I have 48 lettuces which were judged by their weights (grown in separate pots).

Half of these pots used normal soil, the other half a very sandy soil (which significantly reduced lettuce weights).

Half of these pots (spread equally between soil type) also were mixed with charcoal, the other half not. (Charcoal slightly increased lettuce weights).

I don't think ANOVA is appropriate and it gave out not significant results... I want to find the significant improvement from using the charcoal.

My advisor is now unreachable but previously mentioned a paired t-test but I would have thought this is inappropriate considering the different soil mediums right?

Basically I need to come up with a graph with error bars with (normal without charcoal, normal with charcoal, sandy without charcoal, sandy with charcoal) and some significance of these.

Thank you very much for any help,

Regards,

Marcus