Why are lime recommendations not what I expect after changing soil test pH?
Problem Description:After entering the crop rotation into a field, the user goes back and modifies the soil test information, changing the pH. Since pH affects lime recommendations, it's natural to expect this change will affect the lime application amount shown on the soil test report, but it does not. When the user revisits the field's crops and edits them in the Plant Crops screen, hitting the calculate button doesn't produce the expected lime recommendations.
Answer: This is a complex fake-out that occassionally surprises people. The problem is that NutMan automatically inserts lime applications in the plan when you OK out of the Plant Crops screen. At that time it calculates the lime recommendation based on the soil test pH and any lime applications already applied to the field. If you go back and change the field's pH later, NutMan doesn't automatically remove or change these automatically inserted lime applications. This is why just changing the pH doesn't change the lime amount shown on the soil test report. Then when you edit the crops in the Plant Crops screen and press the calculate button, it does recalculate the lime recommendation. But it takes into account those automatically entered lime applications that are still in the plan from your first trip through this screen. If you don't realize that, the calculated recommendation may be different than you expect.
Basically, the automatic lime application feature works intuitively for the normal sequence of events: set field features => set soils => set soil tests => add crops. But if you loop back and change the soil test pH after NutMan has already automatically inserted lime applications for your crops, it can be confusing. At one time, we intended to make the program smart enough to automatically whipe out and redo the lime applications in a field if the soil tests are modified. But since the user can manually add, remove, and edit lime applications in the Lime tab of the Nutrient Edit screen, this raised the prospect of NutMan automatically undoing things the planner had deliberately set. And we were never quite comfortable with that. So as things stand now, it's ultimately up to the planner to make sure the lime applications are what they should be. The planner has complete control of the lime applications in the plan through the Nutrent Edit screen.
If you've changed pH in a field and you want to use NutMan's automatically calculated and inserted schedule of lime applications, this is still possible. But you have to help the process along. First, you have to clean up any lime applications based on the old pH value by going to the Lime tab of the Nutrient Edit screen and removing any lime applications scheduled for this field. Then go to the Plant Crops screen and revisit each of the field's crops in order from first to last. At each crop, click the "Calculate" button, and OK out. NutMan will calculate lime recommendations based on the new pH and insert lime applications into the plan as needed.
