Science Forums 2

[Rev]

Well ill offer an alternative model for this biochar addition

im on about 30-40cm of loam to clay loam above clay on flat country
its inland in the subtropical area of northern NSW
subtropical in the summer, but quite cold in the winter. last winter the minimum was -6C but its usually 12-20 frosts a year at about -4C

the soil is already good but i want to make it better at holding the nutrients i put in

ive been making char is a few ways. making the char is as much about removing garden waste and dealing with problems involved like pathogens and weed seeds as its about the char

waste materials are food scraps, seasonal prunings, leaf fall, weeds, lawn clippings, spent mulch, card and newspaper, animal bones, and old bamboo stakes cut down at the local patch
waste is partitioned 3 ways; food grade waste goes to the chickens and ducks, low carbon : nitrogen ration waste goes to compost and high C:N waste now goes to char
the difference being around a C:N level of 25:1

char has been made 3 ways
1. managed open fire method. Some things char well and fast when openly burnt if the fire is managed. Grass, lawn clippings, straw.
a fire is lit and materials thrown on a little at a time, the next addition smothers the previous stalling it in a char phase before it burns to ash , or else i wet it down or tamp it out. it can be fairly quick and productive

2. In a steel bin. a convereted 60L oil drum with holes in the base and a lid if needed. paper products, leaves, bamboo wastes, sticks especially thorny ones liek rose prunings and infected plant materials
same strategy as the open method, keep filling it. soon it gets very hot and material chars without completely burning and flames shoot out the top some distance.
good to get rid of paper especially and the whole thing is quenched with the hose when im done

3 earth mounds. this is good for the big stuff. light a fire get it roaring then load on more wood and what youve got - then cover the hole thing with dry woodchips then with earth so just a tiny amount of smoke seeps out. if smoke increae mpatch up with more earth. a slow but easy process
when finished break apart and the yield scan be quite good.

my favourite method is to take the char from any method and run through a garden sieve. large chunks go around the fruit trees , fines fall through and go to a gedye style compost bin.
in this i build up alteranating layers of char , household and garden scraps of low C:N ratio and some additives - like rock phosphate, Bone meal gyspum or dolomite to add the crucial P, Ca and Mg that are so characteristic of the black earths. Once full i let it sit till i need it t o dig into a new bed

if using plain char i like to mix it 50:50 with compost (not a rich one so i add a complete NPK fertiliser and some powdered Kelp)

The results are very promising
fungi and worms visibly love the half burnt materials
and growth rates have been sustained

i would like to see char levels hit 35% in the top 20cm in time
but id also like to see compost additions equal annual char additions
and it must remain finely textured - for vegetables
and i continue to fill up that space with the ions of Mg, P, Ca, ammonium and sulphur

all waste (large) char goes around fruit trees.

ive used 50:50 char:compost as a potting soil for vegetable seedlings with excellent results - and cheap!

i dont apply char to acid lovers.