soil around lose weight. Why? Experiement of the nature of photosynthesis. If you plant a tree seddling in a barrel and if you give it water regularly, it wil gain weight and the soil into the barrel lose weight. Why this happens?
Thank you very much

Because the tree absorbs minerals out of the soil. As the tree grows it will increase in mass, while the soil will lose mass due to mineral loss.

It absorps Nitrogen, Sulphates and so on, thats why you need fertilizer( but only rarely)