Equations Tab

Equations

The following section describes how to:

  • Choose an Equation

  • Setting VRT Equations

  • Edit an Equation

  • Set Direct Rates

  • Set Min and Max Rates

  • Set Low Rate Adjustments

Choose an Equation

After selecting the fertilizers to use in the prescription, choose the equations that will be used to calculate a fertilizer recommendation.

  1. Click on the dropdown arrow next to each fertilizer source and choose an equation.

    • A Zoned Field is pictured below. If a grid soil test has been associated to the field, and is available in the Soil Samples tab, users may choose to run the equation on either the grid or zone soil test. For example, mobile nutrients could be sampled by zone while non-mobile nutrients are grid sampled.

  • A Grid Field is pictured below. Notice Use Grid is checked by default.

NOTE: To change the list of available equations, See Settings > Equations.

Setting VRT Equations

Users can use VRT equations for both Nitrogen and Phosphorus. These are advanced equations that rely on variable factors. This allows Prescription Builder to use variable equations on different zones.

Nitrogen

1. Choose VRT from the list of available Nitrogen Equations.

2. The Nitrogen Use Management window opens. Enter the Nitrogen use efficiency for each zone being applied. Click Confirm.

3. The rates can be changed by clicking the Mgmt button.

Phosphorus

1.Choose VRT from the list of available Phosphorus Equations.

2.The Phosphorus Management window opens. The soil test type is listed with the soil test value (P-Olsen in this example). This window allows users to Build or Maintain the current level of Phosphorus for each zone within the field. When all the parameters have been set, click Confirm. The rates can be changed by clicking the Mgmt button.

Edit an Equation

Equations can be modified to meet user needs.

1. Next to an equation that has been selected, click the Edit button.

2. Use the Edit Equation window to make necessary changes. Click Confirm when complete. Values can be entered into the boxes (outlined in red below) to test the equation.

NOTE: Changes made here will only apply to the current prescription. Long-term changes can be made it in Settings > Equations, or by updating a Template.

Set Direct Rates

Direct Rates allow specific fertilizers to be spread at a predefined rate. Direct Rates are used when blends are being applied to the field or when a grower wants to apply a product to the field that may not be called for. Use the following procedure to apply a direct rate.

NOTE: Direct Rates override the equation.

1. Click on the blue Direct Rate button next to the corresponding nutrient.

2. The Edit Direct Rates window appears. Enter the direct rates for each zone. Direct rates don’t need to be the same for each zone, nor does each zone need a direct rate. Auto Fill will apply the same rate to all zones. Click Confirm when finished.

NOTE: The rates entered are in pounds/gallons of product.

1. The Direct Rate button will now show which zones have a Direct Rate.

Set Min and Max Rates

Minimum and Maximum rates can be set for each nutrient source. Setting these rates will not allow any zone to apply more than the maximum rate or less than the minimum rate. To use a Min or Max rate, enter any value into the box.

Set Low Rate Adjustments

Setting a low rate adjustment works as follows. Any value that is lower than the number entered in the first box, but greater than 0, will be given the value of what is in the second box. In this example, any rate under 15 pounds will be applied at a rate of 15 pounds. Low rate adjustments are typically set because of equipment limitations.