Use non char as a control and run a ferililizer rates studies.

Also to get the char rate us a calculate exponential rate of zero char, 1,000 kg/har

10 ,000 kg;/ha and 100,ooo kg/ha. Get your responses and fine tune to a minimum optimized rate.

You can use a factorial design will 4 replicates.

Consult with a statistic design expert for the exact design arrangements.

2.5 L pot is small for maize if you want to go to end to have fruits

I would use a bigger pot too. About fertilization, I can only tell you that I would use a slow release fertilizer as Osmocote.

Thank you all for your suggestions!