Author/Authors :
Anita Singh، نويسنده , , Madhoolika Agrawal، نويسنده ,
Abstract :
The present study deals with the assessment of changes in physical and biochemical characteristics of soil and
metal partitioning in Beta vulgaris L. grown in farmer’s fields irrigated with waste water in Dinapur and Lohta areas of
Varanasi, India, during December to February, 2007 -2008 and 2008 -2009. Nutrient concentrations, organic carbon,
microbial biomass, C, N, and P, enzymatic activities and heavy metal concentrations in soil and plant parts were estimated
at waste water (DW1, DW2 and LW) and clean water-irrigated sites (DC and LC). Sites receiving waste water irrigation
showed an increase in organic C by 36 and 64 % and in available phosphorus by 15 and, 21 % at DW1 and DW2 sites
compared to DC and 88 and 29 % at LW compared to LC during the first year. Dehydrogenase and urease activities
increased two to threefold at waste water-irrigated sites compared to the respective clean water-irrigated ones during both
the years of study. Microbial biomass (C, N, and P) and concentrations of exchangeable cations (Na?, K?, and Ca?2) also
showed increments varying from two to threefold at waste water-irrigated sites. During both the years, total heavy metal
concentration in soil was the highest for Mn followed by Zn, Pb, Ni, Cu, Cr, and Cd at Dinapur, whereas at Lohta the trend
was Mn, Zn, Cr, Pb, Cu, and Cd. The accumulation of heavy metals in the plants was several-fold higher in roots and
shoots at waste water-irrigated sites, and Cd, Pb, and Ni were above the safe limits in edible tissues. Lower metal
concentrations were recorded at DW1 site compared to DW2 and LW sites. The study suggests that waste water irrigation
led to beneficial changes in physico-chemical and biological properties of the soil, but increased the soil contamination of
heavy metals. However, the intermittent use of clean water in such areas may not only reduce the metal contamination in
the plants but will also maintain soil fertility.
