Fig. 1.From: Molecular characteristics of humic substances from different origins and their effects on growth and metabolism of Pinus laricio callus13C-CPMAS–NMR spectra of humic acids: HA-C leonardite; HA-D oak forest soil; HA-E industrial compost after 150 days of maturation; HA-F Hungarian lignite treated with gluconic acid before extraction; HA-G industrial compost after 30 days of maturationBack to article page