Abstract:

The effects of humic acid application on biomass of I-107 Populus euramericana, soil nutrients and enzyme activity were studied under regular- and higher-fertilized level with a potting experiment. The result showed that: The application of humic acid with inorganic fertilizers significantly increased the root, stem and leaf biomass of I-107 P. euramericana, and among them the increase of root biomass was the most by 58.60%. Addition of humic acid also increased the nitrogen, phosphorus and potassium nutrient contents in the poplar by an average of 5.35%, 25.52%, and 25.06%, respectively, therefore, the contents of soil available phosphorus and available potassium were lowered. Compared with inorganic fertilizer, the addition of humic acid also decreased the content of nitrate nitrogen, increased the content of ammonium nitrogen, total C, humic acid and fulvic acid, as well as the ratio of humic acid to fulvic acid. Under regular and higher-fertilized, application of humic acid increased urease activity by 24.71% and 5.83%, respectively, enhanced polyphenol oxidase activity by 21.05% and 46.34%, respectively, but had little effect on catalase activity. To sum up, application of humid acid with inorganic fertilizers had significant effects on nutrient absorption of the poplar and soil fertility.

Key words: humic acid, Populus×, euramericana cv. &lsquo, 74/76&rsquo, soil, enzyme, nutrition content