I did a little experiment to grow watermelons under the same environmental conditions in the soil and the hydroponic method.
I bought 8 watermelon seedlings at the nursery. 4 I planted in soil and 4 in hydroponic containers.
On the ground I did not make any preparation or give fertilizer – only water. In hydroponics I started with the kratky method, set the pH to 5.8 and added a basic hydroponic fertilizer.
At first the hydroponic led impressively. The growth was much faster than the soil. After a while the plants in the hydroponic containers began to look unhealthy. I decided to add an air pump to add oxygen to the watermelon roots. It helped a bit but in the end no watermelon from the hydroponic system came to pick. I guess it has to do with the composition of the fertilizers.
On the soil it went better. 4 watermelons were great (very sweet) the rest was not so tasty.
Summary – the growth in the soil won in this round. Next year I will try again. This time with an air pump from day one and with a different fertilizer composition in the hydroponic system. I will update with the results next year so stay tuned