT UNIT (PHU) PROGRAM
(These directions are also included in the PHU_program.pdf file enclosed in 
the download)

	The potential heat unit program will calculate the total number of
heat units required to bring a plant to maturity using 1) long-term maximum 
and minimum temperature data, 2) the base or minimum temperature required by 
the plant for growth, 3) and the average number of days for the plant to 
reach maturity. A description of plant heat units follows the directions for
installation and program use.

To install:
This program is designed to be installed from a diskette, so a few extra 
steps are required.
1) Download phuinstall.zip.
2) Extract installation files contained in phuinstall.zip and copy to 
   diskette.
3) Open MSDOS command prompt window, change to diskette drive and type 
   "install.exe"
4) The installation program will offer the option of installing 2 different
   software packages. You will want to choose the first package (EPIC PHU
   program). The next prompt screen will ask you to specify the diskette 
   drive and the installation drive and directory. Use the arrow keys to 
   move from field to field and press the ENTER key to start the 
   installation process.

To run:
This program runs in the MSDOS mode. You will need to open a MSDOS command 
prompt window and move to the directory where the PHU program is installed 
to operate the UTIL interface and execute the program.

Build weather input file:
1) At the command prompt, type "util phuplt" and press the ENTER key.
2) The UTIL editor will open and will display the data fields. Three types 
   of information are required: the latitude of the watershed and average 
   monthly maximum and minimum temperatures. For watersheds in the United 
   States, an autoload feature is included that will extract the required 
   data from the default U.S. weather generator database. 

To use the autoload:
a) Type "locweat 41 72" (where 41 is replaced by the latitude and 72 is 
   replaced by the longitude of your location) and press the ENTER key.
b) A list of weather stations in the database is displayed. The weather 
   station closest to the specified latitude and longitude is listed first. 
   Use the arrow keys to move up and down the list. Select a weather station
   by pressing the ENTER key when the desired weather station is highlighted.
c) The weather data is loaded into the editor.
If custom weather generator files are being used in a simulation, the user 
should do the following:
a) Enter the mean monthly maximum and minimum temperature from the custom 
   weather generator file and the latitude of the watershed.
b) Type any comments about the data on the first line of the file.
3) Save the file by pressing the F4 key and entering a file name 
   (e.g. co1.wth).
4) Exit the UTIL editor by pressing the F3 key.

Provide plant growth information:
1) To view the plant growth file, type "util phucrp"
2) A list of plants is displayed. For each plant, the following information 
   is provided: the season in which the plant grows (summer or winter, i.e.
   warm season or cool season), the optimal and minimum temperature for 
   plant growth, the amount of dry-down the plant undergoes prior to 
   harvesting, and the number of days required for the plant to reach 
   maturity or the number of days between planting and harvest.
3) Make sure that the plant of interest is listed. If it is not listed, add
   the plant to the file. The season in which the plant grows, and the 
   optimal and minimum temperature for plant growth can be obtained from 
   the plant growth database (crop.dat). The amount of dry-down and the 
   number of days required for the plant to reach maturity are a function 
   of the plant variety. The length of the growing season may be listed for
   up to 5 different varieties of a plant species.
      Comment: Note that the number of days to maturity for pine is 7300. 
      For modeling purposes, the value for number of days to maturity for
      trees should be replaced with the growing season for the plant, i.e.
      the number of days between budding and leaf senescence.
4) If changes were made to the file, save the file by pressing the F4 key.
5) Exit the UTIL editor by pressing the F3 key.

Obtain results:
1) At the MSDOS command prompt, type "phu"
2) The program will ask for the name of the weather data file. Type the name 
   of the file and press the ENTER key.
3) The program will write the name of the output file to the screen. Once 
   the program terminates, open the output file with an editor.
4) For each plant listed in the phucrp.dat file, the following information 
   will be given:
   CROP    CROP   VARIETY
    NO.    NAME     NO.         #1        #2        #3        #4        #5
    1   soybeans     1      120.00    115.00    110.00    105.00    100.00
                             1551.     1476.     1401.     1326.     1251.
                               .02       .02       .02       .02       .02
                                 8         8         8         8         8

The first line lists the days to maturity for the variety. The second line 
lists the total heat units required to bring the plant to maturity in the 
watershed. The third line provides the time of planting by heat unit 
scheduling and the fourth line provides the time of planting by Julian date.