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Community garden composting + bokashi vs. late blight spores question

Dave de Basque
Posts: 95
Location: Basque Country, Spain-43N lat-Köppen Cfb-Zone8b-1035mm/41" rain: 118mm/5" Dec., 48mm/2" July
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We have a community garden with about 60 small plots where people of all levels of experience with gardening, but a huge majority of newbies, each go about their own business and do what they please.

We have some composting areas where people are supposed to leave their garden waste, and a few of times a year, we organize a compost-pile-making party. So far our compost making has been disastrous and we'd love some help.

Here are our needs:

1) Simple soil enrichment. We've got heavy clay soil that seems to be fairly fertile. Over time we need to lighten it and incorporate more organic matter, and we need to put something back for the nutrients we take out every season.

2) Phosphorous deficiency. We've done a soil test on soil from several plots, and our soil seems to do quite well except that it is very low in phosphorous. Perhaps not surprisingly, we have a huge problem with late blight on our tomatoes -- every plant gets it every October, more or less.

3) Recycling our garden waste. This includes all the old plants from the squash family affected by powdery mildew, all the old tomato plants affected with late blight, and other diseased plants here and there as well as all the normal, healthy garden waste. There is NO chance of 100% compliance in terms of any rule like "make sure not to throw any diseased plants onto the compostables pile," so don't even go there. We need a compost system that will deal with at least some, if not a lot of, diseased plants, and yield pretty much disease- and spore-free compost.

OK, so here's what we've been doing.

1) Fresh sheep manure. About every 6 months, we get about 15 cubic meters of the last six months of sheep poo from a local farm that is part free-range and part small-scale not-too-awful CAFO, where the poo and urine just falls through a grating into a pit, not mixed up with straw. We are under a bit of pressure to continue taking delivery of same and using it somehow. We have been told we ought to be mixing it with 1/3 its (tremendous) weight in straw. And we are just as excited as you might imagine, lacking a tractor, at the prospect of mixing 15 m3 of fresh sheep dung with straw by hand, with shovels. So so far we are leaving the pile to rot under a sheet of plastic (must not irritate the noses of city folk in swank new apartments nearby) until it becomes a useful amendment for our gardens. Are we just deluding ourselves? Will we ever have a usable soil amendment?

2) Chicken manure etc. There is an organic chicken farmer in the next town who has a small amount (maybe 1-2 m3 every 6 months) of excess manure, which we understand is normally high in phospohrous. We take all that he can give us, and it's usually fairly well rotted by the time we get it. This smaller, and much drier, amount we don't mind mixing with straw, which we've done and covered it with breathable fleece. We thought it didn't need anything else and was ready to go. But the local composting expert tells us that it's not composting and we should mix it with pile 3 below. In other news, there seems to be no way to lay your hands on soft or hard phosphorous as an agricultural soil amendement where we are, for reasons that are beyond me. Said composting and soil expert says, don't worry about those silly "deficiencies" on your soil test, just get some ground up volcanic rock and that will solve everything. Whatchy'all think o' that?

3) Garden waste. Our first pile was made under the watchful eye of someone who knows his stuff. We alternated layers of hay and straw, garden waste, added a bit of manure for good measure, and watered fairly well. After maybe 4 sets of alternating layers, we covered with straw and stomped it down. It was at least 1m on each dimension. However, it did not heat up and it looked basically the same after 2-3 months though the volume decreased by 2/3 or 3/4. So we turned it and combined with new garden waste, more straw and hay, and a LOT of manure, and really drenched it with water. (I saw it on a YouTube video, you know -- if your compost heap hasn't heated up, it's because it's too dry, so add more water. Oops!) Anyway, I'm sure we waterlogged it. But in any case, it still has not had any "hot compost" action and all those old diseased tomato stems are still intact. We need to learn to do this better. Where is a good "Hot compost 101" tutorial? And what do we do with our present mound? There's a bunch more garden waste to mix with it now if we want.


Another system we want to experiment with is bokashi + vermicompost. So we'd like to take people's household organic waste and bokashi-ferment it, and then throw it to the worms. Hoping to get out very high-quality usable compost relatively quickly. So this is not the destination for garden waste, too unwieldy for the large volume I think, but it did bring up the question: Would bokashi fermentation kill off late tomato blight spores? We know that the worms, miraculous though their work may be, will not do that. But I was hoping that maybe the anaerobic bokashi "pickling" might. Anyone know the scientific scoop on that one?

Thanks for all good advice from you experienced compost hands.
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