Effects of humic acids from compost-stabilised green waste or leonardite on soil snrinkage and microaggregation

Humic acids extracted from composted vegetable residues (green compost) or mined lignite (leonardite) have been tested for their influence on either soil cracking or microaggregation characteristics. This preliminary study has pointed out that humates from green compost, within the range of 1000 to 8000 mg kg-1 of soil, induce smallsize clod formation in a dose-independent manner and preserve stability of microaggregates. On the other hand, humic acids from leonardite did not improve soil shrinkage and water-stable microaggregates, but rather they determined deterioration of such physical characteristics of the soil tested