I am just finishing trench nine and beginning trench ten. The soil is becoming much more heavy with a lot of clay. I have moved the stones in the path I made last year to the left hand side of the allotment to make a good path there. The stones will help to keep the allotment drained particularly as there is a lot of clay. I will cap them off with two foot square slabs. I dug out the top soil from where the path was going, sieved it and put it onto the growing area of the allotment. No point in covering good top soil with a path. The stones filled the hole admirably. I will have to use some of the slabs as curbing because the soil has been raised so much. I am adding quite a lot of shredded brushwood to the subsoil of the triple dig trenches. The shreddings pile is steaming and full of fungi mycelium. Shows you could use this to make a hotbed.
The green manure seems to be growing well because the temperatures are staying around 10 degrees even during the night.
As part of the triple sieve digging, I am mixing in rock dust on the areas that I am going to use for the peas, roots and leafy veg. Just to see if this makes any difference.
As the soil was becoming very heavy and clay like, I decided to add some horticultural grit just to break up the soil and make it more workable. However, I thought that if I was going to add grit, I might as well add rock dust instead because that will add some nutrients as well.
Most natural nutrients come from the weathering and erosion of bedrock. (You get some nitrogen fixed by bacterial and some nutrients like sulphur and nitrogen from rain) . So, I have added rock dust as I sieved the top soil.
Whether the nutrients in the rock dust are readily available to plant roots or whether they need to be further broken down is debateable but regardless I get the benefits of better drainage and a soil that is easier to work.
I would suggest that mychorrhizal fungi might be able to access this nutrient store breaking down the dust using powerful enzymes and acids secreted from their hyphae. If this is possible then the plants they are associated with might benefit.
Now that I have been mulling this over, I am wondering if mixing crushed inoculated charcoal will add to its efficacy. The charcoal has been marinating in comfrey liquid for over six months now so should be fully charged with nutrients.
Maybe I will add this to the leafy veg soil. I will be making biochar from shredded bark chippings in the spring. That will be interesting - for me.