Fertilizer Optimizer Tool

This free Android app helps you to use fertilizer more efficiently to optimize your fertilizer investments. It is based on robust crop response functions.    

You can use it to: 

  • Calculate the most profitable combination of fertilizers to purchase 
  • Find information on crop and site-specific application rates 
  • Tailor results to the farm by including integrated soil fertility management (ISFM) practices to the recommendation 
  • Send results to the farmer via SMS or WhatsApp or other sharing options available on your device. 
  • Shows potential monetary gains


  • Free to use 
  • Easy to use 
  • Works offline 
  • Languages: English, French, Portuguese 

I have used fertilizer for about five years now. Each season, I used to spend about UGX450,000 to buy 50kg DAP and 50kg Urea and 50kg TSP for my maize and groundnuts. I have used FOT for 2 seasons now and I have realized that I have used significantly less fertilizer and money than before yet the production is comparable. Last season, I invested UGX100,000 for 1 acre of maize, 1 acre of groundnuts and ½ acre of soybean. The FOT output was 22kg DAP & 22kg Urea for maize, 11kg TSP for groundnuts, and 11kg urea for soybean. For maize, I obtained 16 bags (each 100kg) compared to 10 bags before. This shows that I was wasting my resources.

Paul Okingok, Farmer, Karwok Village, Molo Sub County, Tororo District, Uganda

Who is it for?

The Fertilizer Optimizer Tool is free for everyone to download and use. It is particularly useful for: 

  • Agricultural extension workers 
  • Agro-input dealers 
  • Farmers 

The Fertilizer Optimizer app can provide calculations relevant to 13 African countries. These are Burkina Faso, Ethiopia, Ghana, Kenya, Malawi, Mali, Mozambique, Niger, Nigeria, Rwanda, Tanzania, Uganda and Zambia.

What you'll need

  • An Android smartphone or tablet with enough storage space for the app
  • Access to the internet to download the app from the Google Play Store (the app works offline once downloaded)
Occasionally, CABI will release updates for the Fertilizer Optimizer app. To update your app, you need a stable internet connection and additional storage space on your device.

How it works

The Fertilizer Optimizer app helps you to use fertilizer more efficiently so you can optimize your fertilizer investments.  

The app will ask you for information on:  

  • crops grown 
  • area planted 
  • expected crop sale prices 
  • fertilizer costs 
  • budget you have to invest in fertilizer products  

Based on robust crop response functions, the app calculates the most profitable combination of fertilizers to purchase and advises you on crop and site-specific application rates. The app also takes into account any integrated soil fertility management (ISFM) practices to further tailor the fertilizer recommendation to your farm. 

  1. Choose the language and country 
  2. Enter the agro-ecological zone (AEZ) of the farm 
  3. In the app, scroll through the list of crops and selects all of the crops the farmer will grow in the season and clicks save 
  4. Select your preferred unit of area and then enter the area allocated to each crop and the selling prices that will be achievable in the coming season 
  5. Select the fertilizer(s) available in the locality, e.g. triple super phosphate (TSP), and save 
  6. Enter the likely prices for the selected fertilizers 
  7. Enter the amount of money the farmer has to invest in fertilizers

After entering the required information, click “Calculate” to optimise. Depending on the financial level, and the estimated price of the ready crop at the end of the season, the output example will display as follows:  

  • Total expected net returns 
  • Total fertilizer needed per type 
  • Fertilizer needed per crop 
  • Application rate per fertilizer type (kgs/acre) 
  • Expected average effects per acre  
  • Yield increased per crop (kgs/acre) 
  • Net Returns per crop 

In practice, manure application and crop rotation are good agricultural practices that add nutrients to the soil. For the most accurate results, previous practices used on the land/farm should be taken into account. The recommendations will change accordingly, as will the total fertilizer type needed per crop. This is because of the existing nutrients in the soil. 

On the app, select a container and fill in the required spacing, the click “calibrate fertilizers” to find out how far the fertilizer in the selected fertilizer container will go. If multiple crops have been entered, calibrate for each crop.

Results can be shared via SMS, WhatsApp or other sharing options available on your device.

Why CABI created the Fertilizer Optimizer app

We’ve created the Fertilizer Optimizer app so that extension workers and farmers can have free access to fertilizer advice, on mobile devices. The app runs offline allowing you to perform optimization calculations in the field. The app will periodically check our servers for updates to the tool.

Related Tools