So, if you had some land that you planted to green manure- mostly mustard, phacelia and buckwheat (ie: non-hardy things), but then life intervened and you never got round to digging it in. And now its all flowered and seeded and dried off over the summer... what would you then do? The frosts will be here in 2 or 3 weeks, do I have time to dig it in and start some new hard green manure off? I have alfalfa, lupin, ryegrass, etc, that I can seed- but I'm not sure there's enough time? Is it better to leave the dried stalks of the current green manure standing and start again next year? I don't mind the seeds being there as I'll sheet mulch it next year.
The land is a north facing slope- and rather prone to erosion over winter. I'm in the UK, so winters don't get very cold (-5C at the coldest), but we get a lot of rain.
Any ideas? What would be best for the land as regards now losing soil or fertility?
If you sheet mulch anyway, why not just let it stand to protect the soil from erosion?
After the sheet mulching it will be compost anyway. Maybe think about sheet mulching it now while it is still warm enough to use the fall breakdown period to have the roots and stalks as ready compost to plant in spring.
With your statement about erosion the last thing I would do is dig it in or do any other form of tilling.
I struggle to get enough organic materials for proper sheet mulching Whilst I have plenty of cardboard and a few bags of wood chips, I'm struggling to get anything else! By spring I hope to have accumulated some more! I could cardboard it now and spend all winter chucking more stuff on (soon there should be a cube or so of compost ready, and lots of leaves.
I want to use the area for growing annual crops, and I don't want to dig it (due to erosion, and all the green manure seeds that will now be buried there!)
I've got some big sheets of black plastic I could use... but is it best to put it down now or wait until after winter (and the windy part of the year!)
I would imagine that by now the phacelia, mustard and buckwheat are going over. You could either pull them up or just cut them off with shears, leaving the roots to decompose in situ and then sow field beans, forage pea or forage rye (all of which can be sown in October in the UK (check the website for Sow Seeds http://www.sowseeds.co.uk/product-category/sow-by-month/october/). You can sow the field beans and forage peas in November as well. It's too late for the alfalfa and lupins though.
If you don't sow anything then I would leave the plants that are there in place and deal with it all in the spring. My reasoning is that it's best to have something growing rather than nothing as this keeps the soil food web recharged and going all winter. Failing that it's better to have something dying back than nothing as this at least feeds the decomposer organisms. The least favourable option is to have bare soil over the winter. But if you don't have time etc don't worry about it, as you have said "life intervenes" and disrupts what we would like to do, but there is always next year to make a fresh start.
Diego Footer on Permaculture Based Homesteads - from the Eat Your Dirt Summit