Long-Term Effect of Flocculated Sewage Sludge on Growth of Poplar under Drought Conditions.

<p>Poplar is popular for protective forest plantations and raw material for renewable energy and other industries. A long-term experiment with the <em>Robusta</em> clone to determine the effect of untreated and flocculant-treated sewage sludge was established on phyto-remediated loess-like loam at the DSAEU Land Reclamation Research Station in the Dnipropetrovsk region with applications of 20, 40 and 60 t/ha of both untreated and flocculated sludge. In the sixth year, in comparison to the control, the flocculated sewage sludge increased the average tree height and diameter of the three variants by 11 and 19.5%, respectively; somewhat less in the case of untreated sludge. The specific leaf area in the variants receiving flocculated sewage sludge was lower than in those receiving untreated sludge by 13-23%. Under drought conditions, the combination of greater organic matter and nitrogen and lower content of heavy metals in the flocculated sewage sludge was more favourable for the growth of poplar during six years of its cultivation.</p>