Improvement in food resources.
Increasing productivity simply means getting more output from same input. For eg, growing more crops this year than a year before from the same land, or getting more mileage from same vehicle etc.
Productivity is needed because population is increasing, and resources we have are limited, so to cope up with increasing needs.
Productivity ensures that resources will not be extinct and be available for coming generations.
Productivity is cost and time effective. So, any system or industry will try to achieve that.