How to Apply Spent Mushroom Compost

[missanja]

I really appreciate all the great information here. Thanks guys (where are all the women?)!

I have a question regarding the application on spent mushroom compost. I am working in a suburban plot in Sydney. I suspect contamination. The back end was filled with garbage for leveling. I found oil filters and batteries. Some of the soil smelt like oil. All sorts of plastic too, much of it PVC. Also there are some structures in the area from CCA treated wood. Can't afford to get the soil tested so I have decided to assume it is contaminated and just got forward with bioremediation.

I snagged some oyster mushroom compost for free! I have read that osyter mushies are good at mineralizing petroleum based products as well as some organopollutants. Not sure on the CCA though.

So my questions:

- should I mix it into the soil or just put a layer on top of it? I have one study where better results were obtained from mixing, but this was in a column in a lab!

- the oyster mushrooms were grown in straw but is is partly decomposed, should I cover with some sort of mulch as feed for the mycelium? I can get mulch high in N, such as alfalfa or lucerne hay.

- should I cover it all with a tarp? I have read that temps above 30C are best. It is summer here in Oz but not always above 30, a tarp might help bring the temp up.

- what about moisture, should I water the compost once it is down? A tarp would also help with maintaining the moisture content.

I'd appreciate any feedback. Practical information is hard to come by and most studies are ex situ not in situ.

Cheers!
Anja

[jstorvick]

Hi Anja, thanks for stopping by! We definitely DO want to even up the gender mix as much as possible, not just boys' fun and all of that

First, I would apply your mushroom compost on top of the soil rather than mixing it in. Since you suspect contamination in your soil, you definitely want as many beneficial microorganisms working on the nasty stuff as possible. Mixing up the soil (even with good stuff like compost) tends to wreak havoc on the soil food web. You'll get great results simply by adding organic material to the surface, where it will naturally work its way doin into the soil horizons with the help of our microscopic allies.

Second, as far as medium for mycelium to latch onto - cardboard and coffee grounds (you can get TONS from your local coffee shop) are two really good materials, esp. for oyster mushrooms. I'd suggest laying down some cardboard, wetting it thoroughly, covering with used coffee grounds, and then layering your mushroom compost on top, making sure to keep everything thoroughly moist. Wood chip mulch should be pretty useful, too, though I'm not sure about alfalfa straw in particular for oyster mushrooms. You might want to check out some of the edible fungi sites online for more info.

Depending on the shade conditions, you might want to put a tarp over it if you're looking to grow mushrooms. A bit of darkness certainly helps.

As far as moisture goes - you want to keep it moist but not waterlogged. Keeping some airflow going (ie. not smothered by a tarp, but leaving some space for air to move) will prevent bacteria from competing with the fungi.

Hope this helps out!

Cheers,

Jon

[missanja]

Hi Jon,

Thanks so much for your response. I read it after I had actually done all the work but you have lots of great advice. Coffee grounds are a great idea.

I ended up using the alfalfa hay. I put it on top but it probably would have been better underneath. It has been sitting for about 10 days now. I covered it all with the black plastic bags the compost came in. I just cut them open. Great thing is they already had holes for the mushrooms to grow out of so it should all have pretty good ventilation. It has been bloody hot here for some of the days, up to 40C. So hopefully I should be getting tome good growth. I will be taking the plastic off in a few days to take a look and if it is not growing well I will add the coffee grounds and cardboard. Should be pretty easy to slip underneath.

Unfortunately, I had to dig in the soil. I want to get as much rubbish out of it as possible. So I dug a pitch fork level down across the whole area. I ended up taking out seven oil filters.

Thanks again for the fab advice.

Cheers,
Anja