Hi all – for me, this conversation is becoming extremely interesting and useful.
Charles said that ‘undecomposed manure/slurry/dung/fresh poo does leach nitrogen’ and I think it is true to say that all of those things are uncompromisingly ‘green’ in their contribution to any kind of composting process. But a thick mulch of, for example, comfrey leaves would be specifically intended to ‘leach’ its chemical constituents into the soil in the same way as a re-incorporated green manure. Obviously, a thick mulch will also suppress the growth of unwanted plants (weeds) and also provide protection against physical soil erosion. Maybe we need to make a distinction between leaching nutrients ‘into’ the soil and leaching nutrients ‘out of’ the soil!
Charles also says that ‘green manures add organic matter, which is often overlooked in discussions which centre on nutrients’ and, for me, this relates directly to the idea of making comfrey tea etc. I don’t yet understand the purpose of soaking comfrey leaves in water and then pouring the water into the soil – why not just place the leaves directly onto the soil?
Finally (for now!), I also don’t much like using plastic sheeting and, last October, I covered a 4.5 metre by 2 metre bed with thick cardboard and lashed it down with netting. Right now, the appearance of the cardboard has hardly changed but, if I touch it, it has decomposed into little more than a thin smear which easily rubs into the underlying soil. My partner’s intention is to use this bed for growing potatoes in the conventional manner and I am tempted to remove the netting and spread a layer of chopped up green leaves and grass cuttings etc in order to complete the decomposition of the cardboard.
Tomorrow’s job is to get my newly-bodged 6’x3′ cold frame out of my son’s back yard and over to the allotment – most of the family will be involved and I daresay there will be a well-earned pint or two afterwards.
Ken