Abstract:

The humic substances characteristics of the mixed and pure plantation of poplar and black locust in sandy soil were studied,the results were as follows:Compared with soil without forest,after the mixed and pure plantation of poplar and black locust being planted in sandy soil,soil organic C and humic C increased,the light density value of humic acid,HA/FA ratio,E 4,E C,and RF values raised,Δlog K decreased,soil loose (Ⅰ) and tight (Ⅲ) combined form humus contents and the ratio of Ⅰ/Ⅲ went up,the ratio of organic C content in soil stable combined form humus (Ⅱ) to that in soil declined,indicating that the polymeric degree of soil humic substances raised,the atomic groups of aromatic nucleus increased,the aromaticity,complex degree of aromatized molecules and humification degree all went up,the quality of humic substances became better,soil maturity raised,soil nutrient-providing and nutrient-holding capacities increased and the soil fertility promoted after the mixed and pure plantation of poplar and black locust being planted in sandy soil.The increase in sandy soil fertility degrees followed the order:mixed plantation>black locust plantation>poplar plantation.

Key words: Sandy soil, Poplar, Black locust, Mixed plantation, Humic substances