Still Required This Year wrong in modals

[raarielgrace]

Describe the Bug
In the flow used in the demo, the "still required this year" numbers were consistently wrong.

** Steps To Reproduce**
Steps to reproduce the behaviour:

1. Add an animal or imported manure.
2. Add a crop, ideally one that consumes a lot of nutrients. (berries with a leaf test of 0.08% P and 0.1% K is a good one)
3. In Calculate Nutrients, click Add Manure and input values.
4. Upon clicking "Calculate", the numbers for "Still Required This Year" are unchanged from the beginning balance row.

Another flow:

1. On Calculate Nutrients, add a Fertigation. Input 1 application per season and hit calculate. Increase this to 2 applications per season and hit calculate. "Total Applied Nutrients" will increase, but "Still Required" will not decrease.

Additional context
Please double-check that the Fertilizer modal works as expected. Also made sure that the nitrogen for applying manure in a previous year to the field is factored in to each modal's calculation.