I have been advised to treat my lawn with nitrogen to kill off some of the weeds that are growing through, the majority of the lawn is weed at the moment but the grass is still there. Which product will do the job? I have a dog who uses the lawn so any product I use needs to be pet safe and quickly absorbed, slow release probably won't work for that reason. What would you advise? 

• Feeding your lawn along with regular watering and mowing on a high setting will crowd out invading weeds.
• Grasses are not tolerant of the high urea that comes from dog urine, so there are always going to be bare patches in your lawn unless the dog can be trained to go in one area - treats always help encourage dogs to do this. 
• Liquid feeding is the quickest way to get fertiliser onto your lawn, and is quickly absorbed.
• Tui LawnForce All Purpose lawn fertiliser has a high nitrogen ratio (N20) and is a very small prill, apply  to a dry lawn, then water in.
• LawnForce All Purpose lawn fertiliser a pet friendly slow release fertiliser. 
• Keep pets off until the lawn is dry as the iron content in LawnForce All Purpose slow release lawn fertiliser will stain porous surfaces and you will end up with paw prints on the deck or pathways.
• Once dry, it is 100% safe to use the lawn area.