Grass dying

Thanks.

Looking up the properties of concrete/cement dust, I see that it should be degraded to calcium carbonate by now and hence the soil quite alkaline. I’m hoping my PH meter arrives today so that tomorrow I can check the PH of the different areas. Whilst it won’t be as accurate as a professional one, as long as it’s consistent then I can compare the healthy and unhealthy areas.

Getting ahead of myself a bit, I’d want to minimise the amount of soil replaced. Not only is there a cost and effort to digging out and replacing the soil but the steps’ awkward 12 ft drop makes moving soil to the lawn a long PITA. I’d therefore probably first try to lower the PH of the yellowed areas using an acidic fertiliser if that would work. Whilst articles on new lawns suggest putting down 6” of top soil, could I get away with less on the yellow areas and, if so, what shorter depth would be fine?

 

Grass needs a minimum 4" depth of soil to develop roots and maintain healthy growth. Putting less than 6" of soil on the damaged areas would risk the roots coming in to contact with the lower soil, which would probably put you back at square one - starting all over again.

 

Dig out some soil and pot it up then try growing some cress in it indoors.
Used to be the way of detecting dodgy contaminated soil.

Cress only takes a few days to germinate on a warm window sill.

 

My PH meter finally arrived. It gave consistent readings when tested repeatedly in the same patch of soil, so even if not accurate should be fine for comparing different areas

The soil in the flower beds gave a PH of 7.0 from the surface to 6” down, as did that in the bare patch, just within the 6.5-7.0 limit that I see recommended. The yellow patches had a PH of 7.0 - 7.5, on the high/alkaline side but not massively so.

 

Hi
The white grass, does it look like it’s got a White powdery finish or do you see any type of white webbing covering the grass?

 

Thanks. Apologies for the delay in responding.

There’s no sign of anything other than the yellow grass and dead patches. No powdery finish, no webbing, no unusual elements.

 

I replaced the topsoil in the affected areas and reseeded. I’ll update this next year when the area has gone through a full year’s cycle.

Thanks again, all, for your help and interest.