Question

Q. Why weed should be removed ?

Answer 1

Unwanted crops or plants which occupy fields and generally compete with normal or wanted plant species or crops. They Take nutrients out of the soil, most vital ones such as magnesium, phosphorous, nitrates, etc.
Thus making the humus (of the soil layer) infertile and degrading the quality plus requirements needed for next upcoming plants.
It is usually caused due to a foreign pollen grain introduced by an animal, Wind Pollen, or through any other medium which carries it.
If it is seen, should be uprooted quickly, after that using chemicals (specifically for pollen grain removal) to kill it.

Answer 2

Answer:

Weeds compete with the crop plants for water, nutrients, space and light and thus affect the growth of the crop. So, they should be removed.