Why do farmers plow the field before sowing the seeds?

The land does not need to be ploughed before crops are planted.

Before modern herbicides ploughing was used to reduce weeds.

Ploughing releases greenhouse gasses and allows soil moisture to escape.

There is a growing trend towards "Direct Drilling" into unploughed land and it has been suggest that no till farming will be considered to be sequesting carbon and eligible for carbon credits in the future.