# Fertilizer Calculator



## wessneroo (Jan 22, 2019)

I made a simple tool to calculate fertilizer rates to meet my soil test recommendations and thought I'd share in case anyone doesn't already have something similar. My local university advises in lbs/1000sqft but it can be difficult to find products that exactly match the numbers they recommend so the tool lets me get "close enough" using products that are cheap/plentiful in my neighborhood or that I already have in stock.

I've been using this for the season but this is my first time sharing so let me know if there are any bugs or suggestions.

https://docs.google.com/spreadsheets/d/1c8fG4HWXazXH7jWx_6p9NKWI_je2QT9hAZA_JlB8dSc/edit?usp=sharing

https://docs.google.com/spreadsheets/d/1c8fG4HWXazXH7jWx_6p9NKWI_je2QT9hAZA_JlB8dSc/edit?usp=sharing

Instructions:
0. Download the spreadsheet locally or save a copy to your Drive. In general, you'll only need to change values in colored cells, but the cells with formulas (white) are left unlocked in case you want to change anything. If anything gets messed up you can download a fresh copy from the link. 
1. Enter your lawn size in L2 (blue).
2. Enter your soil test's recommendations in the "Target" section (red). 
3. In "Application Plan" enter the names of the products you want to try to use in column B and add their N/P/K numbers in columns E, F, and G (yellow). 
4. Guess and check with values in column C (green) until the "Deviation from Target" values in row 31 are close enough for you. 
5. Now you have rates to meet your soil test's recommendations without having to use their recommended products.

Example (shown in sheet):
This spring, the university advised 3lbs/1000sqft of 0-46-0 and 6lbs/1000sqft of 15-0-15. Problem is, neither of those exist in my area. I entered the N/P/K numbers for the fertilizers my local stores regularly stock and played around with rates until I found a close match. The sheet shows that 8.8lbs/1000sqft of 10-10-10 and 1.2lbs/1000sqft of 0-45-0 gets me within 3% of the recommendations, which is close enough for my very unperfect lawn.


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