Effect of some soil properties on growth of three-year black poplar (Populus nigra L.) trees in poplar plantations in south of Tehran

The effects of some soil properties on growth of three-year poplars (Populus nigra L.) were investigated in two poplar stands in south of Tehran. For this purpose, at the end of growth period, in each poplar stand, three sample plots (3×4 m) were chosen using technique of systematic random sampling. Diameter at breast height and height parameters of trees were measured and then basal area and volume computed. In order to study soil properties (texture, organic matter, pH, EC and NPK), in each plot, three soil samples were taken in depths of 15-30 and 30-60 cm. Results demonstrated that some soil properties (sand, silt and clay percent, K content and EC) of two poplar stands had significant differences, as a consequence growth parameters of two poplar stands also showed significant differences. So that, in stand 1 volume of three-year poplar tree was 3 times volume in stand 2. In general, loamy-clay soil with higher absorbable K (415/16 mg/kg) and lower EC (1/36 ds/m) (stand 1) provided better growth conditions for poplar trees compared with loamy-silty soil with medium absorbable K (219/43 mg/kg) and higher EC (4/43 ds/m) (stand 2). Also, positive correlation between growth parameters of poplar trees with sand and clay percent and K content and negative correlation with silt percent and EC were observed. The results of current study demonstrated that attention to soil properties before poplar plantation is necessary to achieve maximum wood production.