[mathuranatha]

Hey ,I've dug a pit [about 2 cubic meters] and have accumulated a big mound of charcoal [3or4 cubic meters] and am wondering how best to crush it or if crushing is necessary . I made some garden beds, some without biochar and some with[30%]about 2 months ago , not much difference in growth rates though and that was roughly crushed by hand.

[freeztar]

The more you grind it, the more surface area you will have for micro-ecosystems to take advantage of.
Try smashing it with a brick and then doing the "TP Twist" dance to get a finer grit.

[maikeru]

Originally Posted by mathuranatha

Hey ,I've dug a pit [about 2 cubic meters] and have accumulated a big mound of charcoal [3or4 cubic meters] and am wondering how best to crush it or if crushing is necessary . I made some garden beds, some without biochar and some with[30%]about 2 months ago , not much difference in growth rates though and that was roughly crushed by hand.

Did you saturate or "fertilize" the charcoal or biochar soil with some rich nitrogen sources like chemical fertilizer or manure? If not, do it asap, as low amounts of nitrogen will retard the development of the microbial community and plants. I believe that charcoal's ability to bind nutrients also sucks up initially available N, but once the microbial ecosystem gets going, N release and storage will be very good. When I first used biochar, my plants didn't grow as fast and I thought I must've made a mistake. Then later, I discovered that the char needs a heavy dose of N, through some means, to help establish the microbes and plants.

[Philip Small]

Originally Posted by mathuranatha

Hey ,I've dug a pit [about 2 cubic meters] and have accumulated a big mound of charcoal [3or4 cubic meters] and am wondering how best to crush it or if crushing is necessary.

Short answer is that crushing is not necessary, burial is not necessary. Bury if you have small amounts of charcoal per unit area (1 cubic yard/acre). Banding it down the seed row with a small amount of starter fertilizer, makes good sense. Charcoal, even in small amounts, is a good complement with biofertilizers, like activated compost teas.

At the other end of the scale (100 cubic yards/acre), screen it to get the crushed needed, and fling the rest out as chunks on the surface. Work it in (or not) as the opportunity presents itself. In landscaping, horse pasture, or woodlands (as some of us have in our back yard), I wouldn't worry about working it in. In a garden situation it could go on top of a layer of compost, topped off with leaf or grass mulch.

Originally Posted by mathuranatha

I made some garden beds, some without biochar and some with[30%]about 2 months ago , not much difference in growth rates though and that was roughly crushed by hand.

Prep the charcoal with a light, uneven spray of a soluble N fertilizer. It's a salt, so excess rough on the microbes. - I use MiracleGro because it is handy, but ammonium sulfate would be less $$. Another alternative is to finish the charcoal in compost, apply it as a compost mix. If the compost mix is high in charcoal, a little soluble N fertilizer will help it get through the high C:N hump.