9 months ago my tarmac drive was excavated and the drive and lawn re-shaped. An area (approx 10' x 10') that had previously been under tarmac was covered with a layer of top soil and grass seed applied. Pigeons feasted themselves on the seed and further seed had to be applied However, the grass has failed to thrive, there is a lot of bare soil and the surviving grass looks yellowish and has failed to spread. Is it nutrient deficient? Should I feed it and, if so, with what? Could the soil be toxic?? Despite being north-facing, the lawn gets quite a lot of sun but a large weeping willow obviously soaks up a lot of moisture. Any advice will be much appreciated.
The ground that you planted on was most likely quite compacted, simply placing topsoil on this surface may not have been enough to ensure your seed could take hold and grow.
I would recommend a soil test. Your County Extension Office can help you with a soil test. I would also recommend that you confer with them on the best grass seed to use in your growing zone.
Here are some articles that will help you and I also have included a link to help you locate your nearest Extension Office.