- Author: Michael D Cahn
Now that you have a ranch established in CropManage, you are ready to add plantings to the ranch. Each “planting” in CropManage consists of a set of tables for keeping records of soil tests, irrigations, and fertilizer applications associated with a specific crop planted on a ranch.
Each planting is unique, and should correspond to an actual crop planted on your farm or ranch, with a specific establishment and harvest date, field location, and acres. The planting also requires information about the irrigation system, crop type, and previous crop residues. This initial information is used later by CropManage to provide decision support on irrigation and fertilizer applications. Once a planting is established in CropManage, there is no need to reenter the initial information unless updating is needed.
After selecting a ranch, a list of current plantings will be displayed in “Ranch Home“ (Fig. 1). Selecting new planting below the planting list table will navigate to the “new planting form”(Fig. 2).
Figure 1. A table in ranch home displays a list of current plantings. Select “new planting” below the summary table to start a begin editing a new planting.
Give the planting a name and select a crop Fill in the name of the planting, start (first irrigation) and end dates (last harvest) of the crop, year, and select the field or lot from the pull down menu. The soil type of the lot is used for irrigation, soil test, and fertilizer calculations. If the lot is not listed, then the virtual ranch owner needs to enter the lot information in the “edit ranch” form. Also select the crop type and planting configuration from the pull down menu.
Select save after all information is entered and a new window will display for entering additional information (Fig. 3). In many cases, default values are provided in the forms that are typical for coastal vegetable crops. When in doubt, use the default values.
Previous crop CropManage estimates N contribution from incorporated residue of the crop when calculating the nitrogen fertilizer needs of the current crop. Select the type of previous crop that preceded the current planting (Fig. 3). If the previous crop is not displayed in the pull down menu, then select a crop that approximates the amount and type of residue observed. If no crop preceded the planting or if the interval was more than 2 months, then select “no crop residue within 2 months.” Change the interval between residue incorporation and planting from the default value (30 days) to the actual value.
Figure 2. To begin a new planting, enter the name of the planting, crop type, first irrigation and end dates (harvest date) of the crop into the new planting form.
Figure 3. Enter previous crop information so that CropManage can estimate N contribution from incorporated plant residues.
Figure 4. Irrigation system information is entered into the new planting form for calculating the volume of water (inches) and time to irrigate.
Irrigation information CropManage uses information about the irrigation system for calculating the amount of water and time to irrigate (Fig. 4). If drip and sprinklers will be used for irrigating the crop, enter values for both types of irrigation methods. Currently, CropManage does not support furrow irrigation.
The application rate of the irrigation system in units of inches per hour must be entered to convert the volume of water applied to application time. Default values are provided in the form, but these values may vary greatly from the actual rate if the irrigation system is atypical. A calculator for estimating the application rate appears when the cursor is placed in the application rate form for drip or sprinkler (Fig. 5). Application rate can be estimated for sprinklers by entering sprinkler head type, lateral pipe spacing, sprinkler head spacing, nozzle pressure, and nozzle orifice diameter (Fig. 5). Application rate can be estimated for drip by entering the flow rate of the tape, bed width, and number of tapes per bed (Fig. 5).
Leaching fraction for salt management A leaching fraction value greater than default value of 0% should be entered if the irrigation water has a salinity concentration that would reduce yield (Fig. 4). Bulk salinity is measured with an electrical conductivity (EC) meter in units of deciSiemens per meter. EC increases with salinity content of water or soil. The salinity threshold of irrigation water at which yield is reduced for lettuce is approximately 1 to 1.5 dS/m depending on the specific types of salts in the water. A leaching fraction that adds an additional 15% to 30% more water to the irrigation recommendation would be typical if the irrigation water has salinity levels in the range of 1 to 2 dS/m.
Figure 5. Calculators for drip and sprinklers can be used to estimate the application rate of the irrigation systems.
Irrigation distribution uniformity The irrigation recommendations for the planting are adjusted for non-uniformity of the irrigation system using values entered for distribution uniformity (DU) of the drip and sprinkler systems. Distribution uniformity is the ratio between the average application volume for the driest part of the field (typically the driest quarter) and the average application volume of the entire field:
The DU of an irrigation system that provides perfect uniformity would be equal to 100%. Typical default values are provided for sprinklers and drip but they should be adjusted to reflect actual conditions of the crop. Drip tape that has been retrieved and reused for more than 8 crops may have a DU substantially less than 90%. Likewise, sprinklers that are operated under high wind conditions may have a DU lower than 75%.
Two different DU values can be entered for the sprinkler system if different equipment configurations are used for the germination and post establishment phases, or to reflect different tolerances for dry zones in the field during germination and post-establishment. During crop establishment (germination or transplant establishment), one may want to assure that dry areas in the field are minimized by lowering the DU value. A DU corresponding to the driest tenth of the field typically will be 10% to 15% less than a DU for the driest quarter of the field.
Total amount of nitrogen taken up by the crop The N fertilizer recommendation is based on an N uptake curve for each crop type and planting configuration. This curve can be adjusted by increasing or decreasing the total N uptake value or increasing the interval between the first irrigation and the harvest (end of crop). For each crop type and planting configuration supported, CropManage provides a default value for the total amount of nitrogen that the crop will take up in units of pounds of nitrogen per acre (Fig. 6). The default values are averages of measurements from commercial fields. The value may need to be increased or decreased to reflect factors such as a lower or higher plant population, smaller or larger than normal sized plants, or varietal differences.
Figure 6. Planting form entries for N fertilization recommendations: crop total N uptake, maximum fertilizer N recommendation, and days between consecutive fertilizer events.
Two other entries needed for making the fertilizer N recommendation are the maximum N recommendation and a default value for the days to next fertilization. To prevent fertilizer N recommendations that are excessive due to incorrectly entering information, CropManage includes a maximum N recommendation value that limits the amount of N fertilizer recommended. This value may need to be increased for plantings where only 1 or 2 nitrogen fertilizer applications are made. An estimate of the days until then next fertilizer application is needed to predict future N uptake of a crop. A default value can be set in the planting form, but adjusted later when fertilizer events are entered.
Flow meter data retrieval Water applications can be monitored using a flow meter capable of producing an electronic output signal that can be recorded with a datalogger. Currently, automated retrieval of flowmeter data to CropManage is limited to using Campbell Scientific™ dataloggers equipped with cell phone modem or radio communications. CropManage can be configured to automatically retrieve flowmeter data for a planting at hourly intervals by entering the datalogger file name and the areas monitored under drip and/or sprinkler irrigation (Fig. 7). Leave these entries blank if no flow meter will be used with the planting. Contact Michael Cahn (firstname.lastname@example.org) or Barry Farrara (email@example.com) for further details on how to use flow meters for monitoring water applications using CropManage.
Figure 7. Form entries for flowmeter information and lot latitude and longitude coordinates.
Lot coordinates The lot is the actual planted area within a field. Because some fields are split into several plantings, lots can be small than the field area. Latitude and longitude coordinates of the planting (lot) can be entered in the planting form (Fig. 7). A mapping tool will appear to assist in locating the field when the curser is placed in the Lot Coordinates box (Fig. 8).
Figure 8. Mapping tool for finding the latitude and longitude coordinates of a lot
Don’t forget to save! When satisfied with all planting entries select save at the bottom of the planting form. Edit entries at anytime to update planting information.