Repairing conifer soil damage
We moved into our house last Christmas. The garden is north facing with 50' of lawn and had large conifer trees along the west fence (six in total, approx 8-10 m tall), so the garden received next to no direct sunlight. I've chopped down the trees, scarified extensively, reseeded and overseeded with grass seed and now the lawn is starting to come together. However, the soil is noticeably poorer at the bottom half of the lawn that's nearer the old conifer trees. It's dry and crumbly and has far fewer worms. Consequently (coincidentally?) the grass grows much slower here and is less lush. There are conifer roots just below the surface of the lawn although the stumps are dead. I assume the conifers have stripped the soil of nutrients over many many years. I don't want to rip up the lawn to nourish the soil, can I add anything to the lawn to improve soil quality? Does it require repeated applications over many years? I read about adding a thin layer of peat moss but am concerned about the ecological impact. I should stress that I'm concerned about the soil quality rather than the growth of the grass. I can add chemical fertilisers if I'm that bothered about the grass, but I really want to address the underlying issue. I look forward to hearing your thoughts.