My pump works well but since I added sprinklers for a new lawn the well kicks in for 1 minute, then off for 30 seconds, then on for 1 minute and this recycling continues for 30 minutes each day. How can I adjust the well pressure switch (two adjustment springs) so that the pump will just stay on for the 30 minujtes it waters the lawn each day??

Pump switch works on pressure not time.
Apparently you pump is capable of pumping more water than the sprinklers put out. That "extra" water goes into the tank. Apparently it takes one minute for the pressure in the tank to build to cut off pressure. It then takes 30 seconds for the sprinklers to use that water and the pump comes on again.

To prevent the frequent cycling get a bigger tank or add a sprinkler head.

Tank size could sure be a problem. Could also be a bladder tank with a blown bladder which is starting to become waterlogged.

HK nailed it in saying that the switch is not your problem.