Give reasons for the following:

Seeds should be sown at the right depth.

Give reasons for the following:

It is important to irrigate the fields.

Give reasons for the following:

Fruits, vegetables and grains should be thoroughly washed before use.

Give reasons for the following:

Farmers prefer to grow leguminous crops alternatively with cereal crops in their fields.

Give reasons for the following:

Manure is slowly absorbed by plants.