Question

reena segregated the waste at home and put the biodegradable waste in pot containing soil. she leaves it for 15 days and uses that soil for her plants in the garden. why do you think she used that soil

Answer 1

She used that soil because of presence of organic matter in the soil which increased it's fertility, water retention capacity and made it porous.
All these factors are good for the growth of plant.

Answer 2

The domestic waste is very useful as it can convert to manure easily and can also use for harvesting. It is very good for plants as it gives a very high amount of nutrients to plants.  

Therefore when Reena segregated the waste at home and put the biodegradable waste in pot containing soil that made the soil rich in nutrients and very good for plants.  

The conversion of domestic waste to nutrients take time approximately 15-20 days.