Distribution patterns of PG fraction of P-type humic acid and iron in a dark brown forest soil

acide acide humique acide organique acids agentes nocivos cambisol cambisoles cambisols chemistry chimie chimie du sol composition contaminantes contaminantes industriales cultural soil types ecological soil types elements environment environnement facteur nuisible fer forest soils genetic soil types heavy metals hierro humus industrial pollutants injurious factors iron medio ambiente metal metales metales pesados metals organic acids organic compounds organic matter content polluant polluant industriel pollutants site factors soil chemistry soil types suelo forestal transition elements type de sol type de sol de culture