Black patches on earth in lawn (grass unaffected)

andy625uk

Can anyone tell me what's happening to my lawn. For the last couple of years I've noticed black patches appearing on the earth under my grass. It looks like someone has dropped small patches of compost on the grass. The grass is growing ok, and lovely and green, but as time goes on, the patches seem to be growing. 

Fairygirl

No idea really Andy. Are they related to the bare patches, and how widespread is it?

Could something be scraping at the ground? I have visiting hedgehogs who scrape at a few baldy patches of grass to get at whatever's underneath, and the patches then look like fresh soil, and very similar to yours.

Obelixx

Difficult to see exactly what it is or its texture.   Have you felt it?  Is it slimy or dry?   Could be black slime mold in which case you need to do some work to aerate your lawn or it could be algae or lichens or liverworts which also indicate poor drainage.

In any case, I can see plenty of thatch which would be best raked off so, depending on the size of your lawn, use a spring-tined rake to lift all loose material and debris or else buy or hire a scarifier to do it for you.   Then you need to push a garden fork in vertically and as deep as you can and wiggle it back and forth to open up the holes it makes.  Work backwards so as not to compact the holes with your weight and make them at intervals of 6" or so across the whole lawn.  Then you can pile on dollops of shrap sand (not damp builders' sand) and sweep it across and down the holes.  The larger grains will keep those holes open to allow air to the roots and also help drainage.

Your lawn will look a mess for a week or three but once it has rained and the grass has grown a bit you can cut it and that will make it look a whole lot neater.   

andy625uk

Fairygirl

They're becoming quite wideread now. Mainly in the damper areas. They're not related to the bald patches, they are due to the hot weather. Not surely about hedgehogs, but we do have mice and squirrels.

andy625uk

Obelixx

I could believe its due to the damp. The ground is very heavy clay, and I haven't been as good with the scarifying and aerating as I normally am. Its not a very big lawn, and the areas with the black are in the damper parts. I do have a scarrifyer, so I'll give it a good stub and fork it over, and do my best to keep it drained over the winter.

Thanks for the replys.

Obelixx

Regular scarifying and aerating will do wonders for the health of the grass and its roots, especially before the worst of the winter wet arrives.   Give it another go next spring and then a feed once it recovers an it should look much better.  Repeat every autumn and spring if you can.

treehugger80

one question, do you have a dog? as dog wee on heavy clay soil can cause bald patches like that.

or alternatively did you have a large number of crane flies appear in September? as their young live in lawns and eat grass roots

andy625uk

No we don't have a dog. We have a cat, but he normally just fertilizes the borders. The bare patches are only because of the drought as I didn't use the hose this year.

Fairygirl

It's the dark bits Andy's concerned about, treehugger 

I think if you're finding it's the damp areas which are worst, then scarifying and/or giving the ground a good stab with a fork might help, as Obelixx suggests. 

Dovefromabove

Can't see it clearly, but I'm wondering if it could be a form of Dog Lichen or similar

https://www.rhs.org.uk/advice/profile?PID=414

Fairygirl

I wondered about that too Dove, but Andy's description didn't mention any kind of growth. It was more like a little bit of compost dropped on the grass. 

I used to get dog lichen in the garden round the corner- very compacted, poor grass [mature trees etc close by] and lots of rain. Ideal for them