cause stalled growth?
Adding charcoal to soil can cause growth to stall where soil nitrogen levels are low. That is probably not the case in most garden situations which have the advantage of compost, manure and kitchen scraps. The combination of returning bio-chars with high C/N ratios and abiotic buffering of mineral N may in some situations lead to low N availability to crops (Lehmann and Rondon 2005). In experiments in northern Sweden, however, increased nitrification and decreased ammonification was found after the addition of activated C to a pine forest (Berglund et al. 2004). It appears that the effects of bio-char on N dynamics in soils is not entirely understood. In a greenhouse study in Colombia, leguminous plants were able to compensate for low N availability with increased biological N2 fixation which is actually stimulated by bio-char additions (Rondon et al. 2004). Non-legumes, however, may require additional N fertilization to compensate for the immobilization. This is an undesirable effect
