Long-term impact of municipal sewage irrigation on treated soil and blacklocust trees in a semi-arid suburban area of Iran
Masoud Tabari , Azadeh Salehi
DOI:
Received November 04, 2008,Revised April 08, 2009, Accepted , Available online
Volume 21,2009,Pages 1438-1445
- Summary
- References
- Related Articles
The effects of municipal sewage irrigation on the soil and black locust (Robinia pseudoacacia L.) tree were studied. For this purpose,
two artificial black locust stands under irrigation of municipal sewage and well water were selected in south of Tehran, Iran. Data were
collected using technique of systematic random sampling with 4 replicates in each stand. It was found that the growth of black locust
tree, as indicated by diameter at breast height, total height, crown length, average crown diameter, basal area and volume, in sewage
irrigation stand was much higher than that of well water irrigation stand (P < 0.01). Plant analysis indicated that concentrations of leaf
nutrients (N, P, K, Ca, Mg, Na, Fe, Mn, Cu and Zn) were greater in sewage-irrigated trees, without toxicity to the minerals of tree leaf,
than those of well waterirrigated trees, and positively correlated with their respective value in soil. Ni, Cr and Pb were not detected in
leaf samples. Application of sewage resulted in a 1.5-fold increase in the concentrations of soil nutrients, Ni, Cr and Pb. Among these
minerals only Pb and Ni in some soil samples exceeded the toxicity limit. The increase in pH, electrical conductivity (EC) and organic
carbon of soil was also observed in sewage irrigation. Results confirm that besides the use as irrigation water, municipal sewages are
also a potential source of plant nutrients. However, significant accumulation of heavy metals such as Pb and Ni in soil needs to be
monitored.
