Getting the Carbon:Nitrogen Ratio right when Growing feild mushrooms / Agaricus bisporus

Hi,

We are trying to grow these on a small scale (like 50 Gallons / 200L drum-full of compost at a time).

I have read a lot of recipes and literature on making the compost and pretty much understand it to be:

- A source of rough carbon to make a loose compost (straw and/or corn cobs usually)

- Enough nitrogen to bring it to the right ratio (various sources of hay, manure, high protein/nitrogen meals and/or chemical nitrogen)


My problem is that our two main sources of organic nitrogen are ones that can have a lot of variance - pastured cow manure and grass clippings/fresh hay.

http://cdn.intechopen.com/pdfs-wm/19993.pdf

This reading puts the carbon:nitrogen ratio to be at a minimum 16:1 maximum 22:1 and ideal 19:1. I doubt I will go higher than 16:1, but if I go lower than 22:1 on some batches will it be a huge issue, or will the compost still just produce mushrooms till the nitrogen is spent? As long as I can get the whole heap hot - but still friable - in an insulated drum, then will I be in range? Is there a way to guestimate you are in this region somehow?

We are making the compost from farm materials and bought-in organic wheat straw (hope to produce our own straw and corn cob in the future), and then turning it into compost for our market garden afterwards, so it is far from a wasted process to have some batches under-producing compared to others. (we are in a climate that averages 3C to 13C temperatures in winter, and 12 c to 22c temperatures in summer, so an insulated shed some thermal mass and compost heat in winter is pretty much enough keep the mushrooms in growing temperatures range without paying electricity for heating or cooling).
As long as we get some production we would rather have some variance in production than spend a lot of time and money testing each batch.

Annie

These mushrooms normally grow in the ground on flat surfaces, which have extra nitrogen. That's why they are there. I wouldn't try to grow them in a container. I think that human or animal urea would be a safer source of nitrogen than synthetic chemicals. Bisporus/grocery store mushrooms are often said to be incredibly difficult on a home scale. Be very careful on mushroom ID for agaricus. Many won't eat them categorically becuase there are so many in that genus that will make you sick.
John S
PDX OR

Hi,

Maybe my initial question was not clear enough. We are actually wanting to grow these on a small commercial scale. We will be heat composting and then seeding with purchased spore, so identification won't be a issue.

We are growing organically and were not considering chemical nitrogen. Hence the question - the two organic sources of nitrogen we have available are pastured cow manure and grass/hay - which can vary a lot in their nitrogen content. We have unlimited racehorse manure and chicken manure for the taking near-by that is not organic, but have heard too often that the hormones and other chemicals given them do not break down in heat composting.

We used to pick mushrooms on my uncle's farm quite often when he had not fertilised for a couple of years, but have not seen a field mushroom on our 8 acres in the five years we have been here, although the previous owners also pastured cattle and goats, and did not use chemical fertilisers either. He had very hilly clay, and the mushroom usually grew on the hill valleys, and we are on a flat very sandy soil, so may just not have the right structure at all.

Annie

Thanks for clarifying.
You talked about using chemical nitrogen in the original post.

Sandy soil can be a problem, but if you add lots of slowly rotting organic material, that should help a lot. It won't drain so fast then Straw, stems, wood chips, anything that will turn slowly should provide excellent employment for your fungal species. High nitrogen is a great idea too.
John S
PDX OR

could compost a little blood/ bone meal in there to add nitrogen and potassium. that will get your pile to heat up. use sparingly though. they like completely finished compost so i wouldn't inoculate till the pile starts to cool. I've tried growing A. subrufescenses, the almond portabelo and counldnt get the mycelium to establish itself. the compost i used was finished but i mixed in shredded straw/leaf littler and it never took. agariucus is a fussy shroom from what I've read. you ever think of trying oysters on hardwood sawdust or shredded straw? they are quick to colinize and are delicious! elms are my favorite!