Irrigation Scheduler Help Contents
Entering Field, Crop & Soil Data
Entering Weather & Irrigation Data
Viewing the Irrigation Schedule
Getting Temperature Data from Other Sources
Getting Started
The Irrigation Scheduler estimates irrigation water needs. Before you can use the program, you will need to collect the following information for each irrigated field:
- Location (you can select any of the 48 contiguous U.S. states or a non-specific "international" location).
- Latitude of irrigated field (easily determined - see below).
- Crop (this version supports corn for grain, corn for silage, soybean, dry bean, green bean, winter wheat, established alfalfa, sweet corn, potato, melon, tomato and other crops).
- Crop emergence date.
- Length of crop's growing season (number of days from emergence to maturity).
- Crop rooting depth (see below for typical values).
- Soil profile water holding capacity. If you know the field's predominant soil type, you can let the program retrieve your soil survey's data and calculate this for you.
- Minimum soil moisture at which irrigation should begin (see below for typical values).
After this initial information has been entered, you only need to record and enter the following daily information throughout the growing season:
- High and low temperature.
- Wind speed (optional).
- Relative humidity (optional).
- Rainfall amount.
- Irrigation amount.
With this information, the program can then estimate how much irrigation water is needed and how soon it should be applied.
For more information, see the following topics:
Entering Field, Crop & Soil Data
Entering Weather & Irrigation Data
Operating the Program
The Irrigation Scheduler program consists of the following parts:
- A panel where you enter field, crop, and soil information.
- Another panel where you enter temperature, wind speed, humidity, precipitation, and irrigation values.
- A row of buttons that you click when you want to create a new data file, open an existing data file, save your data, or exit the program.
- A preview window where you can view, print and export the irrigation schedule.
Each field's data is saved in a separate data file with an .irr extension. When the program starts, it creates a new file automatically (indicated by [New File] on the title bar). You can enter data into this new file, or you can open and edit a data file that you named and saved during a previous session.
Tip: If you're new to the program, you can try it out by opening one of the sample data files that were installed along with the program.
When editing a data file, you'll only see one data entry panel at a time. To switch between panels, click on the tabs labeled Field, Crop & Soil Data and Weather & Irrigation Data.
Tip: Anytime you need help with what to enter or how to proceed, press the F1 key to display the program's on-line help. To display a list of help topics, click the Help button.
For more specific operating instructions, see the following topics:
Entering Field, Crop & Soil Data
Entering Weather & Irrigation Data
Viewing the Irrigation Schedule
Entering Field, Crop & Soil Data
The Field, Crop & Soil Data panel contains several input boxes for entering data, as follows:
Farm Name
Enter a name that identifies your farm, such as "Smith Farms".
Field Name
Enter a name that identifies the specific field you will be irrigating, such as "North 40".
Location
Select the location for your field.
Coastal
Check this box if the field's location is strongly influenced by a large water body. The FAO definition of coastal is as follows: "Situated on or adjacent to the coast of a large land mass and where air masses are influenced by a nearby water body."
Metric Units
Check this box if the field's data are in metric units.
Latitude, Longitude
Enter the latitude of the irrigated field. Longitude is optional, but is also useful if you want to zoom to your field or retrieve forecast weather data.
If you want the program to be able to retrieve U.S. National Weather Service forecast data, you must enter both the latitude and longitude of the location that you want a forecast for. Enter the field's latitude and longitude as decimal degrees. For example, latitude of 40° 30' N would be entered as 40.5. Longitude of 87° 15' W would be entered as -87.25. Important! Be sure to enter a U.S. longitude as a negative number.
Tip: You can determine a field's latitude and longitude in a number of ways. For example, you can use a Web site like this one to zoom in to your crop field on the map, click the field, then copy and paste the latitude and longitude it displays into the scheduler's Latitude and Longitude input boxes:
http://www.spatialrainfallconsulting.com/nexradrain.html
View Map
If you've entered the field's latitude and longitude and your computer is connected to the Internet, you can click the View Map button to launch your browser and zoom to the field's location on a map displayed by the "Clipper" Web app:
Tip: In addition to viewing a map of the field's location, you can also "clip" out the area displayed and download the aerial photograph and other files in a .zip file that can be imported into this free GIS:
http://www.agry.purdue.edu/mmp/mapwindow
Elevation
Enter the field's elevation. If you leave this blank, the program will use a value of 200 meters (approximately 650 feet) in its calculations.
Crop
Select the crop to be irrigated from the list. Important! Alfalfa must be an established crop (second year or older).
Emergence Date
Enter the date when at least 50% of the crop has emerged. Be sure to include the date's year (for example, 5/1/10). If the crop is replanted at a later date, be sure to change the emergence date.
Tip: For perennial crops like alfalfa, enter the green-up date when new leaves begin to grow.
Important! The weather data grid starts with the emergence date. If you change the emergence date once you've started entering weather data, the program will move the weather data up or down so that the new emergence date is on the first row.
Growing Season
Enter the average number of days from emergence to maturity for the irrigated crop. With crops that may be harvested before physiological maturity is reached, enter the standard length to maturity even if harvest may be scheduled early.
Tip: For perennial crops like alfalfa, enter the number of days from green-up to the last cutting.
Projected Yield
Enter a realistic yield goal based on the average of the previous five years for that field.
Rooting Depth
This may vary for different crop and soil combinations, but typical values are:
Alfalfa 4 feet
Corn 3 feet
Dry bean 2 feet
Green bean 1 foot
Melon 3 feet
Potato 2 feet
Soybean 2 feet
Sugarbeet 3 feet
Tomato 2 feet
Wheat 4 feet
Soil Map Unit Symbol
Enter the map unit for the predominant soil in your field. The map unit is a short (6 or fewer characters) identifier from the soil survey.
Import Soil
To obtain soil survey data from the USDA-NRCS Soil Data Mart, click the Import Soil button. The program will display a list of soil surveys. Select a soil survey and the program will display a list of soils in the survey. Select the soil to use and the program will fill in the Soil Map Unit Symbol, Soil Component Name, and Water Holding Capacity input boxes automatically.
Important! You must be connected to the Internet to use this feature.
Soil Component Name
Enter the soil component name for the map unit. Most map units have only one major component. A soil complex will have more than one major component, so enter the one that best represents the field's soil.
Water Holding Capacity
If you're unable to import Soil Data Mart data (see Import Soil above), you will need to calculate water holding capacity using data from your local soil survey. Your local Natural Resources Conservation Service (NRCS) office can help with the calculations. Determine the best-drained soil covering the most acres in the field to be irrigated. In the soil survey table "Physical and Chemical Properties of the Soils," there will be a column labeled "available water capacity." Older soil surveys may have a table "Estimates of soil properties significant in engineering." Available water capacity (AWC) will be listed for each soil horizon as inches of water per inch of soil depth. Find the values that correspond to the soil type you have, then multiply by the rooting length in each horizon, as shown in the example below.
Example: Ormas loamy sand.
Irrigated crop is corn, with 3 feet (36 inches) of rooting depth.
|
Horizon depth (in) |
AWC (in/in) |
Root length (in) |
Cumulative AWC (in) |
|
0-20 |
0.11 |
20 |
2.20 |
|
20-32 |
0.08 |
12 |
0.96 |
|
32-46 |
0.13 |
4 |
0.52 |
|
Total |
|
36 |
3.68 |
For this example, 3.68 inches would be entered for Water Holding Capacity.
Emergence Moisture
Enter the estimated soil moisture content (%) in the top few inches of soil at emergence. For alfalfa, use the moisture at green-up. Average moisture content at emergence is typically between 90% and 100%. If you don't know what the moisture content is, enter 100.
Minimum Moisture
Enter the minimum soil moisture content (%) in the root zone that you will permit before beginning to irrigate. Common values used are 50 to 60. Potato irrigators may want to maintain soil moisture at levels of at least 65%, particularly during critical periods of tuber initiation and bulking. On very sandy soils with low water holding capacity, it may be difficult to manage the irrigation system at very high levels because of the frequency with which irrigation water will be needed.
Irrigation Efficiency
Enter the irrigation equipment's efficiency (%). For example, center pivot systems generally have an efficiency in the range 75-90%, meaning 75-90% of the water going into the system makes it to the crop root zone. Additional efficiencies are given here:
http://www.usbr.gov/pn/agrimet/irrigation.html#Efficiency
If you leave this blank, the program assumes 100% efficiency.
Notes
Enter any notes for your field or data.
Calculation Date
Enter the date (typically today's date) for which you want to calculate irrigation needs. The program assumes the same year as emergence if you don't specify the year; with fall-seeded crops, be sure to include the year.
Calculate
Once you've entered your field information and weather data through the desired calculation date, click the Calculate button. The program checks to see that the data you've entered is valid; if there are no errors, it then calculates the irrigation schedule and displays it in the Preview window.
See also the following topics:
Entering Weather & Irrigation Data
Viewing the Irrigation Schedule
Entering Weather & Irrigation Data
The Weather & Irrigation Data panel contains a grid where you enter daily high and low temperatures, wind speed, humidity, and precipitation and irrigation amounts. Each row corresponds to a different day in the growing season. The columns of the grid are as follows:
Day
This column contains the number of days since emergence. The program considers the emergence date as Day 1.
Date
This column contains the growing season's dates. The emergence date is in the first row (Day 1).
Growth Stage
This column contains the irrigated crop's growth stages. The four growth stages are Initial, Development, Mid-season and Late-season. By default the program estimates the date when each stage begins, but you can override the estimate by right-clicking in this column and choosing a stage from the popup menu to indicate that the stage begins on the currently selected row's date. For a fall-seeded crop like wheat, you can also choose Frozen or Snow-covered to indicate the start of winter periods when no crop transpiration occurs. When you override the default stage, the program displays an asterisk (*) after the stage as a reminder. You can delete an override and revert to the program's default by choosing Reset to Default for any stage that has an asterisk.
For more information about growth stages, see the discussion below.
Temp High
Temp Low
Enter the daily maximum and minimum temperatures in these columns. Try to take temperature readings at the same time each day. If possible, use a max-min thermometer. You can also use daily high-low temperatures reported in local newspapers.
Wind
Enter average wind speed if you have it. If you leave this value blank, the program will assume a wind speed of 2 meters per second (about 4.5 mph).
Humidity
Enter average relative humidity if you have it. Humidity is optional.
Precip
Enter any rainfall that the field received in this column. It's a good idea to install a rain gauge in each irrigated field, as rainfall amounts can vary widely in an area.
Note: If you don't enter a date's precipitation, the program assumes that no rain fell that day. It's a good idea to enter 0 if that's the case so you'll be able to distinguish between rainless days and days when you just forgot to enter anything. If you omit the decimal digits from 0, the days when rain fell (use 1 or 2 decimal digits) will be easy to spot.
Irrigation
Enter total irrigation for 24 hours in this column. If irrigation takes more than 24 hours, split the total irrigation amount between two days.
Notes
You can enter notes in this column about that day's weather or anything else you want to record.
Clear All
If you need to delete all of the weather data from the grid, click the Clear All button. This also deletes any growth stage overrides that you might have entered.
Import File, Import Clipboard, Import Web Service
The Weather & Irrigation Data panel includes three import buttons below the weather input grid.
Use the Import File button to import weather data from a file that you've downloaded from one of these sites. You can also use this button to import weather data from another irrigation data file (.irr), for example if you have more than one field with the same temperatures and you want to avoid entering the temperatures more than once.
When you click the Import File button, the program displays the Select Weather Data File To Import dialog box, where you choose the downloaded file or irrigation data file whose weather data you want to import. The program will then display the Import Weather Data dialog box, where you select what data you want to import. The program then reads the weather data from the file and assigns them to the current file's weather grid.
Use the Import Clipboard button to import weather data that you copied to the clipboard from one of these sites.
When you click the Import Clipboard button, the program displays the Import Weather Data Pasted From Clipboard dialog box, where you paste the data to import (click the Paste button, or right-click in the box and choose Paste, or press Ctrl+V).
Use the Import Web Service button to import data that the program retrieves from a Web service:
- If you select U.S. National Weather Service Forecast, the program inserts forecast weather data for 5 days starting with the current date. You can then calculate an irrigation schedule for any of those days. Note that you must have Latitude and Longitude entered on the Field, Crop & Soil Data panel in order to get a forecast.
- If you select iMETOS ag Weather Station Data, the program will prompt for your weather station's user name and password, then display a list of your weather station(s). Select a weather station to start the data retrieval, then select a subset of available weather data to import.
Caution! When you import data, any temperature, wind speed, humidity and/or precipitation values in the current file's weather grid will be lost, replaced by the imported data.
Growth stages
You can override the program's default growth stages by right-clicking on the Growth Stage column and choosing from the popup menu. The menu choices are as follows:
- Initial. During this stage, less than 10% of the ground is covered by live vegetation.
- Development. This stage begins when at least 10% of the ground is covered by live vegetation.
- Mid-season. This stage begins when effective cover has been reached. This means that most of the soil is shaded due to intermingling of crop leaves. For crops that do not intermingle leaves, this stage would begin when the crop reaches its full height.
- Late-season. This stage begins at the start of maturity.
See also the following topics:
Viewing the Irrigation Schedule
Getting Temperature Data From Other Sources
Using the Command Buttons
Arrayed below the data entry panels is a row of push buttons, as follows:
New
Click the New button to create a new, unnamed irrigation data file. The program displays [New File] on the title bar and blanks the input boxes and weather input grid, then moves the cursor to the Farm Name input box, where you can begin entering your field information. To save the data and give the file a name, click the Save button.
Tip: When the program starts, it creates a new file automatically. You can enter data into this new file, or you can click the Open button to open and edit a data file that you named and saved during a previous session.
Open
Click the Open button to open an existing irrigation data file. The program displays the Open Irrigation Data File dialog box, where you choose the data file you want to open. The program reads the file's data and displays it in the data entry panels, where you can browse and edit the data.
Reopen
Click the Reopen button to open a recently used irrigation data file. The program displays the Reopen Irrigation Data File dialog box, where you select the data file you want to open from the list. The program reads the file's data and displays it in the data entry panels, where you can browse and edit the data.
Save
Click the Save button to save any changes you've made to the current file's data. If the file is new, the program displays the Save Irrigation Data As dialog box, where you enter the name of the file to create for the data. If the current file already has a name (not a new file), the program just saves your data to the file without prompting.
Save As
Click the Save As button to save your file's data under a different name. The file's name appears in the File Name dialog box. Edit the name or enter a new name. Whenever you enter the name of a file that already exists, the program asks you to confirm this before deleting the file's contents.
Options
Click the Options button to view and change the program settings. The program displays the Options dialog box.
Help
Click the Help button to display a list of help topics. This is the same list that's displayed when you click the Contents button at the top of the help window.
About
Click the About button to display the program version number and copyright information.
Exit
Click the Exit button to exit the program.
See also the following topics:
Viewing the Irrigation Schedule
Viewing the Irrigation Schedule
When you click the Calculate button, the program displays the Preview window (assuming there are no errors in your data). At the top of the window are several values that were calculated for your data, as follows:
Schedule Calculated For
Shows the result's calculation date (typically today's date). This is the date you entered in the Calculation Date input box.
Evapotranspiration Rate
This is the evapotranspiration rate for the calculation date.
Soil Profile Moisture Content
This is the estimated soil moisture content on the calculation date, based on soil water holding capacity, rooting depth, evapotranspiration, precipitation, and irrigation.
Amount That Can Be Safely Added
This value is the amount of irrigation water that can be applied without excess runoff or leaching.
If No Rain, You Can Add 1 in. In
Assuming no precipitation, this is the number of days until the profile moisture content reaches the minimum value you specified (for example, 60%), at which time 1 inch of irrigation water is recommended.
Runoff/Leaching Loss For Season
This value estimates the total amount of precipitation or irrigation water that could potentially run off the field or leach below the root zone.
Inefficiency Loss For Season
This is the portion of irrigation water that is assumed lost because of equipment inefficiency.
The Preview window also contains a preview grid containing the results of the daily calculations. You can view the daily calculations by scrolling the grid up and down. As in the weather input grid, each row in the preview grid corresponds to a different day in the growing season. Totals, averages, maximums and minimums are listed at the bottom of the table. The columns of the preview grid are as follows:
Day
This column contains the number of days since emergence. The program considers the emergence date as Day 1.
Date
This column contains the growing season's dates. The emergence date is in the first row (Day 1).
Temp High
Temp Low
This column contains the daily high-low temperatures you entered.
Wind
This column contains the daily average wind speeds you entered.
Humidity
This column contains the daily average relative humidity values you entered.
Precip
This column contains the daily rainfall amounts you entered.
Irrigation
This column contains the daily irrigation amounts you entered.
ET
This column shows the daily evapotranspiration rate.
Runoff or Leach
This column shows the daily amount of excess water that has leached from the soil profile or run off the field.
Soil Mois
This column shows the daily soil moisture in the current rooting depth.
Soil Moisture (relative)
This column shows a simple graphic of the relative soil moisture content. Plus (+) signs indicate that soil moisture was above the desired minimum on that day; negative (-) signs indicate that the soil moisture was below the desired minimum on that day.
At the bottom of the Preview window are three push buttons, as follows:
Click the Print button to print the irrigation calculation results to your printer or to a text file.
Export
Click the Export button to output the irrigation calculation results to a CSV file that you can open with Excel and other programs.
Close
Click the Close button to close the Preview window and return to the data entry part of the program.
Getting Temperature Data from Other Sources
As described in the topic Entering Weather & Irrigation Data, you can obtain temperature values to use for your field from several sources:
- Daily high-low temperatures from your own max-min thermometer.
- Daily high-low temperatures reported in local newspapers.
- From another (nearby) field's irrigation data file (click the Import File button).
If you have Internet access, you can also obtain weather station high-low temperatures. However, you should only use these temperature values as a last resort or if you're missing a block of temperatures.
For example, you could obtain temperature and rainfall data from the Community Collaborative Rain, Hail and Snow Network (CoCoRaHS). Point your Web browser at the following address:
Here are brief instructions on how to use this site:
1. Click the View Data link at the top of the page.
2. Click the Daily Precipitation Reports link.
3. Select your state from the list.
4. Decide which station you want to use and copy and paste the station number into the Station Fields box at the top, then check the Station Number box.
5. Select the range of dates you want and click Search.
Your state may also host Web sites that you can use. For example, the Indiana State Climate Office maintains a Web site where you can interactively display recent temperatures for the weather station(s) nearest your farm. Point your Web browser at the following address:
http://climate.agry.purdue.edu/climate
When you've displayed a table of temperatures you want, print it out for later reference when entering the values into the scheduler.
Note: Tables of temperatures from this site may not be complete for all requested dates. They may also contain temperatures from more than one station; pick the station that best represents your farm's weather.
Importing Weather Data
To import data from Weather Underground:
1. Point your Web browser at the following address:
2. Enter the location you want in the box at the top of the page.
3. Scroll down to History and Almanac and click the View button.
4. On the History page, click the Custom link.
5. Select the range of dates you want and click Go.
6. Scroll down to the Observations table and click the Comma Delimited File button below the table
7. Once the weather data has been displayed, choose File | Save As in your browser and enter a name to use for the downloaded file (with a .txt file extension). Select Text File as the file type to save. Tip: Instead of downloading, you can copy the data to the clipboard by choosing Edit | Select All, then Edit | Copy in your browser (or press Ctrl+A, Ctrl+C).
8. To import from a downloaded file, click the Import File button; to import from clipboard data, click the Import Clipboard button.
To import NEXRAD rainfall data:
1. Point your Web browser at the following address:
http://www.spatialrainfallconsulting.com/nexradrain.html
2. Using the map, zoom in on your farm or field, then click the location that you want NEXRAD rainfall data for.
3. Select the starting and ending dates at the bottom of the page and click Submit.
4. Once the rainfall data has been displayed, choose File | Save As in your browser and enter a name for the downloaded file (with a .txt file extension). Select Text File as the file type to save. Tip: Instead of downloading, you can copy the data to the clipboard by choosing Edit | Select All, then Edit | Copy in your browser (or press Ctrl+A, Ctrl+C).
5. To import from a downloaded file, click the Import File button; to import from clipboard data, click the Import Clipboard button.
To import data from NOAA:
1. Point your Web browser at the following address:
http://cdo.ncdc.noaa.gov/qclcd/QCLCD?prior=N
2. Select your state and click Continue.
3. Select the weather station closest to you and click Continue.
4. Select the month to download and click Continue.
5. Click the ASCII Download (Daily Summ.) button.
6. Once the weather data has been displayed, choose File | Save As in your browser and enter a name to use for the downloaded file (with a .txt file extension). Select Text File as the file type to save. Tip: Instead of downloading, you can copy the data to the clipboard by choosing Edit | Select All, then Edit | Copy in your browser (or press Ctrl+A, Ctrl+C).
7. To import from a downloaded file, click the Import File button; to import from clipboard data, click the Import Clipboard button.
To import your own data file:
1. You can also import a Comma Separated Values (CSV) text file that you create yourself. This file must include the following column headers in the first line. The order is not important as long as the data are in the same order as the headers. You can also include Wind Speed and Humidity if you have them.
Month,Day,Year,Precip,Max Temp,Min Temp
2. Weather data starts on line 2, with one day of data per line. For example, a line of weather data might look like this for May 8, 2009, where 0.12 inches of rain fell and the high temperature was 80 and the low temperature was 52:
5,8,2009,0.12,80,52
3. You can create this file with a text editor. You can also create it with Excel by saving your data as a CSV file.
4. To import your data file, click the Import File button and select the CSV file.
Tip: If you need to indicate the units for your data, you can also use these headers:
Month,Day,Year,Precip (inch),Max Temp (degF),Min Temp (degF),Wind Speed (mph),Humidity (%)
Month,Day,Year,Precip (mm),Max Temp (degC),Min Temp (degC),Wind Speed (mps),Humidity (%)
Notes for International Users
If you're irrigating fields that are not in the continental U.S., here are some tips for operating the program:
Location
Select the International location rather than a U.S. state.
Metric Units
Normally you'll want to check this box.
View Map
With the International location, the program uses Google Maps to zoom in on your field.
Import Soil
This button only works with U.S. soil survey data. To estimate your soil's water holding capacity, select a value from the following table (in mm/cm) and multiply it by your crop's rooting depth (in cm):
Coarse sand 0.58 mm/cm
Fine sand 0.75
Sandy loam 1.00
Fine sandy loam 1.25
Loam 1.50
Silt loam 1.67
Clay loam 1.83
Clay, peat, muck 2.00
For example, with a uniformly loamy soil and a crop that has a rooting depth of 50 cm, enter 75 in the Water Holding Capacity box (1.50 x 50).
These values were adapted from the following source:
http://www.usbr.gov/pn/agrimet/irrigation.html#Soil
Import Web Service | U.S. National Weather Service Forecast
This choice can only retrieve forecast data for U.S. locations.
About the Authors
If you have agronomic questions, please contact:
Dr. Brad Joern
Agronomy Dept.
Lilly Hall of Life Sciences
Purdue University
West Lafayette, IN 47907-1150
U.S.A.
Phone: (765) 494-9767
FAX: (765) 496-2926
E-mail: bjoern@purdue.edu
If you have software questions, please contact:
Phil Hess
Agronomy Dept.
Lilly Hall of Life Sciences
Purdue University
West Lafayette, IN 47907-1150
U.S.A.
Phone: (765) 494-8050
FAX: (765) 496-2926
E-mail: pjhess@purdue.edu
Options
When you click the Options button, the program displays the Options dialog box, where you can change several settings that affect how the program operates, as follows:
Popup Help Hints For Mouse Position
Display Help Hints On Status Bar
The program uses these two check boxes to determine what sort of help hints to display, as follows:
- If both boxes are checked, the program displays a help hint on the status bar whenever the mouse is positioned over an input box or push button.
- If only the first box is checked, the program displays a help hint in a small rectangle near the input box or push button.
- If only the second box is checked, the program displays a help hint on the status bar for the input box or push button where the cursor is.
- If neither box is checked, the program does not display any help hints.